Regulation of GMP reductase in Salmonella typhimurium

The levels of guanosine 5'-phosphate reductase (EC 1.6.6.8) in Salmonella typhimurium appear to be modulated by changes in the ratio of the adenine and guanine nucleotide pools. Alterations of this ratio may be induced by high levels of guanosine in the culture medium or by genetic lesions in one of several purine interconversion enzymes, such as pur A or pur B mutants. The induction of the reductase requires transcription and translation processes and, in contrast to earlier observation with Escherichia coli, is not dependent on cyclic adenosine 3',5'-phosphate or the cyclic adenosine 3',5'-phosphate receptor protein.