Vai ai contenuti. | Spostati sulla navigazione | Spostati sulla ricerca | Vai al menu | Contatti | Accessibilità

| Crea un account

BOTTEGAL, MARIANGELA (2009) An apparently useless conserved gene in Rhizobium sullae. [Tesi di dottorato]

Full text disponibile come:

[img]
Anteprima
Documento PDF
7Mb

Abstract (inglese)

Rhizobium sullae, a nitrogen fixing symbiotic bacterium, induces nodules formation on Hedysarum coronarium L.
Although the ability to denitrify may enhance bacterial survival and growth capability in anaerobic soils, denitrification among rhizobia is rare, and only B. japonicum and A. caulinodans have been shown to be true denitrifiers, reducing nitrate (NO3-) simultaneously to both NH4+(assimilation) and N2 (denitrification), when cultured microaerobically with nitrate as the only nitrogen source. R sullae strain HCNT1 has been shown to have a copper-containing nitrite reductase (Nir), producing nitric oxide (NO), encoded by a nirK gene, but not a complementary nitric oxide reductase and the other enzymes required for a complete denitrification pathway.
Expression of nirK is atypical in that it does not require the presence of a nitrogen oxide, but only a decrease in oxygen concentration. Reduction of nitrite (NO2-) by strain HCNT1 results in the inhibition of growth due to the accumulation of NO to toxic levels, suggesting that R. sullae does not contain any Nor (nitric-oxide reductase). Nodulation, plant growth and rates of N2 fixation are similar between wild-type and nirK-deficient strains.
The physiological role of the truncated denitrification chain found in R. sullae is not obvious. It is possible that Nir activity allows the bacteria to convert into a VBNC form, which would survive for long periods under stress conditions without loss of the ability to recover the vegetative state.
Recently strain HCNT1 was found to be able to grow in the presence of high concentration of selenite (50 mM); moreover, during the growth, selenite was reduced to less toxic elemental red selenium, as indicated by the appearance of red colour in the culture. A mutant strain of HCNT1, HCAT2, lacking nitrite reductase, showed no evidence of selenite reduction, grew poorly in the presence of 5 mM of selenite and was unable to grow in the presence of higher concentrations (25 or 50 mM). Other strains, like A4, isolated from the same site where HCNT1 was originally collected, showed a similar behaviour of HCNT1, while its nirK- mutant, a became similar to HCAT2. Once again, the loss of nirK gene seemed to make strains much more sensitive to selenite.
Furthermore, a naturally occurring nitrite reductase deficient R. sullae, strain CC1335, isolated from a quite different site, was found unable to grow in the presence of selenite. Mobilization of nirK gene of HCNT1 into CC1335 increased its resistance to this oxyanions.
These data have suggested that nitrite reductase of R. sullae could provide resistance to selenite indicating a possible explanation for the radically truncated denitrification chain, found uniquely in this bacterium.
On the basis that Nir was able to reduce different oxyanions in addition to nitrite, such as selenite, it has been proposed a multifunction mechanism for nitrite reductase. In order to support this hypothesis, any possible correlation between nitrite and selenite reduction was evaluated. It was demonstrated that selenite reduction occurs either in aerobic or in anaerobic condition and that it is a constitutive enzymatic activity, unlike nitrite reduction activity that requires the induction after a period of incubation under limiting oxygen conditions. Moreover, the addition of nitrite in the culture containing selenite did not prevent the reduction of this oxyanion to elemental selenium form. On the other hand, the presence of selenite in cultures containing nitrite prevented the production of nitric oxide, either if it was added before or at the end of the induction phase.
The enzyme responsible of selenite reduction has shown to contain copper, since it responds exactly like the known Cu-nitrite reductase to the addition of a specific chelator (DDC) , that completely inhibited selenite reduction and the consequent appearance of the red colour.
Therefore, protein purification became critical in order to better understand its properties. This activity requires a suitable strategy and an appropriate biological system. E. coli, generally used for this purposes, showed to possess different metabolic pathways leading to reduce selenite to elemental selenium. In order to unambiguously proceed to the production and purification of Nir, the construction of a recombinant protein polyhistidine-tagged (6xHis) for the expression in E. coli and the subsequent affinity purification, was carried out. This produced a unexpected delay for the last experiments. However, Nir protein has been purified and some tests for nitrite and selenite reduction activities were performed with the aim to clarify if the two enzymes are the same protein working in a different way, depending upon the substrate and the general conditions adopted. The preliminary approach on a first fraction of the purified protein indicated that the conditions required for its expression and possibly the purification method adopted, can consistently affect the expression of the protein as nitrite or selenite reductase. While the reduction of nitrite has been successfully verified, medium-long periods of time are required to obtain the right amount of the purified enzyme to be used in all the possible expression conditions.

Abstract (italiano)

