Open AccessThe TEM‐3 β‐lactamase, which hydrolyzes broad‐spectrum cephalosporins, is derived from the TEM‐2 penicillinase by two amino acid substitutions
Author(s) -
Sougakoff Wladimir,
Goussard Sylvie,
Courvalin Patrice
Publication year - 1988
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1988.tb03204.x
Subject(s) - cephalosporin , substrate (aquarium) , amino acid , amino acid substitution , plasmid , enzyme , chemistry , peptide sequence , hydrolysis , mutation , biochemistry , stereochemistry , biology , gene , antibiotics , ecology
We have determined the nucleotide sequence of the blaT ‐3 gene of plasmid pCF04 which confers resistance to penicillins and most cephalosporins by mediating the production of TEM‐3 β‐lactamase. The deduced amino acid sequence of TEM‐3 differed in two positions from that of the TEM‐2 penicillinase: Lys (TEM‐3) for Glu (TEM‐2) at position 102, and Ser (TEM‐3) for Gly (TEM‐2) at position 236 of the unprocessed protein. Examination of the location of the two modified amino acids of TEM‐3 in the tertiary structure of class A β‐lactamases suggested that they both are part of the substrate binding site. Analysis, by in vitro recombination, indicated that each mutation contributes to the extented substrate range of the enzyme, compared to that of the TEM‐type penicillinase, and that the strength of the promoter of blaT ‐3 is responsible for high‐level resistance towards broad‐spectrum cephalosporins of strains producing TEM‐3.