Sequences of homologous beta-lactamases from clinical isolates of Serratia marcescens with different substrate specificities.
Genes for two group 1 beta-lactamases, SRT-1 and SST-1, were sequenced. These beta-lactamases were produced by clinical isolates of Serratia marcescens, isolates GN16694 and GN19450, respectively. The resulting enzymes were 96% identical. SRT-1 hydrolyzed oxyimino cephalosporins, but SST-1 hardly hydrolyzed them. At residue 213 in the third motif, which is conserved among group 1 beta-lactamases, SRT-1 and SST-1 had Lys and Glu, respectively. By site-directed mutagenesis, the substitution of Glu by Lys at residue 213 in SST-1 resulted in an enzyme that hydrolyzed oxyimino cephalosporins.
Matsumura
N
N
Episome Institute, Seta-gun Gunma, Japan.
Minami
S
S
Mitsuhashi
S
S
D000595:Amino Acid Sequence; D002511:Cephalosporins / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012706:Serratia marcescens / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism*
D002511:Cephalosporins; D001618:beta-Lactamases