Rhizobium sullae, un batterio azotofissatore, induce la formazione di noduli radicali in Hedysarum coronarium L., una leguminosa foraggiera conosciuta in Italia con il nome di sulla e spontanea in quasi tutto il bacino del Mediterraneo, considerato il suo areale d’origine.
Sebbene la capacità di denitrificare possa essere utile alla sopravvivenza e alla crescita delle cellule batteriche in ambienti anossici, il processo di denitrificazione tra i rizobi è piuttosto raro. Soltanto B. japonicum e A. caulinodans si comportano come i veri denitrificanti, riducendo il nitrato (NO3-) simultaneamente a NH4+(assimilazione) e N2 (denitrificazione), quando fatti crescere, in condizioni di microaerofilia, in colture contenenti nitrato come sola fonte di azoto. R sullae strain HCNT1 ha dimostrato di possedere una nitrito riduttasi contenente rame (Cu-Nir), in grado di produrre ossido nitrico (NO) e codificata dal gene nirK, mentre non possiede invece l’ossido nitrico riduttasi e gli altri enzimi richiesti per il processo completo di denitrificazione.
L’espressione del gene nirK è atipica e unica nel suo genere, poiché non richiede la presenza del suo substrato, il nitrito (NO2-), ma soltanto di una diminuzione della concentrazione di ossigeno in una fase di induzione. La riduzione del nitrito da parte del ceppo HCNT1 provoca l’inibizione della crescita cellulare, a causa dell’accumulo di NO a livelli tossici per la cellula microbica, a conferma che R. sullae non contiene l’enzima Nor (ossido nitrico reduttasi). Il processo di nodulazione, la crescita della pianta ospite e la capacità azoto-fissatrice del ceppo wild-type sono del tutto simili a quelle riscontrate nei ceppi mutanti nirK-.
L’esistenza di un ruolo fisiologico per la catena di denitrificazione interrotta riscontrata in R. sullae non ha in realtà una spiegazione ovvia. È possibile che l’attività dell’enzima Nir permetta alle cellule batteriche di convertirsi nella forma VBNC (viable-but-not-culturable), in modo tale che possano sopravvivere in condizioni di stress anche per lunghi periodi, senza perdere tuttavia la capacità di riprendere lo stato vegetativo.
Recentemente il ceppo HCNT1 ha dimostrato di possedere la capacità di crescere in presenza di alte concentrazioni di selenito (50 mM); inoltre, durante la crescita, il selenito è stato ridotto a selenio elementare non tossico e di colore rosso.
Un ceppo mutante di HCNT1, HCAT2, privo del gene per la nitrito riduttasi, non ha mostrato tuttavia la stessa capacità del wild-type di ridurre il selenito, non essendo in grado di crescere in mezzi colturali contenenti selenito 25 o 50 mM, o avendo scarsa capacità di crescere anche in presenza di basse concentrazioni di selenito (5 mM).
Un altro ceppo di R. sullae, denominato A4, è stato isolato dallo stesso suolo dove in precedenza era stato isolato il ceppo HCNT1. Il ceppo A4 ha mostrato un comportamento molto simile a HCNT1 per quanto riguarda la risposta alla presenza del selenito nel mezzo di coltura, mentre il mutante A4 nirK- un comportamento più simile a quello del ceppo HCAT2. La mancanza del gene nirK sembra quindi rendere i ceppi molto più sensibili alla presenza dell’ossianione del selenio.
A confermare questa evidenza, un ceppo wild-type privo del gene nirK, R. sullae CC1335, isolato in un ambiente diverso da quello di HCNT1 e A4, ha mostrato la sua incapacità di crescere in presenza di selenito. D’altra parte, il trasferimento del gene nirK di HCNT1 nel ceppo CC1335 ha contribuito ad incrementare la sua resistenza a questo ossianione.
I dati raccolti in questi esperimenti hanno suggerito, quindi, la possibilità che la nitrito riduttasi di R. sullae possa far parte di un meccanismo responsabile della resistenza al selenito, indicando una spiegazione plausibile per l’esistenza della catena di denitrificazione radicalmente troncata e riscontrata unicamente in questo batterio.
Tenendo presente la capacità di Nir di ridurre differenti ossianioni oltre al nitrito, come ad esempio il selenito, è stato proposto per questo enzima un meccanismo di multifunzionamento, ovvero la proteina Nir potrebbe agire da nitrito o da selenito riduttasi in base al substrato e alle condizioni aerobiche o anaerobiche in cui si trova il microrganismo.
Al fine di supportare quest’ultima ipotesi, sono state valutate le possibili correlazioni esistenti tra i sistemi di riduzione dei due ossianioni.
In particolare è stato dimostrato che la riduzione del selenito avviene sia in condizioni aerobiche che anaerobiche, e che si tratta di una attività enzimatica costitutiva, a differenza dell’attività nitrito riduttasica, la quale richiede un periodo di induzione in condizioni limitanti di ossigeno. È stato riscontrato, inoltre, che l’aggiunta di nitrito in una coltura già contenente selenito non interferisce con la riduzione di quest’ultimo ossianione alla forma elementare del selenio. Al contrario, l’aggiunta di selenito a colture già contenenti nitrito ha mostrato di inibire la produzione degli ossidi di azoto, nei casi in cui venga aggiunto prima, durante o dopo la fase di incubazione in microaerofilia.
L’utilizzo di uno specifico chelante delle nitrito reduttasi contenenti rame (Cu-Nir) insieme al selenito contenuto nel un mezzo colturale, ha rivelato che l’enzima responsabile della riduzione del selenito in R. sullae contiene rame, poiché l’attività selenito reduttasica viene inibita e non vi è formazione del colore rosso.
Si è dunque reso necessario procedere alla purificazione della proteina al fine di studiarne più in dettaglio le proprietà. Ciò ha comportato la ricerca di una strategia adeguata che facesse uso di un sistema biologico appropriato. E. coli, generalmente utilizzato a questo scopo, ha mostrato di possedere vie metaboliche che portano alla riduzione del selenito a selenio elementare. Al fine di procedere in maniera inequivocabile alla produzione e purificazione della proteina è stato quindi necessario ricorrere alla costruzione di una proteina ricombinante marcata con istidina (6xHis) per l’espressione in E. coli, per poter poi procedere alla purificazione per affinità. Ciò ha comportato un ritardo imprevisto sulla tabella di marcia delle attività di dottorato. Tuttavia la proteina Nir è stata infine purificata e sono stati condotti saggi in vitro per testarne l’effettiva capacità di ridurre il nitrito e il selenito separatamente. In tal modo è possibile chiarire se la nitrito e la selenito riduttasi sono la stessa proteina che lavora in modo diverso a seconda del substrato e delle condizioni in cui si trovano le cellule batteriche, o se si tratta di due proteine distinte che lavorano indipendentemente. L’approccio preliminare che è stato possibile attuare su una prima frazione di proteina purificata ha indicato che le condizioni di espressione e il metodo di purificazione possono avere una grande influenza sull’espressione stessa. Mentr la riduzione del nitrito è stato già verificata con successo, occorreranno tempi un po’ più lunghi per ottenere discrete quantità dell’enzima da utilizzare in tutte le potenziali condizioni di espressione.

