ИСТИНА

Antibiotic resistance of bacterial pathogens - one of the major health care problems in the world. In recent years this problem has become even more threatening to the prevalence of panresistent microorganisms. The main mechanism of the resistance in Gram-negative bacteria results from the synthesis of bacterial enzymes - beta-lactamases (E.C. 3.5.2.6.), that destroy the antibiotic structure. To solve it, promising approaches involve the development of new antibacterial drugs, including inhibitors which can be active against a wide range of different beta-lactamases. Metallo-beta-lactamases belong to the class B and have in their active site one or two zinc ions involved in the catalysis. Metallo-beta-lactamases hydrolyze almost all groups of beta-lactam antibiotics; they are also resistant to the clinically used known inhibitors of class A beta-lactamases: e.g., sulbactam, tazobactam, and clavulanic acid. In 2009 in Klebsiella pneumoniae, it was found new metallo-beta-lactamase NDM-1, with high catalytic activity and the ability to hydrolyze nearly all beta-lactam antibiotics. To date, it is already described 16 variants of this enzyme, isolated in various geographic regions of the world [1]. A gene expression system has been designed to express the NDM-1 metallo-beta-lactamase gene in E. coli cells [2]. This system enables the synthesis of the recombinant protein in a soluble and active form. A method for the isolation and purification of the recombinant enzyme has been developed. The yield of the homogeneous protein preparation was 10–15 mg per liter of E.coli culture medium. The catalytic parameters of the recombinant NDM-1 beta-lactamase were measured for ampicillin (Km = 185 μM and kcat = 585 s–1) and meropenem (Km = 85 μM and kcat = 160 s–1). These values correlate well with the literature data. The catalytic parameters for the chromogenic CENTA substrate (Km = 14 μM and kcat = 290 s–1) were obtained for the first time. We have found a new innovative drug-candidate (AM 2015-1), exhibiting inhibition activity against NDM-1 metallo-beta-lactamase. The compound displays competitive inhibition of recombinant NDM-1 enzyme in the presence of meropenem with Ki (16.8+0.7 μM) and CENTA with Ki (12.5+0.5 μM) being 2-20 times better than those described in the literature for carbapenemases. Disk diffusion method demonstrated that the width of the lawn of bacterial growth inhibition zones of NDM-1 carbapenemase producing strains (409 and 410 K.pneumoniae) by meropenem and imipenem increases significantly in the presence of AM 2015-1. It was noted "broadening" the zone of growth inhibition in the region of overlap of diffusion fronts of carbapenem and AM 2015-1 compound, typical for enzyme inhibition. Similar effect was observed against metallo-beta-lactamase VIM-2 and serine carbapenemase OXA-48 producing strains. The method of microdilution in microtiter plate format shows that minimal inhibitory concentration of meropenem and imipenem for K.pneumoniae strains, producing carbapenemases in the presence of AM 2015-1 compound (2M) was reduced by 4 times, which is comparable to the inhibitory effect of EDTA at a concentration of 0.5 M. This work was supported by the Russian Foundation for Basic Research, project N 15-54-74007.