Genetic and biochemical characterization of Salmonella enterica serovar typhi deoxyribokinase.

We identified in the genome of Salmonella enterica serovar Typhi the gene encoding deoxyribokinase, deoK. Two other genes, vicinal to deoK, were determined to encode the putative deoxyribose transporter (deoP) and a repressor protein (deoQ). This locus, located between the uhpA and ilvN genes, is absent in Escherichia coli.

The highly similar TMP kinases of Yersinia pestis and Escherichia coli differ markedly in their AZTMP phosphorylating activity.

Thymidine monophosphate (TMP) kinases are key enzymes in nucleotide synthesis for all living organisms. Although eukaryotic and viral TMP kinases have been studied extensively, little is known about their bacterial counterparts. To characterize the TMP kinase of Yersinia pestis, a chromosomal region encompassing its gene (tmk) was cloned and sequenced; a high degree of conservation with the corresponding region of Escherichia coli was found.

Substitution of an alanine residue for glycine 146 in TMP kinase from Escherichia coli is responsible for bacterial hypersensitivity to bromodeoxyuridine.

The wild-type TMP kinases from Escherichia coli and from a strain hypersensitive to 5-bromo-2'-deoxyuridine were characterized comparatively. The mutation at codon 146 causes the substitution of an alanine residue for glycine in the enzyme, which is accompanied by changes in the relative affinities for 5-Br-UMP and TMP compared to those of the wild-type TMP kinase. Plasmids carrying the wild-type tmk gene from Escherichia coli or Bacillus subtilis, but not the defective tmk gene, restored the resistance to bromodeoxyuridine of an E.