Respiratory membrane endo-hydrogenase activity in the microaerophile Azorhizobium caulinodans is bidirectional.

ABSTRACT:

Background

The microaerophilic bacterium Azorhizobium caulinodans, when fixing N(2) both in pure cultures held at 20 µM dissolved O(2) tension and as endosymbiont of Sesbania rostrata legume nodules, employs a novel, respiratory-membrane endo-hydrogenase to oxidize and recycle endogenous H(2) produced by soluble Mo-dinitrogenase activity at the expense of O(2).

Methods and findings

From a bioinformatic analysis, this endo-hydrogenase is a core (6 subunit) version of (14 subunit) NADH:ubiquinone oxidoreductase (respiratory complex I). In pure A. caulinodans liquid cultures, when O(2) levels are lowered to <1 µM dissolved O(2) tension (true microaerobic physiology), in vivo endo-hydrogenase activity reverses and continuously evolves H(2) at high rates. In essence, H(+) ions th

SUBMITTER: Sprecher BN 

PROVIDER: S-EPMC3357923 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature