FUNCTIONAL-ANALYSIS OF THE BACILLUS-SUBTILIS PURT GENE ENCODING FORMATE-DEPENDENT GLYCINAMIDE RIBONUCLEOTIDE TRANSFORMYLASE

The purT gene from Bacillus subtilis encoding the formate-dependent gl ycinamide ribonucleotide transformylase T was cloned by functional com plementation of an Escherichia coil purN purT double mutant, The nucle otide sequence revealed an open reading frame of 384 amino acids. The purT amino acid sequence showed similarity to the enzyme phosphoribosy laminoimidazole carboxylase encoded by the purK gene but not to the N- 10-formyltetrahydrofolate-dependent glycinamide ribonucleotide transfo rmylase N enzyme encoded by the purN gene, The glycinamide ribonucleot ide transformylase T level was repressed in cells grown in rich medium compared to minimal-medium-grown cells. However, when the culture ent ered the stationary-growth phase the enzyme level increased in rich me dium and decreased in minimal medium, By comparing the deduced amino a cid sequence of the B. subtilis purT gene product with translated nucl eotide sequences in various databanks, evidence for the existence of p utative purT genes in the Cram-negative bacteria Pasteurella haemolyti ca and Pseudomonas aeruginosa was obtained.