Biochemical-genetic analysis and distribution of FAR-1, a class A beta-lactamase from Nocardia farcinica.
From genomic DNA of the clinical isolate Nocardia farcinica VIC, a 1. 6-kb Sau3AI fragment was cloned and expressed in Escherichia coli JM109. The recombinant strain expressed a beta-lactamase (pI, 4.6), FAR-1, which conferred high levels of resistance to amoxicillin, piperacillin, ticarcillin, and cephalothin. The hydrolysis constants (kcat, Km, Ki, and 50% inhibitory concentration) confirmed the MIC results and showed that FAR-1 activity is inhibited by clavulanic acid and at a low level by tazobactam and sulbactam. Moreover, FAR-1 beta-lactamase hydrolyzes aztreonam (at a low level) without significant activity against ceftazidime, cefotaxime and imipenem. FAR-1 mature protein of molecular mass ca 32 kDa, has less than 60% amino acid identity with any other class A beta-lactamases, being most closely related to PEN-A from Burkholderia cepacia (52%). A blaFAR-1-like gene was found in all studied N. farcinica strains, underlining the constitutive origin of this gene.
Laurent
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F
Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique-Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 Le Kremlin-Bicêtre Cédex, France.
Poirel
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L
Naas
T
T
Chaibi
E B
EB
Labia
R
R
Boiron
P
P
Nordmann
P
P
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D009615:Nocardia / Q000201:enzymology*; D001618:beta-Lactamases / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D047090:beta-Lactams
D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases