The F286Y mutation of PrlA4 tempers the signal sequence suppressor phenotype by reducing the SecA binding affinity

FEBS Letters

Swaving, Jelto¹  van der Does, Chris¹  de Keyzer, Jeanine¹  Driessen, Arnold J.M.¹ 

[1]Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands

关键词: Protein translocation;    SecA;    SecY;    Signal sequence suppression;   

DOI  :  10.1016/S0014-5793(01)03213-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

SecYEG forms the protein-conducting channel of the Escherichia coli translocase. It binds the peripheral ATPase SecA that drives the preprotein translocation reaction. PrlA4 is a double mutant of SecY that enables the translocation of preproteins with a defective or even missing signal sequence. The effect of the individual mutations, F286Y and I408N, was studied with SecYEG proteoliposomes. SecY(I408N) is responsible for the increased translocation of preproteins with a defective and normal signal sequence, and exhibits a stronger prl phenotype than PrlA4. This activity correlates with an elevated SecA-translocation ATPase and SecA binding affinity. SecY(F286Y) supports only a low SecA binding affinity, preprotein translocation and SecA translocation ATPase activity. These results suggest that the second site F286Y mutation reduces the strength of the I408N mutation of PrlA4 by lowering the SecA binding affinity.

【 授权许可】

Unknown