期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
卷 1798, 期 11, 页码 2141-2149出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbamem.2010.06.022
关键词
Mechanosensitive channel; Corynebacterium; Efflux; Osmoregulation; Uptake; Betaine
资金
- Ajinomoto Co. (Japan)
- Australian Research Council [LX0776077]
- Australian Research Council [LX0776077] Funding Source: Australian Research Council
Based on sequence similarity, the mscCG gene product of Corynebacterium glutamicum belongs to the family of MscS-type mechanosensitive channels. In order to investigate the physiological significance of MscCG in response to osmotic shifts in detail, we studied its properties using both patch-clamp techniques and betaine efflux kinetics. After heterologous expression in an Escherichia coli strain devoid of mechanosensitive channels, in patch-clamp analysis of giant E. coli spheroplasts MscCG showed the typical pressure dependent gating behavior of a stretch-activated channel with a current/voltage dependence indicating a strongly rectifying behavior. Apart from that. MscCG is characterized by significant functional differences with respect to conductance, ion selectivity and desensitation behavior as compared to MscS from E. coli. Deletion and complementation studies in C glutamicum showed a significant contribution of MscCG to betaine efflux in response to hypoosmotic conditions. A detailed analysis of concomitant betaine uptake (by the betaine transporter BetP) and efflux (by MscCG) under hyperosmotic conditions indicates that MscCG may act in osmoregulation in C. glutamicum by fine-tuning the steady state concentration of compatible solutes in the cytoplasm which are accumulated in response to hyperosmotic stress. (C) 2010 Elsevier B.V. All rights reserved.
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