Statistiche Download - Aggiungi a RefWorks
Tipo di EPrint:Tesi di dottorato
Relatore:CASELLA, SERGIO
Dottorato (corsi e scuole):Ciclo 21 > Scuole per il 21simo ciclo > SCIENZE DELLE PRODUZIONI VEGETALI > AGROBIOTECNOLOGIE
Data di deposito della tesi:28 Gennaio 2009
Anno di Pubblicazione:2009
Parole chiave (italiano / inglese):denitrification copper-nitrite reductase selenite reductase Rhizobium sullae HCNT1
Settori scientifico-disciplinari MIUR:Area 07 - Scienze agrarie e veterinarie > AGR/16 Microbiologia agraria
Struttura di riferimento:Dipartimenti > Dipartimento di Biotecnologie Agrarie
Codice ID:1558
Depositato il:28 Gen 2009
Simple Metadata
Full Metadata
EndNote Format

Bibliografia

I riferimenti della bibliografia possono essere cercati con Cerca la citazione di AIRE, copiando il titolo dell'articolo (o del libro) e la rivista (se presente) nei campi appositi di "Cerca la Citazione di AIRE".
Le url contenute in alcuni riferimenti sono raggiungibili cliccando sul link alla fine della citazione (Vai!) e tramite Google (Ricerca con Google). Il risultato dipende dalla formattazione della citazione.

Adman, E.T. (1991) Copper protein structures. Adv Protein Chem 42: 145-197. Cerca con Google

Adman, E.T., Godden, J.W., Turley, S. (1995) The structure of copper-nitrite reductase from Achromobacter cycloclastes at five pH value, with NO2- bound and with type II copper depleted. J Biol Chem 270: 27458-27474. Cerca con Google

Anders, H.J., Kaetzke, A., Kämpfer, P., Ludwig, W., Fuchs, G. (1995) Taxonomic position of aromatic-degrading denitrifying pseudomonad strains K 172 and KB 740 and their description as a new members of the genera Thauera, as Thauera aromatica sp. nov., and Azoarcu, as Azoarcus evansii sp. nov., respectively, members of the beta subclass of the Proteobacteria. Int J Syst Bacteriol 45: 327-333. Cerca con Google

Basaglia, M., Toffanin, A., Corich, V., Vian, P., Concheri, G., Giacomini, A., Squartini, A., Nuti, M.P., Casella, S. (1997) in IMPACT 2 Contractors meeting, Granada, Spain, pp.19-20. Cerca con Google

Basaglia, M., Toffanin, A., Shapleigh, J.P., Baldan, E., Casella, S. (2004) Elucidating the cause and the effect of NO accumulation in R. sullae strain HCNT1. Cost Action 856: Ecological Aspects of Denitrification with Emphasis on Agriculture. March 25th- 28th (pp.56), Marburg, Germany. Cerca con Google

Basaglia, M., Toffanin, A., Baldan, E., Bottegal, M., Shapleigh, J.P., Casella, S. (2007) Selenite-redicing capacity of the copper- containing nitrite reductase of Rhizobium sullae. FEMS Microbiol Lett 269(1): 124-130. Cerca con Google

Basaglia, M., Povolo, S., Casella, S. (2007) Resuscitation of viable but not culturable Sinirhizobium meliloti 41 pRP4-luc: effect of oxygen and host plant. Curr Microbiol 54(3): 167-174. Cerca con Google

Bazylinski, D.A., Blakemore, R.P. (1983) Denitrification and assimilatory nitrate reduction in Aquaspirillum magnetotacticum. Appl Environ Microbiol 46: 1118-1124. Cerca con Google

Berendes, F., Gottschalk, G., Heine-Dobbernack, E., Moore, E.R.B., Tindall, B.J. (1996) Halomonas desiderata sp. nov., a new alkaliphilic halotolerant and denitrifying bacterium isolated from a municipal sewage works. Syst Appl Microbiol 19: 158-167. Cerca con Google

Berks, B.C., Richardson, D.J., Ferguson S.J. (1993) Purification and characterization of a nitrous oxide reductase from Thiosphera pantotropha. Implication for the mechanism of aerobic nitrous oxide reduction. Europ J Biochem 212: 467-476. Cerca con Google

Berks, B.C., Ferguson S.J., Moir J.W.B., Richardson D.J. (1995) Enzymes and associated electron transport systems that catalyse the respiratory reduction of nitrogen oxides and oxyanions. Biochem Biophys Acta 1232: 97-173. Cerca con Google

Bogossian, G.L.E., Sammons, P.J.L., Morris, J.P., O’Neil, M.A., Heitkamp, M.A., Weber, D.B. (1996) Death of the Escherichia coli K-12 strain W3110 in soil and water. Appl Environ Microbiol 62: 4114-4120. Cerca con Google

Bradford, M.M. (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72: 248-252. Cerca con Google

Brown, G.C. (1995) Nitric oxide regulates mithchondrial respiration and cell functions by inhibiting cytochrome oxidase. FEBS Lett 369: 136-139. Cerca con Google

Callaham, D. A., Torrey, J.G. (1981) The structural basis for infection of root hairs of Trifolium repens by Rhizobium. Can J Bot 59:1647–1664. Cerca con Google

Casella, S., Gault, R.R., Reynolds, K.C., Dyson, J.R., Brockwell, J. (1984) Nodulation studies on legume exotic to Australia: Hedysarum coronarium L. FEMS Microbiol Letters 22:37-45. Cerca con Google

Casella, S., Shapleigh, J.P., Payne, W.J. (1986) Nitrite reduction in Rhizobium “hedysari” strain HCNT1. Arch Microbiol 146: 233-238. Cerca con Google

