Sequences of the active-site peptides of three of the high-Mr penicillin-binding proteins of Escherichia coli K-12.
The amino acid compositions of the radioactive peptides obtained from trypsin digestion of [14C]benzylpenicillin-labeled penicillin-binding proteins (PBPs) 1A, 1B, and 3 of Escherichia coli have been obtained. Complete digestion of these peptides with a combination of aminopeptidase M and carboxypeptidase Y showed that benzylpenicillin was bound to a serine residue in each of these proteins. Comparison of the compositions of the penicillin-labeled peptides with the complete amino acid sequences of PBPs 1A, 1B, and 3 showed that the acylated serine occurs near the middle of each of the proteins, within the conserved sequence Gly-Ser-Xaa-Xaa-Lys-Pro. The sequence around the acylated serine of these high Mr PBPs shows little similarity to that around the acylated serine of the low-Mr PBPs (D-alanine carboxypeptidases) or of the class A or class C beta-lactamases, except that in all of these enzymes which interact with penicillin the acylated serine residue occurs within the sequence Ser-Xaa-Xaa-Lys.
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001665:Binding Sites; D002268:Carboxypeptidases / Q000032:analysis*; D002352:Carrier Proteins / Q000032:analysis*; D004926:Escherichia coli / Q000032:analysis*; D006602:Hexosyltransferases; D008970:Molecular Weight; D002267:Muramoylpentapeptide Carboxypeptidase / Q000032:analysis*; D010400:Penicillin G / Q000378:metabolism; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D012694:Serine / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D012694:Serine; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002268:Carboxypeptidases; D002267:Muramoylpentapeptide Carboxypeptidase; D010400:Penicillin G