Interaction of the Motor Protein SecA and the Bacterial Protein Translocation Channel SecYEG in the Absence of ATP

Abstract

16Translocation of many secretory proteins through the bacterial plasma membrane is facilitated by 17 a complex of the protein translocase SecYEG with the motor protein SecA. The ATP-free complex 18 is unstable in detergent, raising the question how SecA may perform several rounds of ATP 19 hydrolysis without being released. Here we show that dual recognition of (i) SecYEG and (ii) acidic 20 lipids in its immediate vicinity confers an apparent nanomolar affinity. As a result the complex 21 between SecA and reconstituted SecYEG may be stable for tens of seconds as visualized by high-22 27 28 29 30