The CTPase Nudix hydrolases from E. coli and M. tuberculosis, potential regulators of pyrimidine and lipid biosynthesis

Abstract

Orf135 from E. coli and Rv1160 from M. tuberculosis are CTPases and members of the Nudix hydrolase family that hydrolyze substrates containing a nucleoside diphosphate linked to some moiety, x, and are identified by the common signature sequence GX5EX7REUXEEXGU, where U = I, L, or V. Orf135 and Rv1160 have been cloned, expressed, purified, and characterized. CTP is the feedback inhibitor of pyrimidine biosynthesis and a precursor to lipid biosynthesis, thus Orf135 and Rv1160 may help regulate these pathways through degradation of CTP. There have been reports of Orf135 and Rv1160 as antimutators, however we have determined that neither enzyme complements the antimutator MutT. To definitively establish Orf135’s role in the cell, we are working with a knock-out mutant of Orf135 to determine its phenotype. To establish Rv1160’s role in the cell, we will do complementation studies. Determining the significance of these enzymes will help establish their potential as novel antibiotic targets. This research is currently supported by an NIH AREA grant.