The Role of Histone H3K79 Methylation Patterns in UV-Induced Sister Chromatid Exchange and G1/S Checkpoint Response in Saccharomyces cerevisiae

Indianapolis, IN

Tuberculosis is one of the words deadliest diseases with over 2.5-3 million deaths per year. The causative agent of tuberculosis, Mycobacterium tuberculosis, is especially difficult to treat. M. tuberculosis acquires energy during dormant infection by degrading host cell lipids for energy, making enzymes involved in lipid metabolism promising drug targets for treating TB. Amongst lipid metabolizing enzymes are 30 different lipases of which the majority are currently uncharacterized. To determine potential inhibitors for TB lipases, we are characterizing the enzymatic activity and substrate specificity of LipW, one of the 30 TB lipases. To do this, we measured the enzymatic activity of two mycobacterial LipW homologues against a library of fluorogenic enzyme substrates. LipW showed bell curve specificity for substrates with two carbons as opposed to other length chains. Homolog LipW-Marinum was found to prefer substrates with shorter carbon chains (Kcat/Km=1227) in contrast to those with longer carbon chains (Kcat/Km=86). Its homolog LipW-Smegmatis showed a similar trend with substrates ranging from 1 to 3 carbons. We are now working to determine the structural features that control the narrow substrate specificity of LipW.