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Updated: Aug 14, 2026

Generation of Marked and Markerless Mutants in Model Cyanobacterial Species
Published on: May 29, 2016
Mutation in ntrC gene leading to the derepression of nitrogenase synthesis in Rhodobacter sphaeroides
V Zinchenko1, M Babykin, V Glaser
1Department of Genetics, Moscow State University, Russia. vzin@string.stringer.ru
Abstract:
The Rhodobacter sphaeroides mutants Drn12 and Drn21 derepressed for nitrogenase synthesis in the presence of ammonia and impaired in utilization of certain nitrogen sources have been analyzed. Both mutants show a low level of expression of the glnBA operon. The DNA fragment restoring the wild-type phenotype to these mutants contains the 3'-portion of ntrB gene and the entire ntrC gene. Sequence analysis showed that Drn12 bears a missense mutation in the ntrC gene. The mutation results in the replacement of a glycine residue by aspartate within the N-terminal domain of the NtrC protein. Pleiotropic phenotypes of Drn12 and Drn21 appear to be associated with an alteration in the regulation of glnBA expression.
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