A mutation in the essential gene gmk (encoding guanlyate kinase) generates a requirement for adenine at low temperature in Salmonella enterica.
In Salmonella enterica serovar Typhimurium, gmk encodes guanylate kinase, an essential enzyme involved in the synthesis and salvage of guanine nucleotides. Here we report the isolation of a mutation in gmk that results in a nutritional requirement for adenine at low temperature. Comparisons of kinetic parameters from the wild-type and mutant Gmk enzymes revealed that the mutant enzyme had a more than 20-fold-higher Km for ATP than the wild-type enzyme. The growth dependence of the mutant on temperature and/or adenine could not be explained as a direct result of this kinetic difference. We propose a model in which previously described regulatory effects of GMP are responsible for these phenotypes.
Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Brian J
BJ
Beck
Mike
M
Huelsmeyer
Scott
S
Paul
D M
DM
Downs
D000225:Adenine / Q000378:metabolism*; D003080:Cold Temperature; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D020043:Genes, Essential; D051528:Guanylate Kinases; D007700:Kinetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D009703:Nucleoside-Phosphate Kinase / Q000235:genetics* / Q000378:metabolism; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D017422:Sequence Analysis, DNA
D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases; D000225:Adenine