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Titolo:
OSMOADAPTATION IN RHIZOBIA - ECTOINE-INDUCED SALT TOLERANCE
Autore:
TALIBART R; JEBBAR M; GOUESBET G; HIMDIKABBAB S; WROBLEWSKI H; BLANCO C; BERNARD T;
Indirizzi:
UNIV RENNES 1,RECH PHYSICOCHIM STRUCT GRP,GENET & PHYSIOL MICROBIENNES,CNRS,URA 704 F-35042 RENNES FRANCE UNIV RENNES 1,RECH PHYSICOCHIM STRUCT GRP,GENET & PHYSIOL MICROBIENNES,CNRS,URA 704 F-35042 RENNES FRANCE UNIV RENNES 1,DEPT MEMBRANES & OSMOREGULAT,CNRS,URA 256 F-35042 RENNES FRANCE
Titolo Testata:
Journal of bacteriology
fascicolo: 17, volume: 176, anno: 1994,
pagine: 5210 - 5217
SICI:
0021-9193(1994)176:17<5210:OIR-ES>2.0.ZU;2-B
Fonte:
ISI
Lingua:
ENG
Soggetto:
BETAINE-BINDING PROTEIN; MEDICAGO-SATIVA L; GLYCINE BETAINE; ESCHERICHIA-COLI; NITROGEN-FIXATION; WATER-STRESS; OSMOTIC-STRESS; HALOPHILIC EUBACTERIA; COMPATIBLE SOLUTES; PROLINE BETAINE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
42
Recensione:
Indirizzi per estratti:
Citazione:
R. Talibart et al., "OSMOADAPTATION IN RHIZOBIA - ECTOINE-INDUCED SALT TOLERANCE", Journal of bacteriology, 176(17), 1994, pp. 5210-5217

Abstract

After having shown that ectoine (a tetrahydropyrimidine) displays osmoprotective properties towards Escherichia coil (M. Jebbar, R. Talibart, K. Gloux, T. Bernard, and C. Bianco, J. Bacteriol. 174:5027-5035, 1992), we have investigated the involvement of this molecule in the osmotic adaptation of Rhizobium meliloti. Ectoine appeared almost as effective as glycine betaine in improving the growth of R. meliloti under adverse osmotic conditions (0.5 M NaCl). Moreover, improvement of growth of rhizobial strains insensitive to glycine betaine was also observed. Ectoine transport proved inducible, periplasmic protein dependent,and, as shown by competition experiments, distinct from the transportof glycine betaine. Medium osmolarity had little effect on the uptakecharacteristics, since the rate of influx increased from 12 to only 20 nmol min(-1) mg of protein(-1) when NaCl concentrations were raised from 0 to 0.3 or 0.5 M, with a constant of transport of 80 mu M. Natural-abundance C-13-nuclear magnetic resonance and radiolabelling assaysshowed that ectoine, unlike glycine betaine, is not intracellularly accumulated and, as a consequence, does not repress the synthesis of endogenous compatible solutes (glutamate, N-acetylglutaminylglutamine amide, and trehalose). Furthermore, the strong rise in glutamate contentin cells osmotically stressed in the presence of ectoine suggests that, instead of being involved in osmotic balance restoration, ectoine should play a key role in triggering the synthesis of endogenous osmolytes. Hence, we believe that there are at least two distinct classes ofosmoprotectants: those such as glycine betaine or glutamate, which act as genuine osmolytes, and those such as ectoine, which act as chemical mediators.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/11/20 alle ore 02:50:59