INTRODUCTION .......................................... 235 PROPERTIES OF THE NITROGENASE PROTEINS ................... 237 Fe-Protein ............................................ 238 MoFe-Protein .......................................... 241 Species-Specific Variations in Nitrogenase Proteins ................... 245 GENETICS AND ASSEMBLY OF TIIE NITROGENASE PROTEINS ........ 246 MECHANISM OF N...

Growth and symbiotic activity of legumes are mediated by Nod factors (LCO, lipo-chitooligosaccharides). To assess the effects of application of Nod factors on symbiotic activity and yield of pea, a two-year field experiment was conducted on a Haplic Luvisol developed from loess. Nod factors were isolated from Rhizobium leguminosarum bv. viciae strain GR09. Pea seeds were treated with the Nod fa...

The filamentous cyanobacterium Anabaena variabilis fixes nitrogen in the presence of vanadium (V) and in the absence of molybdenum (Mo), using a V-dependent nitrogenase (V-nitrogenase) encoded by the vnfDGK genes. Downstream from these genes are two genes that are similar to the vnfEN genes of Azotobacter vinelandii. Like the vnfDGK genes, the vnfEN genes were transcribed in the absence of Mo, ...

Nitrogen fixation of Medicago truncatula is regulated by the nitrogen status of leaves through inducing a repeatedly occurring 24-h nodule activity rhythm that reduces per day nitrogen fixation. The hypotheses of the present study were that (1) long-term moderate whole-plant P deficiency in Medicago truncatula induces an according daily rhythm in nitrogenase activity comparable to that induced ...

During photo-fermentative H(2) production, the effects of carbon and nitrogen sources on nitrogenase and hydrogenase activity, poly-β-hydroxybutyrate accumulation were investigated. In succinate/ammonium sulfate medium, H(2) was not detected for the first 6h because high ammonium concentration considerably reduced the nitrogenase activity to below 5 nmol/g-dcw/h. After 24h, 99% of the ammonium ...

Frankia strain HFP ArI3 which had been preserved for 27 months by being lyophilized, frozen in glycerol, or stored in complex medium was successfully used as an inoculum after being subcultured for inducing nodulation and nitrogen fixation of Alnus rubra. Glycerol-preserved HFP ArI3 produced significantly lower rates of nitrogenase activity than did lyophilized or complex-medium-preserved inocu...

One of the main hurdles to engineer nitrogenase in a non-diazotrophic host is achieving NifB activity. NifB is an extremely unstable and oxygen sensitive protein that catalyzes a low-potential SAM-radical dependent reaction. The product of NifB activity is called NifB-co, a complex [8Fe-9S-C] cluster that serves as obligate intermediate in the biosyntheses of the active-site cofactors of all kn...

Root nodules were harvested from chamber-grown soybean (Glycine max L. Merril cv Woodworth) plants throughout development. Apparent nitrogenase activity (acetylene reduction) peaked before seeds began to develop, but a significant amount of activity remained as the seeds matured. Nodule senescence was defined as the period in which residual nitrogenase activity was lost. During this time, solub...

Nitrate-fed and dark-stressed bean (Phaseolus vulgaris) and pea (Pisum sativum) plants were used to study nodule senescence. In bean, 1 d of nitrate treatment caused a partially reversible decline in nitrogenase activity and an increase in O(2) diffusion resistance, but minimal changes in carbon metabolites, antioxidants, and other biochemical parameters, indicating that the initial decrease in...

In R. capsulatus synthesis and activity of the molybdenum and the alternative nitrogenase is controlled at three levels by the environmental factors ammonium, molybdenum, light, and oxygen. At the first level, transcription of the nifA1, nifA2, and anfA genes--which encode the transcriptional activators of all other nif and anf genes, respectively--is controlled by the Ntr system in dependence ...