RT Journal Article
SR Electronic
T1 Interaction of the Motor Protein SecA and the Bacterial Protein Translocation Channel SecYEG in the Absence of ATP
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 799247
DO 10.1101/799247
A1 Klemens Winkler
A1 Andreas Karner
A1 Andreas Horner
A1 Christof Hannesschlaeger
A1 Denis Knyazev
A1 Christine Siligan
A1 Mirjam Zimmermann
A1 Roland Kuttner
A1 Peter Pohl
A1 Johannes Preiner
YR 2020
UL http://biorxiv.org/content/early/2020/03/27/799247.abstract
AB Translocation of many secretory proteins through the bacterial plasma membrane is facilitated by a complex of the SecYEG channel with the motor protein SecA. The ATP-free complex is unstable in detergent, raising the question how SecA may perform several rounds of ATP hydrolysis without being released from the membrane embedded SecYEG. Here we show that dual recognition of (i) SecYEG and (ii) vicinal acidic lipids confers an apparent nanomolar affinity. High-speed atomic force microscopy visualizes the complexes between monomeric SecA and SecYEG as being stable for tens of seconds. These long-lasting events and complementary shorter ones both give rise to single ion channel openings of equal duration. Furthermore, luminescence resonance energy transfer reveals two conformations of the SecYEG-SecA complex that differ in the protrusion depth of SecA’s two-helix finger into SecYEG’s aqueous channel. Such movement of the finger is in line with the power stroke mechanism of protein translocation.