Casella, S., Shapleigh, J.P., Lupi, F., Payne, W.J. (1988) Nitrite reductase in bacteroids of Rhizobium “hedysari” strain HCNT1. Arch Microbiol 149: 384-388. Cerca con Google

Casella, S., Fontana, F., Povolo, S., Basaglia, M. (2001) in ISME-9, 9th International Symposium on Microbial Ecology, Amsterdam, The Netherlands, p.191. Cerca con Google

Casella, S., Shapleigh, J.P., Toffanin, A, Basaglia, M. (2006) Investigation into the role of the truncated denitrification chain in R. sullae strain HCNT1. Biochem Soc Trans 34(1): 130-132. Cerca con Google

Cassab, G. I. (1998) Plant cell wall proteins. Annu Rev Plant Physiol Plant Mol Biol 49: 281–309. Cerca con Google

Causey, M.B., Beane, K.N., Wolf, J.R. (2006) The effects of salinity and other factors on nitrite reduction by Ochrobactrum anthropi 49187. J Basic Microbiol 46(1): 10-21. Cerca con Google

Chan, Y.K., Barraquio, W.L., Knowles, R. (1994) N2-fixing pseudomonads and related soil bacteria. FEMS Microbiol Rev 13: 95-117. Cerca con Google

Coyle, C.L., Zumft, W.G., Kroneck, P.M.H., Körner, H., Jacob, W. (1985) Nitrous oxide reductase from denitrifying Pseudomonas perfectomarina. Purification and properties of a novel multicopper enzyme. Europ J Biochem 153: 459-467. Cerca con Google

Cosgrove, D.J., P. Bedinger, P., Durachko, D.M. (1997) Group I allergens of grass pollen as cell wall-loosening agents. Proc. Natl. Acad. Sci. USA 94: 6559–6564. Cerca con Google

Cosgrove, D. J., Li, L.C., Cho, H.T., Hoffmann-Benning, S., Moore, R.C., Blecker, D. (2002) The growing world of expansins. Plant Cell Physiol 43: 1436–1444. Cerca con Google

Cutruzzolà, F. (1999) Bacterial nitric oxide synthesis . Biochem Biophys Acta 1411: 231-249. Cerca con Google

Danneberg, G., Kronenberg, A., Neuer, G., Bothe, H. (1985) Aspects of nitrogen fixation and denitrification bt Azospirillum. Plant Soil 90: 193-202. Cerca con Google

Danneberg, G., Zimmer, W., Bothe: H. (1989) Energy transduction efficiencies in nitrogenous oxide respirations of Azospirillum brasilense Sp.7. Arch Microbiol 151: 445-453. Cerca con Google

DeMoll-Decker, H., Macy, J.M. (1993). The periplasmic nitrite reductase of Thauera selenatis may catalyze the reduction of selenite to elemental selenium. Arch Microbiol 160: 241–247. Cerca con Google

De Vos, P., Van Landschoot, A., Segers, P., Tytgat, R., Gillis, M., Bawens, M., Rossau, R., Goor, M., Pot, B., Kersters, K., Lizzaraga, P., De Ley, J. (1989) Genotypic relationships and taxonomic localization of unclassified Pseudomonas and Pseudomonas-like strains by deoxyribonucleic acid: ribosomal ribonucleic acid hybridizations. Int J Syst Bacteriol 39: 35-49. Cerca con Google

Dodd, F.E., Hasnain, S.S., Abraham, Z.H.L., Ready, R.R., Smith, B.E. (1997) Structure of a blue-copper nitrite reductase and its substrate-bound complex. Acta Crystallogr Sect D 53: 406-418. Cerca con Google

Dodd, F.E., van Beeumen, J., Eady, R.R., Hasnain, S.S. (1998) X-ray structure of a blue-copper nitrite reductase in two crystal forms. The nature of the copper sites, mode of substrate binding and recognition by redox partner. J Mol Biol 282: 369-382. Cerca con Google

Doran, J.W. (1982) Microorganisms and biological cycling of selenium. Adv Microbial Ecol 6: 17-32. Cerca con Google

Dower, W., Miller, J.F., Ragsdale, C.W. (1998) High efficiency transformation of the E. coli by high voltage electroporation. Nucl Acid Res 16: 6127-6145. Cerca con Google

Dungan, R.S., Frankenberger, W.T.J. (1999) Microbial transformations of selenium and the bioremediation of seleniferous environments. Bioremediation J 3: 171-88. Cerca con Google

Dunstan, R.H., Kelley, B.C., Nicholas, D.J.D. (1982) Fixation of dinitrogen derived from denitrification of nitrate in a photosynthetic bacterium, Rhodopseudomonas sphaeroides forma sp. denitrificans. J Bacteriol 150: 100-104. Cerca con Google

Einsle, O., Kroneck, P.M. (2004) Structural basis of denitrification. Biol Chem 385: 875-883. Cerca con Google

Farabaugh, J.P. (1978) Sequence of the lacI gene. Nature 274-765. Cerca con Google

Favre-Bonte, S., Ranjard, L., Colinon, C., Prigent-Combaret, C., Nazaret, S., Cournoyer, B. (2005) Freshwater selenium-methylating bacterial thiopurine methyltransferases: diversity and molecular phylogeny. Environ Microbiol 7: 153-64. Cerca con Google

Frankenberger, W.T., Karlson, U. in: W.T Frankenberger, S. Benson (eds.) Selenium in the environment, Marcel Dekker, New York, 1994, p. 369. Cerca con Google

Frunzke, K., Meyer, O. (1990) Nitrate respiration, denitrification and utilization of nitrogen sources by aerobic carbon monoxide- oxidizing bacteria. Arch Microbiol 154: 168-174. Cerca con Google

Gadd, G.M. (1993) Microbial formation and transformation of organometallic and organometalloid compounds. FEMS Microbiol Rev 11: 297-316. Cerca con Google

