Differential roles of HypC and HupF proteins for hydrogenase synthesis in Rhizobium leguminosarum.

Resumen

Some diazotrophic bacteria induce [NiFe] hydrogenases to recycle the hydrogen evolved by nitrogenase during the nitrogen fixation process. Biosynthesis of Rhizobium leguminosarum [FeNi] hydrogenase requires a number of accessory proteins (products of hup and hyp genes) that mediate the incorporation of Ni and Fe into the active site. Among them, HypC-paralog HupF and HupK are present in bacteria that synthesize hydrogenase in the presence of oxygen. Hydrogenase activity in mutant strains lacking either hupF or hypC genes was severely reduced, indicating that both proteins are essentials for biosynthesis of hydrogenase. Co-purification of StrepTag labelled variants of HupF and HypC by an affinity chromatography-based approach demonstrated interactions between HupL-HupF and HypC-HupK. Experiments carried out with strains induced for hydrogenase under 3% oxygen tensions indicated that HupF might provide additional stability to HupL under these conditions