ampC cephalosporinase of Escherichia coli K-12 has a different evolutionary origin from that of beta-lactamases of the penicillinase type.
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Jaurin B, Grundstrom T
ampC cephalosporinase of Escherichia coli K-12 has a different evolutionary origin from that of beta-lactamases of the penicillinase type.
Proc Natl Acad Sci U S A. 1981 Aug;78(8):4897-901.
- PubMed ID
- 6795623 [ View in PubMed]
- Abstract
A 1536-nucleotide-long sequence that carries the ampC beta-lactamase gene of the Escherichia coli K-12 chromosome has been determined. This gene codes for a protein of 377 amino acids, of which the first 19 amino acids form a signal peptide. The molecular weight of the mature enzyme was determined to be 39,600. The ampC beta-lactamase with a substrate specificity for cephalosporins showed no significant sequence homologies with beta-lactamases of the penicillinase type or with D-alanine carboxypeptidases. However, because the region around serine-80 of the ampC beta-lactamase has extensive homology with an active-site fragment of the Pseudomonas aeruginosa cephalosporinase, we suggest that the ampC cephalosporinase as well as related cephalosporinases form a distinct group of serine beta-lactamases that have an evolutionary origin different from that of the serine penicillinases and thus constitute a new class of beta-lactamases.