Open AccessRequirements for translocation of periplasmic domains in polytopic membrane proteins
Author(s) -
Kerstin Uhland,
Rainer Ehrle,
Thomas Zander,
Michael Ehrmann
Publication year - 1994
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.176.15.4565-4571.1994
Subject(s) - periplasmic space , biology , alkaline phosphatase , transmembrane domain , complementation , mutant , biochemistry , transmembrane protein , phosphatase , cytoplasm , membrane protein , microbiology and biotechnology , amino acid , membrane , enzyme , gene , escherichia coli , receptor
Periplasmic domains of cytoplasmic membrane proteins require export signals for proper translocation. These signals were studied by using a MalF-alkaline phosphatase fusion in a genetic selection that allowed the isolation of mislocalization mutants. In the original construct, alkaline phosphatase is fused to the second periplasmic domain of the membrane protein, and its activity is thus confined exclusively to the periplasm. Mutants that no longer translocated alkaline phosphatase were selected by complementation of a serB mutation. A total of 11 deletions in the amino terminus were isolated, all of which spanned at least the third transmembrane segment. This domain immediately precedes the periplasmic domain to which alkaline phosphatase was fused. Our results obtained in vivo support the model that amino-terminal membrane-spanning segments are required for translocation of large periplasmic domains. In addition, we found that the inability to export the alkaline phosphatase domain could be suppressed by a mutation, prlA4, in the secretion apparatus.