The nitrogenase complex carries out the fixation of nitrogen by reducing molecular dinitrogen (N2) to ammonium (NH4 1 ) and also reduces acetylene to ethylene. The two component proteins are dinitrogenase and dinitrogenase reductase. Although different metals can form the metal clusters contained in nitrogenase proteins, all nitrogenases have similar properties. The nitrogenase enzyme system is...

Rhodopseudomonas palustris is a photosynthetic bacterium that can use many forms of carbon, nitrogen, and electron donors. Under anaerobic conditions it can generate energy from light and convert nitrogen gas to ammonia and hydrogen (a biofuel) by nitrogen fixation. A striking feature of the genome sequence of R. palustris CGA009 is genes encoding three different nitrogenases and the accessory ...

The photosynthetic bacterium Rhodobacter capsulatus has been shown to carry out nitrogenase "switch-off," a rapid, reversible inhibition of in vivo activity. Here, we demonstrate that highly nitrogen-limited cultures of both the wild-type strain and a draT draG mutant are capable of nitrogenase switch-off while moderately nitrogen-limited cultures show instead a "magnitude" response, with a dec...

The enzymatic mechanisms and energetics o f nitrogenase-catalyzed photoproduction o f hydrogen from organic C-compounds by purple bacteria are discussed in respect to the ques­ tion o f which o f the following three enzymes or enzyme systems are rate limiting for H2-production: (a) the nitrogenase-complex; (b) the enzymes and electron transport proteins involved in hydrogen transfer from the or...

A large number of genes are necessary for the biosynthesis and activity of the enzyme nitrogenase to carry out the process of biological nitrogen fixation (BNF), which requires large amounts of ATP and reducing power. The multiplicity of the genes involved, the oxygen sensitivity of nitrogenase, plus the demand for energy and reducing power, are thought to be major obstacles to engineering BNF ...

Anabaena variabilis ATCC 29413 fixes nitrogen in specialized cells called heterocysts using either a Mo-nitrogenase or a V-nitrogenase. V-nitrogenase structural genes, vnfDGK, as well as vnfEN form an operon with ava4025, located upstream of vnfDG that is repressed by fixed nitrogen and by Mo. The ava4025-vnfDGKEN operon is under the control of a Mo-repressible promoter located nearly 600 bp up...

The industrial production and use of nitrogenous fertilizer involves significant environmental and economic costs. Strategies to reduce fertilizer dependency are required to address the world's increasing demand for sustainable food, fibers, and biofuels. Biological nitrogen fixation, a process unique to diazatrophic bacteria, is catalyzed by the nitrogenase complex, and reconstituting this fun...

The Mo- and V-nitrogenases are two homologous members of the nitrogenase family that are distinguished mainly by the presence of different heterometals (Mo or V) at their respective cofactor sites (M- or V-cluster). However, the V-nitrogenase is ~600-fold more active than its Mo counterpart in reducing CO to hydrocarbons at ambient conditions. Here, we expressed an M-cluster-containing, hybrid ...

Biological nitrogen fixation by the Rhizobium -legume symbiosis allows conversion of atmospheric into ammonia within root nodules mediated nitrogenase enzyme. Nitrogenase activity results in evolution hydrogen as a result side reaction intrinsic to this Some rhizobia, and also other fixers, induce NiFe uptake hydrogenase (Hup) recycle produced nitrogenase, thus improving efficiency process. In ...

Nitrogenase is an essential metalloenzyme that catalyzes the biological conversion of dinitrogen (N(2)) to ammonia (NH(3)). The vanadium (V)-nitrogenase is very similar to the "conventional" molybdenum (Mo)-nitrogenase, yet it holds unique properties of its own that may provide useful insights into the general mechanism of nitrogenase catalysis. So far, characterization of the vanadium iron (VF...