Gage, D.J. (2004) Infection and invasion of roots by symbiotic, nitrogen-fixing rhizobia during nodulation of temperate legumes. Microbiol Molec Biol Rev 68(2): 280-300. Cerca con Google

Ganther, H.E., Levander, O.A., Sauman, C.A. (1966) Dietary control of selenium volatilization in the rat. J Nutr 88: 55-60. Cerca con Google

Garcia-Plazaola, J.I., Becerril, J.M., Arrese-Igor, C., Gonzales-Murua, C., Aparicio-Tejo, P.M. (1993) Denitrifying ability of thirteen Rhizobium meliloti strains. Plant and Soil 157: 207-213. Cerca con Google

Garcin, E., Vernede, X., Hatchikian, E.C., Volbeda, A., Frey, M., Fontecilla-Camps, J.C. (1999) The crystal structure of a reduced [NiFeSe] hydrogenase provides an image of the activated catalytic center. Struct Fold Des 7: 557–66. Cerca con Google

Gattow, G., Heinrich, G. (1964) Thermochemistry of selenium. II. Conversion of crystalline selenium modification. III. Conversion of amorphous selenium modifications. Z Anorg Allg Chem 331: 256-288. Cerca con Google

Geering, H.R., Cary, E.E., Jones, L.H.P., Allaway, W.H. (1968) Solubility and redox criteria for the possible forms of selenium in soils. Soil Sci Soc Am Proc 32: 35-40. Cerca con Google

Godden, J. W., Turley, S., Teller, D.C., Adman, E.T., Liu, M.Y., Payne, W.J., LeGall, J. (1991) The 2.3 angstrom X-ray structure of nitrite reductase from Achromobacter cycloclastes. Science 253: 438-442. Cerca con Google

Goretski, J., Hollocher, T.C. (1988) Trapping of nitric oxide produced during denitrification by extracellular haemoglobin. J Biol Chem 263: 2316-2323. Cerca con Google

Hamdi, Y.A. (1968) Reduction of sodium tellurite by different strains of Agrobacterium and Rhizobium. Acta Microbiol Pol 17: 203-206. Cerca con Google

Heider, J., Böck, A. (1993) Selenium metabolism in microorganisms. Adv Physiol 35: 74-107. Cerca con Google

Herbel, M.J., Switzer Blum, J., Oremland, R.S., Borglin, S.E. (2003) Reduction of elemental selenium to selenide: experiments with anoxic sediments and bacteria that respire Se-oxyanions. Geomicrobiol J 20: 587-602. Cerca con Google

Hernandez, D., Rowe, J.J. (1988) Oxygen inhibition of nitrate uptake is a general regulatory mechanism in nitrate respiration. J Biol Chem 263: 7937-7939. Cerca con Google

Hiraishi, A., Ueda, Y. (1994) Intrageneric structure of the genus Rhodobacter: transfer of Rhodobacter sulfidophilus and related marine species to the genus Rhodovulum gen. nov. Int J Syst Bacteriol 44: 15-23. Cerca con Google

Honisch, U., Zumft, W.G. (2003) Operon structure and regulation of the nos gene region of Pseudomonas stutzeri, encoding an ABC-Type ATPase for maturation of nitrous oxide reductase. J Bacteriol 185(6): 1895-1902. Cerca con Google

Huber, R., Wilharm, T., Huber, D., Trincone, A., Burggraf, S., König, H., Rachel, R., Rockinger, I., Fricke, H., Stetter, K.O. (1992) Aquifex pyrophilus gen. nov., represent a novel group of marine hyperthermophilic hydrogen-oxidizing bacteria. Syst Appl Microbiol 15: 340-351. Cerca con Google

Hughes, M.N. (1999) Relationship between nitric oxide, nitroxyl ion, nitrosonium cation and peroxynitrite. Biochem et Biophys Acta 1411: 263-272. Cerca con Google

Hunter, W.J., Kuykendall, L.D. (2007) Reduction of selenite to elemental red selenium by Rhizobium sp. strain B1. Curr Microbiol 55: 344-349. Cerca con Google

Ingraham, J. L. (1981) Microbiology and genetics of denitrifiers. Pages 45-65 in C. C. Delwiche ed. Denitrification, Nitrification, and Atmosphere Nitrous Oxide. Wiley-Interscience, Ney York. Cerca con Google

Keen, N T., Tamaki, S., Kobayashi, D., Trollinger, D. (1988) Improved broad-host range plasmid for DNA cloning in Gram-negative bacteria. Gene 70: 191-197. Cerca con Google

Kessi, J. (2006) Enzymatic systems proposed to be involved in the dissimilatory reduction of selenite in the purple non sulfur bacteria Rhodospirillum rubrum and Rhodobacter capsulatus. Microbiol 152: 731-743. Cerca con Google

Kinkle, B.K., Sadowsky, M.J., Johnstone, K., Koskinen, W.C. (1994) Tellurium and selenium resistance in rhizobia and its potential use for direct isolation of Rhizobium meliloti from soil. Appl Environ Microbiol 60: 1674-1677. Cerca con Google

Krafft, T., Bowen, A., Theis, F., Macy, J.M. (2000) Cloning and sequencing of the genes encoding the periplasmic-cytochrome b-containing selenate reductase of Thauera selenatis. DNA Sequation 10: 365-77. Cerca con Google

Kukimoto, M., Nishiyama, M., Murphy, M.E.P., Turley, S., Adman, E.T., Horinouchi, S., Beppu, T. (1994) X-ray structure and site-directed mutagenesis of a nitrite reductase from Alcaligenes faecalis S-6: role of two copper atoms in nitrite reduction. Biochem 33: 5246-5252. Cerca con Google

Laemmli, U.K. (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature (London) 227: 680-685. Cerca con Google

