Molecular cloning of the pyrE gene from the extreme thermophile Thermus flavus.

Mutants of the extreme thermophile Thermus flavus in the pyrimidine biosynthetic pathway (Pyr-) were isolated by resistance to 5-fluoroorotic acid. The pyrE gene, which codes for the orotate phosphoribosyltransferase, was cloned by recombination with one of the isolated Pyr- T. flavus mutant strains. It was subcloned by complementation of an Escherichia coli pyrE mutant strain and was sequenced. The deduced polypeptide sequence extends over 183 amino acids. Several independent Pyr- mutations were mapped within the pyrE locus by recombination with fragments of the cloned gene.