Grant: CIHR Fellowship

Beta-lactam antibiotics are invaluable in the battle against pathogenic bacterial infection and remain most widely used. This powerful group of antibiotics acts to destroy the integrity of bacterial cell-walls, leaving bacteria highly vulnerable to cell lysis and death. Certain bacteria nevertheless have developed resistance mechanisms that block beta-lactam action, rendering them useless. A notable example is the "superbug" Methicillin-Resistant Staphylococcus Aureus (MRSA) which is resistant to all classes of beta-lactam antibiotics, including the commonly prescribed penicillins and cephalosporins. Of particular concern is the rapid emergence of "community-acquired" MRSA affecting previously healthy individuals outside the healthcare setting, presenting an urgent world-wide health threat. The environmental sensing of beta-lactams is key to the antibiotic resistance mechanism of MRSA and is mediated by sensor-transducer proteins BlaR1 and MecR1. Upon detection of beta-lactams in the milieu, these proteins trigger a signaling pathway resulting in the production of enzymes that allow bacteria to both destroy and ignore the antibiotic and thereby avert cell-death. Understanding the structure and mechanism of these beta-lactam sensing proteins would greatly benefit rational structure-based drug design aimed at bacterial re-sensitization to present antibiotics as well as novel antibiotic development. Structural investigation of BlaR1/MecR1 which demands large amounts of protein has been notoriously challenging with conventional cell-based expression. Alternately, here we employ a customized "cell-free" protein synthesis system to allow overexpression of BlaR1/MecR1, facilitating crystallographic and NMR structural studies. In partnership with the Centre for Drug Research and Discovery at UBC, the acquired structural and mechanistic data will be used to screen and optimize novel lead inhibitors against BlaR1/MecR1 induced antibiotic resistance in the MRSA superbug.