Export and trimerization pathways of maltoporin overlap in the inner membrane of Escherichia coli.
The production of functional porins involves multiple steps including: export of precursor polypeptides from the cytoplasm, assembly of monomers into trimers, and stabilization of trimers by association with lipopolysaccharide. In this report, a late export/assembly intermediate of the maltoporin (LamB) is found in the inner membrane of Escherichia coli using cell fractionation studies. This processed intermediate is transiently associated with a unique Triton X-100-insoluble subfraction of the inner membrane. The kinetics of appearance and solubility characteristics of this intermediate correspond to those of the metastable trimer form of LamB, suggesting that the export and assembly pathways overlap in the inner membrane prior to final localization in the bulk outer membrane.
Stader
J
J
School of Biological Sciences, University of Missouri-Kansas City 64110-2499.
Justice
S
S
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002458:Cell Fractionation / Q000379:methods; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006358:Hot Temperature; D018272:Porins; D011233:Precipitin Tests; D011487:Protein Conformation; D011489:Protein Denaturation; D021382:Protein Sorting Signals; D011991:Receptors, Virus / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility; D001616:beta-Galactosidase
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C085044:LamB signal peptide, E coli; D018272:Porins; D021382:Protein Sorting Signals; D011991:Receptors, Virus; D011993:Recombinant Fusion Proteins; C016532:maltoporins; D001616:beta-Galactosidase