Effects of pre-protein overexpression on SecB synthesis in Escherichia coli.
Protein translocation through the cytoplasmic membrane of Escherichia coli involves cytosolic chaperones. The export-dedicated chaperone SecB mediates targeting of a subset of pre-proteins. In this report, synthesis of SecB in response to plasmid-mediated overexpression of pre-proteins was studied. Overexpression of SecB-dependent pre-proteins stimulated synthesis of SecB under conditions where the cellular export capacity was saturated or uncomplexed SecB was trapped. On the contrary, overexpression of SecB-independent pre-beta-lactamase reduced the promoter activity of secB. The results suggest that uncomplexed SecB can be sequestered by synthesis of SecB-dependent pre-proteins. Furthermore, these data demonstrate the distinct action of the SecB- and signal recognition particle-dependent protein targeting pathways.
Institute for Molecular Biology, Jena University, Germany. jmueller@imb-jena.de
J P
JP
Müller
D018528:ATP-Binding Cassette Transporters; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D018832:Molecular Chaperones / Q000378:metabolism; D009004:Monosaccharide Transport Proteins; D011498:Protein Precursors / Q000378:metabolism*; D001618:beta-Lactamases / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D018832:Molecular Chaperones; D009004:Monosaccharide Transport Proteins; D011498:Protein Precursors; C057842:SecB protein, Bacteria; C461599:maltose transport system, E coli; C057184:outer membrane protein A precursor (E coli); D001618:beta-Lactamases