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Titolo:
EFFLUX OF COMPATIBLE SOLUTES IN CORYNEBACTERIUM-GLUTAMICUM MEDIATED BY OSMOREGULATED CHANNEL ACTIVITY
Autore:
RUFFERT S; LAMBERT C; PETER H; WENDISCH VF; KRAMER R;
Indirizzi:
KFA JULICH GMBH,FORSCHUNGSZENTRUM,INST BIOTECHNOL 1,POSTFACH 1913 D-52425 JULICH GERMANY KFA JULICH GMBH,FORSCHUNGSZENTRUM,INST BIOTECHNOL 1 D-52425 JULICH GERMANY
Titolo Testata:
European journal of biochemistry
fascicolo: 2, volume: 247, anno: 1997,
pagine: 572 - 580
SICI:
0014-2956(1997)247:2<572:EOCSIC>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
ESCHERICHIA-COLI; GLYCINE BETAINE; FUNCTIONAL RECONSTITUTION; BREVIBACTERIUM-LINENS; ACTIVATED CHANNELS; OSMOTIC SHOCK; LYSINE UPTAKE; ION CHANNELS; GLUTAMATE; ACCUMULATION;
Keywords:
CORYNEBACTERIUM GLUTAMICUM; OSMOREGULATION; EFFLUX; COMPATIBLE SOLUTES; MECHANOSENSITIVE CHANNEL;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
31
Recensione:
Indirizzi per estratti:
Citazione:
S. Ruffert et al., "EFFLUX OF COMPATIBLE SOLUTES IN CORYNEBACTERIUM-GLUTAMICUM MEDIATED BY OSMOREGULATED CHANNEL ACTIVITY", European journal of biochemistry, 247(2), 1997, pp. 572-580

Abstract

Bacteria respond to hypoosmotic stress by releasing low-molecular-mass solutes in older to maintain constant turgor pressure. We have studied the function of osmoregulated channel(s) in Corynebactium glutamicum which are responsible for efflux of various solutes upon sudden decrease in osmotic pressure. The channels preferentially mediated efflux of compatible solutes such as glycine betaine and proline. The releaseof molecules of similar size. e.g. glutamate or lysine, was restricted, ATP was completely retained even after severe osmotic shock. The cells maintained high cytoplasmic K+ and Na+ concentrations under hypoosmotic shock. Several results suggest that the solute efflux is mediated by a channel and not by a carrier. e.g. by reversal of the glycine betaine uptake systems of C. glutamicum,lf the release of glycine betaine and proline was extremely fast reaching an efflux rate of 6000 mu mol . min(-1). g dm(-1) or higher: the efflux was not significantly influenced by addition of external transport substrate, e.g. glycine betaine; in spite of an extremely high chemical gradient, no significant efflux under isoosmolar conditions was observed: efflux of solutes was unchanged after full uncoupling of membrane energetics by carbonylcyanide m-chlorophenylhydrazone (CCCP). These results indicate the presence of an osmoregulated channel in C. glutamicum similar to the mechanosensitive channel(s) of Escherichia coli. The activity of the channel did not depend on the growth conditions, but we observed a light regulation on the level of activity, i.e. the mechanosensitive channel behaved as a perfect osmometer. By monitoring release of glycine betaine under slow and continuous decrease of the external osmolality, we observed continous efflux without a stepwise release of solutes. This resulted in a significant steady-state decrease ase of the membrane potential.

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Documento generato il 04/07/20 alle ore 21:25:35