Structure–function relationships of UMP kinases from pyrH mutants of Gram-negative bacteria

Abstract

Bacterial uridine monophosphate (UMP) kinases are essential enzymes encoded bypyrHgenes, and conditional-lethal or otherpyrHmutants were analysed with respect to structure–function relationships. A set of thermosensitivepyrHmutants fromEscherichia coliwas generated and studied, along with already describedpyrHmutants fromSalmonella entericaserovar Typhimurium. It is shown that Arg-11 and Gly-232 are key residues for thermodynamic stability of the enzyme, and that Asp-201 is important for both catalysis and allosteric regulation. A comparison of the amino acid sequence of UMP kinases from several prokaryotes showed that these were conserved residues. Discussion on the enzyme activity level in relation to bacterial viability is also presented.