Lin, J.T., Goldman, B.S., Stewart, V. (1994) The nasFEDCBA operon for nitrate and nitrite assimilation in Klebsiella pneumoniae M5a1. J Bacteriol 176: 2551-2559. Cerca con Google

Linder, K., Oliver, J.D. (1989) Membrane fatty acid and virulence changes in the viable but not culturable state of Vibrio vulnifcus. Appl Environ Microbiol 55: 2837-2842. Cerca con Google

Maher, M.J., Santini, J., Pickering, I.J., Prince, R.C., Macy, J.M., George, G.N. (2004) X-ray absorption spectroscopy of selenate reductase. Inorg Chem 43: 402-4. Cerca con Google

Meyer, O., Frunzke, K., Gadkari, D., Jacobitz, S., Hugendieck, I., Kraut, M. (1990) Utilization of carbon monoxide by aerobes: recent advances. FEMS Microbiol Rev 87: 253-260. Cerca con Google

Miller, J. (1972) Experiments in Molecular Genetics, p. 352-355. Cold Spring Harbor Laboratory, NY. Cerca con Google

McCarty, S., Chasteen, T., Marshall, M., Fall, R., Bachofen, R. (1993) Phototrophic bacteria produce volatile, methylated sulfur and selenium compounds. FEMS Microbiol Lett 112: 93-98. Cerca con Google

McDougald, D., Rice, S.A., Weichart, D., Kjelleberg, S. (1998) Nonculturability: adaptation or debilitation? FEMS Microbiol Ecol 25:1-9. Cerca con Google

McGovern, V.P., Oliver, J.D. (1995) Induction of cold-responsive proteins in Vibrio vulnificus. J Bacteriol 177: 4131-4133. Cerca con Google

Moore, M.D., Kaplan, S. (1992) Identification of intrinsic high-level resistance to rare-earth oxides and oxyanions in members of the class Proteobacteria: characterization of tellurite, SeIV, and rhodium sesquioxidic reduction in Rhodobacter sphaeroides. J Bacteriol 174: 1505-1514. Cerca con Google

Muckopadhyay, P., Zheng, M., Bedzyk, L.A., LaRossa, R.A., Storz, G. (2004) Prominent roles of the NorR and Fur regulators in the Escherichia coli transcriptional response to Cerca con Google

reactive nitrogen species. Proceedings of the National Academy of Science 101: 745-750. Cerca con Google

Mukamolova, G.V., Kormer, S.S., Yanopolskaya, N.D., Kaprelyants, A.S. (1995) Properties of dormant cells in stationery-phase cultures of Micrococcus luteus during prolonged incubations. Mikrobiologiya 64: 284-288. Cerca con Google

Nicholls, D.G., Ferguson, S.J. (2002) Bioenergetics 3, Academic Press, London/San Diego. Cerca con Google

O’Hara, G.M., Daniel, R.M. (1985) Rhizobial denitrification: A review. Soil Biol Biochem 17:1-9. Cerca con Google

Ohlendorf, H.M. (1989) Bioaccumulation and effects of selenium in wildlife. P. 133-177 in L. W. Jacobs (ed.), Selenium in agriculture and the environment. American Society of Agronomy, Madison, Wis. Cerca con Google

Oliver, J.D. (1993) Formation of viable but nonculturable cells. In: Starvation of bacteria, Kjelleberg, S. (ed.). Plenum Press, New York, pp. 239-272. Cerca con Google

Oliver, J.D., Hite, F., McDougald, D., Andon, N.L., Simpson, L.M. (1995) Entry into, and resuscitation from, the viable but nonculturable state by Vibrio vulnificus in an estuarine environment. Appl Environ Microbiol 61: 2624-2630. Cerca con Google

Oremland, R.S., Zehr, J.P. (1986) Formation of methane and carbon dioxide from dimethylselenide in anoxic sediments and by a methanogenic bacterium. Appl Environ Microbiol 52: 1031-36. Cerca con Google

Payne, W. J. (1981) Denitrification. Wiley-Interscience, New York. Cerca con Google

Penfold, R. J. and Pemberton, M. (1992) An improved suicide vector for construction of chromosomal insertion mutations in bacteria. Gene 118: 145-146. Cerca con Google

Pinsent, J. (1954) Need for selenite and molybdate in the formation of formic dehydrogenase by members of the Escherichia coli-Aerobacter aerogenes group of bacteria. Biochem J 57:10-16 Cerca con Google

Plotnikov, V.I. (1958) coprecipitation of small quantities of selenium with ferric hydroxide. Zh Neog Klim 3: 1761-1766. Cerca con Google

Poole, R.K. (2005) Nitric oxide and nitrosative stress tolerance in bacteria. Biochem Soc Trans 33(1): 176-180. Cerca con Google

Ranjard, L., Prigent-Combaret, C., Nazaret, S., Cournoyer, B. (2002) Methylation of inorganic and organic selenium by the bacterial thiopurine methyltransferase. J Bacteriol 184: 3146-49. Cerca con Google

Ranjard, L., Nazaret, S., Cournoyer, B. (2003) Freshwater bacteria can methylate selenium through the thiopurine methyltransferase pathway. Appl. Environ. Microbiol. 69: 3784-90. Cerca con Google

Ranjard, L., Prigent-Combaret, C., Favre-Bonte, S., Monnez, C., Nazaret, S., Cournoyer, B. (2004) Characterization of a novel selenium methyltransferase from freshwater bacteria showing strong similarities with the calicheamicin methyltransferase. Biochem Biophys Acta 1679: 80-85. Cerca con Google

Roszak, D.B., Colwell, R.R. (1987) Survival strategies of bacteria in the natural environments. Microbiol Rev 51: 365-379. Cerca con Google

Rozen, S., Skaletsky, H.J. (1998) Primer3 Code available at http://www.-genome.wi.mit.edu/genomesoftware/other/primer3.html Vai! Cerca con Google

