Mutational analysis of the Sinorhizobium meliloti short-chain dehydrogenase/reductase family reveals substantial contribution to symbiosis and catabolic diversity

Asha I. Jacob, Sirin A I Adham, David S. Capstick, Scott R D Clark, Tara Spence, Trevor C. Charles

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19 Citations (Scopus)


The short-chain dehydrogenase/reductase (SDR) family is one of the largest and most ubiquitous protein families in bacterial genomes. Despite there being a few well-characterized examples, the substrate specificities or functions of most members of the family are unknown. In this study, we carried out a large-scale mutagenesis of the SDR gene family in the alfalfa root nodule symbiont Sinorhizobium meliloti. Subsequent phenotypic analysis revealed phenotypes for mutants of 21 of the SDR-encoding genes. This brings the total number of S. meliloti SDR-encoding genes with known function or associated phenotype to 25. Several of the mutants were deficient in the utilization of specific carbon sources, while others exhibited symbiotic deficiencies on alfalfa (Medicago sativa), ranging from partial ineffectiveness to complete inability to form root nodules. Five of the mutants had both symbiotic and carbon utilization phenotypes. These results clearly demonstrate the importance of the SDR family in both symbiosis and saprotrophy, and reinforce the complex nature of the interaction of S. meliloti with its plant hosts. Further analysis of the genes identified in this study will contribute to the overall understanding of the biology and metabolism of S. meliloti in relation to its interaction with alfalfa.

Original languageEnglish
Pages (from-to)979-987
Number of pages9
JournalMolecular Plant-Microbe Interactions
Issue number7
Publication statusPublished - Jul 2008


ASJC Scopus subject areas

  • Microbiology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biotechnology

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