Direct sequencing of the amplified structural gene and promoter for the extended-broad-spectrum beta-lactamase TEM-9 (RHH-1) of Klebsiella pneumoniae.
Extended-broad-spectrum beta-lactamase TEM-9, detected in a clinical isolate of Klebsiella pneumoniae, confers high-level resistance to recent cephalosporins, in particular ceftazidime, and to the monobactam aztreonam. Using oligonucleotide probes, we found that the plasmid gene blaT-9 encoding TEM-9 differs from characterized blaT genes by a new combination of already known mutations. Gene blaT-9 was further studied by direct sequencing of an amplified 1.1-kb DNA fragment which contained the open reading frame and its promoter. Analysis of the nucleotide and of the deduced amino acid sequence confirmed the hybridization results and indicated that TEM-9 differs from TEM-1 by four amino acid substitutions: Phe at position 19 and Met at position 261, which have been found in TEM-4 and are known not to expand the enzyme substrate range; Lys 102, detected in TEM-3 and TEM-4, and Ser 162, present in TEM-5 and TEM-7. Each of the latter substitutions enlarges the substrate spectrum of the enzymes and they are found associated for the first time in TEM-9.
Mabilat
C
C
CNRS U.A. 271, Institut Pasteur, Paris, France.
Goussard
S
S
Sougakoff
W
W
Spencer
R C
RC
Courvalin
P
P
D000596:Amino Acids; D001483:Base Sequence; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D007711:Klebsiella pneumoniae / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D001618:beta-Lactamases / Q000235:genetics*
D000596:Amino Acids; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; C064468:beta-lactamase TEM-9; D001618:beta-Lactamases