Differential responses of Escherichia coli cells expressing cytoplasmic domain mutants of penicillin-binding protein 1b after impairment of penicillin-binding proteins 1a and 3.
Penicillin-binding protein 1b (PBP1b) is the major high-molecular-weight PBP in Escherichia coli. Although it is coded by a single gene, it is usually found as a mixture of three isoforms which vary with regard to the length of their N-terminal cytoplasmic tail. We show here that although the cytoplasmic tail seems to play no role in the dimerization of PBP1b, as was originally suspected, only the full-length protein is able to protect the cells against lysis when both PBP1a and PBP3 are inhibited by antibiotics. This suggests a specific role for the full-length PBP1b in the multienzyme peptidoglycan-synthesizing complex that cannot be fulfilled by either PBP1a or the shorter PBP1b proteins. Moreover, we have shown by alanine-stretch-scanning mutagenesis that (i) residues R(11) to G(13) are major determinants for correct translocation and folding of PBP1b and that (ii) the specific interactions involving the full-length PBP1b can be ascribed to the first six residues at the N-terminal end of the cytoplasmic domain. These results are discussed in terms of the interactions with other components of the murein-synthesizing complex.
Chalut
C
C
Institut de Pharmacologie et de Biologie Structurale, UMR 5089 du CNRS, Toulouse, France.
Charpentier
X
X
Remy
M H
MH
Masson
J M
JM
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001398:Aztreonam / Q000494:pharmacology; D001426:Bacterial Proteins; D002352:Carrier Proteins; D002509:Cephaloridine / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology; D003593:Cytoplasm / Q000201:enzymology*; D019281:Dimerization; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins; D006602:Hexosyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002267:Muramoylpentapeptide Carboxypeptidase; D009154:Mutation; D046915:Penicillin-Binding Proteins; D046928:Peptidoglycan Glycosyltransferase; D010458:Peptidyl Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D002511:Cephalosporins; D029968:Escherichia coli Proteins; D007527:Isoenzymes; D009097:Multienzyme Complexes; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D046928:Peptidoglycan Glycosyltransferase; C478681:penicillin-binding protein 1B, E coli; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase; D002267:Muramoylpentapeptide Carboxypeptidase; D001398:Aztreonam; D002509:Cephaloridine