Regulation of Purine Nucleotide Synthesis in Bacillus subtilis

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Abstract
The repressive effects of several purine derivatives on the formation of 5 enzymes involved in purine nucleotide biosynthesis in B. subtilis were analyzed. Formation of purine ribose pyrophosphate [PRPPJ amldotransferase, inosine monophosphate [IMP] transformylase, IMP dehydrogenase, soluble adenosine monophosphate [sAMP] synthetase and adenylosuccinate lyase was repressed by adenosine and guanosine. Inosine had no effect on these enzymes except on IMP transformylase, and xanthosine had no effect on all of these enzymes. L-Histine was without effect. The repressive effect of adenosine on the formation of the 5 tested enzymes was practically the same as that of guanosine. Guanosine monophosphate [GMP] was much more effective than guanosine and guanine. Based on the results of experiments of repression and derepression, the enzymes were classified into 3 groups according to their sensitivity to adenosine and guanosine: sAMP synthetase and adenylosuccinate lyase (group-A) were less sensitive than PRPP amidotransferase and IMP dehydrogenase (group-B). The IMP transformylase (group-C) was inactivated during cultivation in the presence of adenosine or guanosine.