TY - JOUR
T1 - Chromosomal β-lactamase of Klebsiella oxytoca, a new class A enzyme that hydrolyzes broad-spectrum β-lactam antibiotics
AU - Arakawa, Y.
AU - Ohta, M.
AU - Kido, N.
AU - Mori, M.
AU - Ito, H.
AU - Komatsu, T.
AU - Fujii, Y.
AU - Kato, N.
PY - 1989
Y1 - 1989
N2 - The chromosomally encoded β-lactamase gene of Klebsiella oxytoca E23004, a strain resistant to cefoperazone and aztreonam, was cloned and expressed in Escherichia coli HB101. The molecular mass and pI of this enzyme were 28 kilodaltons and 7.4, respectively. Although the β-lactamase of K. oxytoca hydrolyzed many cephalosporins, including broad-spectrum drugs, the nucleotide sequence and deduced amino acid sequence lacked homology with chromosomal class C β-lactamase genes (ampC) of E. coli or Citrobacter freundii. Rather, about 45% nucleotide sequence homology and 40% deduced amino acid sequence homology were observed between the K. oxytoca β-lactamase and TEM-1, a class A β-lactamase which does not efficiently hydrolyze cephalosporins. Values of K(m), relative V(max), and relative V(max)/K(m) for the K. oxytoca β-lactamase indicated that the enzyme is a penicillinase but that it can hydrolyze cefoperazone effectively and other broad-spectrum cephems weakly. Hence, the chromosomal β-lactamase of K. oxytoca E23004 belongs to class A but differences in its amino acid sequence provide a broader spectrum of activity.
AB - The chromosomally encoded β-lactamase gene of Klebsiella oxytoca E23004, a strain resistant to cefoperazone and aztreonam, was cloned and expressed in Escherichia coli HB101. The molecular mass and pI of this enzyme were 28 kilodaltons and 7.4, respectively. Although the β-lactamase of K. oxytoca hydrolyzed many cephalosporins, including broad-spectrum drugs, the nucleotide sequence and deduced amino acid sequence lacked homology with chromosomal class C β-lactamase genes (ampC) of E. coli or Citrobacter freundii. Rather, about 45% nucleotide sequence homology and 40% deduced amino acid sequence homology were observed between the K. oxytoca β-lactamase and TEM-1, a class A β-lactamase which does not efficiently hydrolyze cephalosporins. Values of K(m), relative V(max), and relative V(max)/K(m) for the K. oxytoca β-lactamase indicated that the enzyme is a penicillinase but that it can hydrolyze cefoperazone effectively and other broad-spectrum cephems weakly. Hence, the chromosomal β-lactamase of K. oxytoca E23004 belongs to class A but differences in its amino acid sequence provide a broader spectrum of activity.
UR - http://www.scopus.com/inward/record.url?scp=0024579078&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0024579078&partnerID=8YFLogxK
U2 - 10.1128/AAC.33.1.63
DO - 10.1128/AAC.33.1.63
M3 - Article
C2 - 2653216
AN - SCOPUS:0024579078
SN - 0066-4804
VL - 33
SP - 63
EP - 70
JO - Antimicrobial agents and chemotherapy
JF - Antimicrobial agents and chemotherapy
IS - 1
ER -