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SecG plays a critical role in protein translocation in the absence of the proton motive force as well as at low temperature
Author(s) -
Hanada Mitsuharu,
Nishiyama Ken-ichi,
Tokuda Hajime
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00066-x
Subject(s) - chromosomal translocation , chemiosmosis , proton , biophysics , chemistry , translocase , membrane , biology , biochemistry , physics , gene , atp synthase , quantum mechanics
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.