The mature portion of Escherichia coli maltose-binding protein (MBP) determines the dependence of MBP on SecB for export.

AUTOR(ES)

Gannon, P M

RESUMO

The product of the secB gene is required for export of a subset of secreted proteins to the outer membrane and periplasm of Escherichia coli. Precursor maltose-binding protein (MBP) accumulates in the cytoplasm of secB-carrying mutants, but export of alkaline phosphatase is only minimally affected by secB mutations. When export of MBP-alkaline phosphatase hybrid proteins was analyzed in wild-type and secB-carrying mutant strains, the first third of mature MBP was sufficient to render export of the hybrid proteins dependent on SecB. Substitution of a signal sequence from a SecB-independent protein had no effect on SecB-dependent export. These findings show that the first third of mature MBP is capable of conferring export incompetence on an otherwise competent protein.

Documentos Relacionados

• SecB-independent export of Escherichia coli ribose-binding protein (RBP): some comparisons with export of maltose-binding protein (MBP) and studies with RBP-MBP hybrid proteins.
• prlA suppression of defective export of maltose-binding protein in secB mutants of Escherichia coli.
• Mutations that improve export of maltose-binding protein in SecB- cells of Escherichia coli.
• Escherichia coli sec mutants accumulate a processed immature form of maltose-binding protein (MBP), a late-phase intermediate in MBP export.
• Expression of Escherichia coli SecB in Bacillus subtilis facilitates secretion of the SecB-dependent maltose-binding protein of E. coli.