title: SecA: the ubiquitous component of preprotein translocase in prokaryotes.
abstract: SecA is an obligatory component of the complex hetero-septameric translocase of prokaryotes. It is unique in that it exists as two forms within the holoenzyme; first, as a structural component of the preprotein channel and second, as an ATP-dependent membrane cycling factor facilitating the translocation of a broad class of proteins across the cytoplasmic membrane. While the translocase activity of SecA appears to be functionally conserved, it is not clear whether the mechanisms of regulation of the secA gene are similarly maintained. The recent characterization of an ATP-dependent RNA helicase activity of SecA offers a unique mechanism for SecA to communicate the secretion status of the cell to the appropriate regulatory circuits simply by the unwinding of an appropriate RNA target. Resolution of these two activities through combined biochemical, genetic, and biophysical studies should lead to a better understanding of the role of SecA in bacterial secretion.
authors.affiliation: Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC 29425-2230, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Schmidt
authors.forename: K B
authors.initials: KB
authors.lastname: Kiser
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D008954:Models, Biological; D011498:Protein Precursors / Q000378:metabolism*; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D011498:Protein Precursors; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins