James Ruble ACF Abstract FY10

Effects of Asn152 Mutation on Substrate Selectivity of P99 Cephalosporinase

Conference Name: Spring 2010/239th National Meeting of the American Chemical Society

For over 50 years, bacterial infection has been fought with beta-lactam antibiotics.  Bacteria, however, have evolved resistance to these compounds through beta-lactamase enzymes, which hydrolyze their beta-lactam rings and render them inactive.  Of major concern are bacteria that have become resistant through mutations in their beta-lactamase genes, altering the selectivity of enzyme substrate and allowing the mutant enzymes to hydrolyze many different beta-lactams.  For the enzyme P99 cephalosporinase it has been shown that mutation of a conserved asparagines residue at position 152 has a substantial effect on its substrate selectivity.  In this study, a kinetic characterization of the N152G mutant was performed with several compounds.  Attempts to crystallize the mutant are also underway.  Further studies will help elicit the structure and function relationship for this enzyme and might allow development of improved antibiotics.