Role of adenine deaminase in purine salvage and nitrogen metabolism and characterization of the ade gene in Bacillus subtilis

Abstract

The isolation of mutants defective in adenine metabolism in Bacillus subtilis has provided a tool that has made it possible to investigate the role of adenine deaminase in adenine metabolism in growing cells. Adenine deaminase is the only enzyme that can deaminate adenine compounds in B. subtilis, a reaction which is important for adenine utilization as a purine and also as a nitrogen source. The uptake of adenine is strictly coupled to its further metabolism. Salvaging of adenine is inhibited by the stringent response to amino acid starvation, while the deamination of adenine is not. The level of adenine deaminase was reduced when exogenous guanosine served as the purine source and when glutamine served as the nitrogen source. The enzyme level was essentially the same whether ammonia or purines served as the nitrogen source. Reduced levels were seen on poor carbon sources. The ade gene was cloned, and the nucleotide sequence and mRNA analyses revealed a single-gene operon encoding a 65-kDa protein. By transductional crosses, we have located the ade gene to 130 degrees on the chromosomal map.