| Autor: |
Boivin, C, Barran, L R, Malpica, C A, Rosenberg, C |
| Zdroj: |
Journal of Bacteriology; May 1991, Vol. 173 Issue: 9 p2809-2817, 9p |
| Abstrakt: |
Genes controlling the catabolism of trigonelline, a secondary metabolite that is often present in legumes, are located on the pSym megaplasmid of Rhizobium meliloti. To investigate the role of bacterial trigonelline catabolism in the Rhizobium-legume symbiosis, we identified and characterized the R. meliloti RCR2011 genetic loci (trc) controlling trigonelline catabolism. Tn5-B20 mutagenesis showed that the trc region is a continuous DNA segment of 9 kb located 4 kb downstream of the nifAB and fdxN genes. Trc mutants fell into two classes according to their phenotype and location: (i) mutants carrying Tn5-B20 insertions in the right-hand part of the trc region were incapable of growing on trigonelline as the sole carbon and/or nitrogen source, and (ii) insertions in the left-hand part of the trc region resulted in delayed growth on trigonelline as the sole carbon and/or nitrogen source. No significant defect in nodule formation or nitrogen fixation was detected for mutants of either class. Screening of a set of R. meliloti strains from various geographical origins showed that all of these strains are able to catabolize trigonelline and show sequence homology between their megaplasmids and a trc probe. |
| Databáze: |
Supplemental Index |
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