title: Competition between ribosome and SecA binding promotes Escherichia coli secA translational regulation.
abstract: SecA protein, the protein translocation ATPase of Escherichia coli, autogenously regulates its translation during normal protein secretion by binding to a secretion-responsive element located near the 5' end of its gene on geneX-secA mRNA. In order to characterize this autoregulation further, RNA footprinting and primerextension inhibition (toeprinting) studies were carried out with a segment of geneX-secA RNA, 30S ribosomal subunits and tRNAfMet along with purified SecA protein. The results show that ribosome and SecA-binding sites overlap, indicating that a simple competition for binding of geneX-secA mRNA presumably governs the translation initiation step. Further analysis showed that SecA protein was able to specifically dissociate a preformed 30S-tRNAfMet-geneX-secA RNA ternary complex as indicated by the disappearance of its characteristic toeprint after SecA addition. These findings are consistent with secA autoregulation, and they suggest a novel mechanism for the autoregulatory behavior of this complex protein.
authors.affiliation: Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, Connecticut 06459, USA.
authors.forename: R
authors.initials: R
authors.lastname: Salavati
authors.forename: D
authors.initials: D
authors.lastname: Oliver
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001667:Binding, Competitive; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D011485:Protein Binding; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012358:RNA, Transfer, Met / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012358:RNA, Transfer, Met; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins