Induction of C4-dicarboxylate transport genes by external stimuli in Rhizobium meliloti
- 1 January 1992
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Microbiology
- Vol. 38 (1) , 51-55
- https://doi.org/10.1139/m92-008
Abstract
We have characterized two mutants of Rhizobium meliloti L5-30 obtained by random mutagenesis using Mu–lacZ that were defective in transport of C4-dicarboxylic acids. These mutants induced ineffective nodules on alfalfa. Mutations in the two strains appeared to be located in a dctA gene. Levels of dctA gene expression were determined under different environmental conditions using dctA–lacZ fusions, and β-galactosidase activities increased in response to osmotic stress and also when the cells were incubated in medium low in calcium. The transcriptional induction of the dctA gene by environmental signals was decreased by DNA gyrase inhibitors such as novobiocin and coumermycin. Key words: Rhizobium meliloti, nitrogen fixation, dicarboxylate transport.Keywords
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