| Abstrakt: |
ABSTRACTFrom genomic DNA of the clinical isolate Nocardia farcinicaVIC, a 1.6-kb Sau3AI fragment was cloned and expressed in Escherichia coliJM109. The recombinant strain expressed a β-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 β-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 β-lactamases, being most closely related to PEN-A fromBurkholderia cepacia(52%). AblaFAR-1-like gene was found in all studiedN. farcinicastrains, underlining the constitutive origin of this gene. |
