Antibiotics have been essential to the development of modern medical practices and are often used as the first line of defense in most illnesses. However, a cause of increasing problems and concerns in the medical community is the development of antibiotic-resistance mechanisms in pathogenic bacteria. Some of the most worrying enzymes to emerge are metallo-beta-lactamases (MBLs) – specifically, New Delhi (NDM), Verona Integron-Encoded (VIM), and active-on-imipenem (IMP) metallo-Beta-Lactamases – that are able to hydrolyze antibiotics that harbor beta-lactam rings, thus deactivating these frequently prescribed medicines. The genes that encode for these enzymes are also capable of horizontal transfer, making the spread of antibiotic resistant bacteria a global threat. The goal of this project is to elucidate structures of these metallo-beta-lactamases both in isolation and in complex with small molecule inhibitors in order to find specific and potent metallo-beta-lactamase inhibitors, allowing restoration of activity to beta-lactam antibiotics. Three mutations of both VIM (2, 20, and 31) and NDM (1, 4, 12, and later, X) metallo-beta-lactamases were chosen for crystallographic studies due to their propensity to crystallize with inhibitory molecules bound in their active sites, and due to their ability to withstand a large variety and concentration of antibiotics in and out of the presence of zinc. Due to interest in these enzymes’ ability to function even in low concentrations of zinc, a variant of New Delhi Metallo-beta-lactamase was constructed, a mono-zinc mutant (NDMX) that may provide insight on the mechanisms of these proteins preceding the execution of their hydrolyzing mechanisms.
Authors: Matthew Morris & Matthew Orischak
Faculty Advisor: Dr. Rick Page, Department of Chemistry & Biochemistry
Graduate Student Advisor: Ben Shurina, Department of Chemistry & Biochemistry
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