title: SecA, a remarkable nanomachine.
abstract: Biological cells harbor a variety of molecular machines that carry out mechanical work at the nanoscale. One of these nanomachines is the bacterial motor protein SecA which translocates secretory proteins through the protein-conducting membrane channel SecYEG. SecA converts chemically stored energy in the form of ATP into a mechanical force to drive polypeptide transport through SecYEG and across the cytoplasmic membrane. In order to accommodate a translocating polypeptide chain and to release transmembrane segments of membrane proteins into the lipid bilayer, SecYEG needs to open its central channel and the lateral gate. Recent crystal structures provide a detailed insight into the rearrangements required for channel opening. Here, we review our current understanding of the mode of operation of the SecA motor protein in concert with the dynamic SecYEG channel. We conclude with a new model for SecA-mediated protein translocation that unifies previous conflicting data.
authors.affiliation: Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, Groningen, The Netherlands. i.kusters@rug.nl
authors.forename: Ilja
authors.initials: I
authors.lastname: Kusters
authors.forename: Arnold J M
authors.initials: AJ
authors.lastname: Driessen
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D020409:Molecular Motor Proteins; D021381:Protein Transport; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D020409:Molecular Motor Proteins; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins