Replacement by site-saturation mutagenesis of residue 119 in NDM-1 metallo-{beta}-lactamase: a kinetic study [PublishAheadOfPrint]

NDM-1 is a subclass B1 metallo-β-lactamase which exhibits a broad activity spectrum against β-lactam antibiotics. In this study we report the kinetic study of six Q119X variants obtained by site-directed mutagenesis on NDM-1. All Q119X variants were able to hydrolyze very efficiently carbapenems, penicillins and 1^st, 2^nd, 3^rd and 4^th generation cephalosporins. In particular, Q119E, Q119Y, Q119V and Q119K mutants showed an improvement of k_cat/K_m towards penicillins respect to NDM-1. The catalytic efficiency of Q119K variant is about 65- and 70-fold higher than that of NDM-1 for benzylpenicillin and carbenicillin, respectively. The Q119K and Q119Y enzymes have k_cat/K_m values for ceftazidime of about 25- and 89-fold higher than NDM-1.

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