A Proteomic Atlas of the Legume Medicago Truncatula and Its Nitrogen-Fixing Endosymbiont Sinorhizobium Meliloti

Nat Biotechnol. 2016 Nov;34(11):1198-1205. doi: 10.1038/nbt.3681. Epub 2016 Oct 17.


Legumes are essential components of agricultural systems because they enrich the soil in nitrogen and require little environmentally deleterious fertilizers. A complex symbiotic association between legumes and nitrogen-fixing soil bacteria called rhizobia culminates in the development of root nodules, where rhizobia fix atmospheric nitrogen and transfer it to their plant host. Here we describe a quantitative proteomic atlas of the model legume Medicago truncatula and its rhizobial symbiont Sinorhizobium meliloti, which includes more than 23,000 proteins, 20,000 phosphorylation sites, and 700 lysine acetylation sites. Our analysis provides insight into mechanisms regulating symbiosis. We identify a calmodulin-binding protein as a key regulator in the host and assign putative roles and targets to host factors (bioactive peptides) that control gene expression in the symbiont. Further mining of this proteomic resource may enable engineering of crops and their microbial partners to increase agricultural productivity and sustainability.

MeSH terms

  • Bacterial Proteins / metabolism*
  • Databases, Protein
  • Medicago truncatula / metabolism*
  • Medicago truncatula / microbiology*
  • Nitrogen Fixation / physiology*
  • Plant Proteins / metabolism*
  • Proteome / metabolism
  • Proteomics
  • Sinorhizobium meliloti / physiology*
  • Symbiosis / physiology*


  • Bacterial Proteins
  • Plant Proteins
  • Proteome