Posttranslational modification of a vanadium nitrogenase
- Department of Microbiology, University of Washington, Seattle Washington 98195
In microbes that fix nitrogen, nitrogenase catalyzes the conversion of N2 to ammonia in an ATP-demanding reaction. To help conserve energy some bacteria inhibit nitrogenase activity upon exposure to ammonium. The purple nonsulfur phototrophic bacterium Rhodopseudomonas palustris strain CGA009 can synthesize three functional nitrogenase isoenzymes: a molybdenum nitrogenase, a vanadium nitrogenase, and an iron nitrogenase. Previous studies showed that in some alphaproteobacteria, including R. palustris, molybdenum nitrogenase activity is inhibited by ADP-ribosylation when cells are exposed to ammonium. Some iron nitrogenases are also post-translationally modified. However, the posttranslational modification of vanadium nitrogenase has not been reported. Here, we investigated the regulation of the alternative nitrogenases of R. palustris and determined that both its vanadium nitrogenase and its iron nitrogenase activities were inhibited and post-translationally modified when cells are exposed to ammonium. Vanadium nitrogenase is not found in all strains of R. palustris, suggesting that it may have been acquired by horizontal gene transfer. Also, phylogenetic analyses of the three nitrogenases suggest that VnfH, the target of ADP-ribosylation, may be the product of a gene duplication of nifH, the molybdenum nitrogenase homolog.
- Research Organization:
- Univ. of Washington, Seattle, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- FG02-05ER15707
- OSTI ID:
- 1623573
- Journal Information:
- MicrobiologyOpen, Vol. 4, Issue 4; ISSN 2045-8827
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ammonium inhibition of nitrogenase activity in Herbaspirillum seropedicae
The Shifts of Diazotrophic Communities in Spring and Summer Associated with Coral Galaxea astreata, Pavona decussata, and Porites lutea