A mutation in the putative CRP binding site of the promoter of serovar Typhimurium enables growth with low orotate concentrations.

and use the inner membrane transporter DctA to import the pyrimidine biosynthetic pathway intermediate orotate from the environment. To study the regulation of expression, we used an serovar Typhimurium pyrimidine auxotroph to select a mutant that could grow in an otherwise nonpermissive culture medium containing glucose and a low concentration of orotate. Whole genome sequencing revealed a point mutation upstream of in the putative cyclic AMP receptor protein (CRP) binding site.