Biochemical characterisation of the CTX-M-14 beta-lactamase.
Cefotaxime-resistant Escherichia coli TUM1121 was isolated from an abscess of an 83-year-old patient. The CTX-M-14 gene was located on a 70 kb plasmid. The enzyme was purified and its activity was analysed. CTX-M-14 was poorly active against ceftazidime and aztreonam. Aztreonam behaved as a competitive inhibitor. Among the tested suicide substrates for class A beta-lactamases, sulbactam was a rather good substrate. Tazobactam and clavulanic acid behaved as inactivators. The interactions between clavulanic acid and CTX-M-14 were characterised by progressive inactivation of the beta-lactamase. Carbapenems such as imipenem, meropenem or doripenem did not behave as inactivators of CTX-M-14, however very small k(cat) values were observed. This result shows that CTX-M-14 is able to hydrolyse carbapenems.
Ishii
Yoshikazu
Y
Centre for Protein Engineering, University of Liège, B6 Institute of Chemistry, Sart Tilman, B4000 Liège, Belgium. yoishii@med.toho-u.ac.jp
Galleni
Moreno
M
Ma
Ling
L
Frère
Jean-Marie
JM
Yamaguchi
Keizo
K
D003001:Cloning, Molecular; D007700:Kinetics; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
C456080:beta-lactamase CTX-M-14; D001618:beta-Lactamases