SEQUENCE-ANALYSIS OF 2 CHROMOSOMALLY MEDIATED INDUCIBLE BETA-LACTAMASES FROM AEROMONAS-SOBRIA, STRAIN 163A, ONE A-CLASS-D-PENICILLINASE, THE OTHER AN AMPC CEPHALOSPORINASE

Two beta-lactamase genes from Aeromonas sobria, strain 163a, have been cloned and sequenced, one encoding a typical class C cephalosporinase , designated CepS, the other a class D penicillinase, designated AmpS. CepS is predicted to be a mature protein of 38 kDa with a pI value of 7 . 0. The amino acid sequence of CepS is most similar to that of Amp C from Pseudomonas aeruginosa (54 . 7%). AmpS is predicted to be a mat ure protein of 27 kDa with a pI value of 7 . 9 that mostly closely res embles BLAD from Klebsiella pneumoniae (42 . 2%), and OXA-1 from Esche richia coli (36 . 6%), beta-lactamases that are encoded by genes carri ed on multiresistant transposons. AmpS differs significantly from the other class D beta-lactamases in that it hydrolyses cloxacillin poorly and is inducible. Both genes exhibit a high overall GC content and po ssess a high NNC and NNG codon preference, similar to that of genes fr om Pseudomonas spp.