How posttranslational modification of nitrogenase is circumvented in Rhodopseudomonas palustris strains that produce hydrogen gas constitutively.

ABSTRACT: Nitrogenase catalyzes the conversion of dinitrogen gas (N(2)) and protons to ammonia and hydrogen gas (H(2)). This is a catalytically difficult reaction that requires large amounts of ATP and reducing power. Thus, nitrogenase is not normally expressed or active in bacteria grown with a readily utilized nitrogen source like ammonium. nifA* mutants of the purple nonsulfur phototrophic bacterium Rhodopseudomonas palustris have been described that express nitrogenase genes constitutively and produce H(2) when grown with ammonium as a nitrogen source. This raised the regulatory paradox of why these mutants are apparently resistant to a known posttranslational modification system that should switch off the activity of nitrogenase. Microarray, mutation analysis, and gene expression studies showed

SUBMITTER: Heiniger EK 

PROVIDER: S-EPMC3273035 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature