Inhibition of nitrogenase activity by NH+4 in Rhodospirillum rubrum

Identification of an alternative nitrogenase system in Rhodospirillum rubrum.

A second nitrogenase activity has been demonstrated in Rhodospirillum rubrum. This nitrogenase is expressed whenever a strain lacks an active Mo nitrogenase because of physiological or genetic inactivation. The alternative nitrogenase is able to support growth on N2 in the absence of fixed N. V does not stimulate, nor does Mo or W inhibit, growth or activity under the conditions tested. The pro...

Effect of an ntrBC mutation on the posttranslational regulation of nitrogenase activity in Rhodospirillum rubrum.

Homologs of ntrB and ntrC genes from Rhodospirillum rubrum were cloned and sequenced. A mutant lacking ntrBC was constructed, and this mutant has normal nitrogenase activity under nif-derepressing conditions, indicating that ntrBC are not necessary for the expression of the nif genes in R. rubrum. However, the post-translational regulation of nitrogenase activity by ADP-ribosylation in response...

Effect of pyruvate on the metabolic regulation of nitrogenase activity in Rhodospirillum rubrum in darkness.

Rhodospirillum rubrum, a photosynthetic diazotroph, is able to regulate nitrogenase activity in response to environmental factors such as ammonium ions or darkness, the so-called switch-off effect. This is due to reversible modification of the Fe-protein, one of the two components of nitrogenase. The signal transduction pathway(s) in this regulatory mechanism is not fully understood, especially...

Effect of perturbation of ATP level on the activity and regulation of nitrogenase in Rhodospirillum rubrum.

Nitrogenase activity in Rhodospirillum rubrum and in some other photosynthetic bacteria is regulated in part by the availability of light. This regulation is through a posttranslational modification system that is itself regulated by P(II) homologs in the cell. P(II) is one of the most broadly distributed regulatory proteins in nature and directly or indirectly senses nitrogen and carbon signal...

Regulation of Rhodospirillum rubrum nitrogenase activity. Properties and interconversion of active and inactive Fe protein.