SecG plays a critical role in protein translocation in the absence of the proton motive force as well as at low temperature

FEBS Letters

Nishiyama, Ken-ichi¹  Hanada, Mitsuharu¹  Tokuda, Hajime¹ 

[1] Institute of Molecular and Cellular Biosciences, the University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113, Japan

关键词: SecG;    Protein translocation;    Proton motive force;    Membrane vesicle;    E. coli;   

DOI  :  10.1016/0014-5793(96)00066-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

SecG is an integral membrane component of E. coli protein translocase. However, a discrepancy exists as to the importance of SecG for protein translocation at 37°C between cells and reconstituted proteoliposomes; protein translocation in ΔsecG cells is defective at 20°C but normal at 37°C, indicating that SecG is dispensable at 37°C, whereas SecG remarkably stimulates protein translocation into reconstituted proteoliposomes at 37°C. In this study, protein translocation into membrane vesicles containing or not containing SecG was examined in the presence and absence of the proton motive force at 37°C and 20°C. We found that the absence of the proton motive force renders protein translocation strongly dependent on SecG even at 37°C. Protein translocation into proteoliposomes in the absence of the proton motive force thus required SecG whereas that in cells, which always generate the proton motive force, did not.

【 授权许可】

Unknown