Sabaty, M., Avazeri, C., Pignol, D., Vermiglio, A. (2001) Characterization of the reduction of selenate and tellurite by nitrate reductase. Appl Environ Microbiol 67(11): 5122-5126. Cerca con Google

Sambrook, J., Fritsch, E.F., Maniatis, T. (1989) Molecular Cloning: A Laboratory Manual, second ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor. Cerca con Google

Samuelsson, M.O. (1985) Dissimilatory nitrate reduction to nitrite, nitrous oxide and ammonium by Pseudomonas putrefaciens. Appl Environ Microbiol 50: 812-815. Cerca con Google

Satoh, T., Hoshino, Y., Kitamura, H. (1976) Rhodopseudomonas sphaeroides forma sp. denitrificans, a denitrifying strain as a subspecies of Rhodopseudomonas sphaeroides. Arch Microbiol 108: 265-269. Cerca con Google

Sayato, Y., Nakamuro, K., Hasegawa, T. (1997) Selenium methylation and toxicity mechanism of selenocysteine. Yakugaku Zasshi 117: 665-72. Cerca con Google

Sias, S.R., Stouthamer, A.H., Ingraham, J.L. (1980) The assimilatory and dissimilatory nitrate reductase of Pseudomonas aeruginosa are encoded by different genes. J Gen Microbiol 118: 229-234. Cerca con Google

Shrift, A. (1973) Metabolism of selenium by plants and microrganisms, in: D.L. Klayman e W.H. Gunther (eds.) Organic selenium compounds: their chemistry and biology, pp. 763-814, John Wiley & Sons, New York. Cerca con Google

Smil, V. (1999) Nitrogen in crop production: An account of global flows. Global Biogeochem Cycles 13: 647-662. Cerca con Google

Schröder, I., Rech, S., Krafft, T., Macy, J.M. (1997) Purification and characterization of the selenate reductase from Thauera selenatis. J Biol Chem 272: 23765-68. Cerca con Google

Snyder, S.W., Hollocher, T.C. (1987) Purification and some characteristics of nitrous oxide reductase from Paracoccus denitrificans. J Biol Chem 262:6515-6525. Cerca con Google

de Souza, M.P., Lytle, C.M., Mulholland, M.M., Otte, M.L., Terry, N. (2000) Selenium assimilation and volatilization from dimethylselenonioproprionate by Indian mustard. Plant Physiol 122: 1281-88. Cerca con Google

Squartini, A., Struffi, P., Doering, H., Selenska-Pobell, S., Tola, E., Giacomini, A., Vendramin, E., Velasquez, E., Mateos, P., Martinez-Molina, E., Dazzo, F.B., Casella, S., Nuti, M.P. (2002) Rhizobium sullae sp. nov. (formerly Rhizobium ‘hedysari’): the root-nodule microsymbiont of Hedysarum coronarium L. Int J Syst Evol Microbiol 52: 1267-1276. Cerca con Google

Stewart, V., Parales, J. (1988) Identification and expression of genes and narX of the narc (nitrate reductase) locus in Escherichia coli K-12. J Bacteriol 170: 1589-1597. Cerca con Google

Stolz, J.F., Oremland, R.S. (1999) Bacterial respiration of arsenic and selenium. FEMS Microbiol Rev 23: 615-27. Cerca con Google

Storz, G., Hengee-Aronis, R. (2000) Bacterial stress responses. ASM Press, NY, pp 485. Cerca con Google

Strange, R.W., Dodd, F.E., Abraham, Z.H.L., Grossmann, J.G., Brüser, T., Eady, R.R., Smith, B.E., Hasnain, S.S. (1995) The substrate-binding site in Cu nitrite reductase and its similarity to Zn carbonic anhydrase. Nat Struct Biol 2(4): 287-292. Cerca con Google

Straub, K.L., Benz, M., Schink, B., Widdel, F. (1996) Anaerobic, nitrate- dependent microbial oxidation of ferrous iron. Appl Environ Microbiol 62: 1458-1460. Cerca con Google

Strous, M., Fuerst, J.A., Kramer, E.H., Logemann, S., Muyzer, G., van de Pas-Schoonen, K.T., Webb, R., Kuenen, J.G., Jetten, M.S.M. (1999) Missing lithotroph identified as new planctomycetes. Nature 400: 446-449. Cerca con Google

Switzer Blum, J., Bindi, A.B., Buzzelli, J., Stolz, J.F., Oremland, R.S. (1998) Bacillus arsenoselenatis sp. nov., and Bacillus selenitireducens sp. nov.: two haloalkaliphiles from Mono Lake, California, which respire oxyanions of selenium and arsenic. Arch Microbiol 171: 19-30. Cerca con Google

Takai, K., Kobayashi, H., Nealson, K.H., Horikoshi, K. (2003) Deferribacter desulfuricans sp. nov., a novel sulfur-, nitrate- and arsenate-reducing thermophile isolated from a deep-sea hydrothermal vent. Int J Syst Evol Microbiol 53: 839-46. Cerca con Google

Tavares, P., Pereira, A.S., Moura, J.J.G., Moura, I. (2006) Metalloenzyme of denitrification pathway. J Inorg Biochem 100: 2087-2100. Cerca con Google

Toffanin, A., Wu, Q., Maskus, M., Casella, S., Abruña, H.D., Shapleigh, J.P. (1996) Characterization of the gene encoding nitrite reductase and the physiological consequences of its expression in the non-denitrifying Rhizobium “hedysari” strain HCNT1. Appl Environ Microbiol 62: 4019-4025. Cerca con Google

Toffanin, A., Basaglia, M., Ciardi, C., Vian, P., Povolo, S., Casella, S. (2000) Energy content decrease and viable-but-not-culturable status induced by oxygen limitation couplet to the presence of nitrogen oxides in Rhizobium “hedysari”. Biol Fertil Soil 31: 484-488. Cerca con Google

Trutko, S.M., Akimenko, V.K., Suzina, N.E., Anisimova, L.A., Shlyapnikov, M.G., Baskunov, B.P. (2000) Involvement of the respiratory chain of gram-negative bacteria in the reduction of tellurite. Arch Microbiol 173: 178-186. Cerca con Google

Turner, R.J.,Weiner, J.H.,Taylor, D.E. (1998) Selenium metabolism in Escherichia coli. Biometals 11: 223-27. Cerca con Google

Van den Bosch, K. A., Bradley, D.J., Knox, J.P., Perotto, S., Butcher, G.W., Brewin, N.J. (1989) Common components of the infection thread matrix and intercellular space identified by immunocytochemical analysis of pea nodules and uninfected roots. EMBO J. 8: 335–342. Cerca con Google

Van de Graaf, A.A., Mulder, A., Debruijn, P., Jetten, M.S.M., Robertson, L.A., Kuenen, J.G. (1995) Anaerobic oxidation of ammonium is a biologically mediated process. Appl Environ Microbiol 61: 1246-1251. Cerca con Google

van Spronsen, P.C., Bakhuizen, R., van Brussel, A.A.N., Kijne, J.W. (1994) Cell-wall degradation during infection thread formation by the rootnodule bacterium Rhizobium leguminosarum is a 2-step process. Eur J Cell Biol 64: 88-94. Cerca con Google

van Workum, W.A.T., van Slageren, S., van Brussel, A.A.N., Kijne, J.W. (1998) Role of exopolysaccharides of Rhizobium leguminosarum bv. viciae as host plant-specific molecules required for infection thread formation during nodulation of Vicia sativa. Mol Plant-Microbe Interact 11: 1233-1241. Cerca con Google

Völkl, P., Huber, R., Drobner, E., Rachel, R., Burggraf, S., Trincone, A., Stetter, K.O. (1993) Pyrobaculum aerophilum sp. nov., a novel nitrate -reducing hyperthermophilic archaeum. Appl Environ Microbiol 59: 2918-2926. Cerca con Google

Warnecke-Eberz, U., Friedrich, B. (1993) Three nitrate reductase activities in Alcaligenes eutrophus. Arch Microbiol 159: 405-409. Cerca con Google

Weichart, D., Kjelleberg, S. (1996) Stress resistance and recovery potential of culturable and viable but not culturable cells of Vibrio vulnificus. Microbiol 142: 845-853. Cerca con Google

Whanger, P.D. (2004) Selenium and its relationship with cancer: an update. Br J Nutr 91: 11-28. Cerca con Google

White, C., Sayer, J.A., Badd, G.M. (1997) Microbial solubilization and immobilization of toxic metals: key biogeochemical processes for treatment of contamination. FEMS Microbiol Rev 20: 503-516. Cerca con Google

Wientjes, F.B., Kolk, A.H.J., Nanninga, N., van’t Riet, J. (1979) Respiratory nitrate reductase: its localization in the cytoplasmic membrane of Klebsiella aerogenes and Bacillus licheniformis. Eur J Biochem 95: 61-67. Cerca con Google

Yamaguchi, K., Takaota, K., Kobayashi, M., Itoh, K.,Fukui, A., Suzuki, S. (2004) Characterization of the two type 1 Cu sites of Hyphomicrobium denitrificans nitrite reductase: a new class of a copper -containing nitrite reductase. Biochem 43: 14180-14188. Cerca con Google

Yan, T., Fields, M.W., Wu, L., Zu, Y., Tiedje, J.M., Zhou, J. (2003) Molecular diversity and characterization of nitrite reductase gene fragments (nirK and nirS) from nitrate- and uranium- contaminated groundwater. Environ Microbiol 5(1): 13-24. Cerca con Google

Young, J.M., Kuykendall, L.D., Martinez-Romero, E., Kerr, A., Sawada, H. (2001) A revision of Rhizobium Frank 1889, with an emended description of the genus, and the inclusion of all species of Agrobacterium Conn 1942 and Allorhizobium undicola de Lajudie et al. 1998 as a new combinations: Rhizobium radiobacter, R. rhizogenes, R. rubi, R. undicola and R. vitis. Int J Syst Evol Microbiol 51:.89-103. Cerca con Google

Young, J.M., Kuykendall, L.D., Martinez-Romero, E., Kerr, A., Sawada, H. (2003) Classification and nomenclature of Agrobacterium and Rhizobium - a reply to Farrand et al., (2003). Int J Syst Evol Microbiol 53: 1689-1695. Cerca con Google

Zhou, J., Fries, M.R., Chee-Sanford, J.C., Tiedje, J.M. (1995) Phylogenetic analyses of a new group of denitrifiers capable of anaerobic growth on toluene and description of Azoarcus tolulyticus sp. nov. Int J Syst Bacteriol 45: 500-506. Cerca con Google

Zieve, R., Ansell, P.J., Young, T.W.K. (1985) Trans Br Mycol Soc 84: 177. Cerca con Google

Zumft, W.G., Viebrock, A., Korner, H. (1988) In: Cole, J.A. and Ferguson, S.J. (eds) The Nitrogen and Sulphur Cycles, pp. 245-279. Cambridge University Press, Cambridge. Cerca con Google

Zumft, W.G. (1992) The denitrifying prokaryotes. In: Balows A, Truper H.G., Dworkin M., Harder W., Schleifer K.H. (eds) The prokaryotes, 2nd edn, Vol 1 (pp 554-582). Springer Verlag, New York. Cerca con Google

Zumft, W.G., Korner, H. (1997) Enzyme diversity and mosaic gene organization in denitrification. Antonie van Leeuwenhoek 71: 43-58. Cerca con Google

Zumft, W.G. (1997) Cell biology and molecular basis of denitrification. Microbiol Mol Biol Rev 61: 533-616. Cerca con Google

Download statistics

Solo per lo Staff dell Archivio: Modifica questo record