PMID:8801423
| Citation |
Ardourel, M, Lortet, G, Maillet, F, Roche, P, Truchet, G, Promé, JC and Rosenberg, C (1995) In Rhizobium meliloti, the operon associated with the nod box n5 comprises nodL, noeA and noeB, three host-range genes specifically required for the nodulation of particular Medicago species. Mol. Microbiol. 17:687-99 |
|---|---|
| Abstract |
In Rhizobium meliloti, the genes required for nodulation of legume hosts are under the control of DNA regulatory sequences called nod boxes. In this paper, we have characterized three host-specific nodulation genes, which form a flavonoid-inducible operon down-stream of the nod box n5. The first gene of this operon is identical to the nodL gene identified by Baev and Kondorosi (1992) in R. meliloti strain AK631. The product of the second gene, NoeA, presents some homology with a methyltransferase. nodL mutants synthesize Nod factors lacking the O-acetate substituent. In contrast, in strains carrying a mutation in either noeA or noeB, no modification in Nod-factor structure or production could be detected. On particular hosts, such as Medicago littoralis, mutants of the n5 operon showed a very weak nodule-forming ability, associated with a drastic decrease in the number of infection threads, while nodulation of Medicago truncatula or Melilotus alba was not affected. Thus, nodL noeA and noeB are host-specific nodulation genes. By using a gain-of-function approach, we showed that the presence of nodL, and hence of O-acetylated Nod factors, is a major prerequisite for confering the ability to nodulate alfalfa upon the heterologous bacterium Rhizobium tropici. |
| Links | |
| Keywords |
Acetylation; Acetyltransferases/genetics; Amino Acid Sequence; Bacterial Proteins/genetics; Carbohydrate Sequence; Chromosome Mapping; Genes, Bacterial/genetics; Lipopolysaccharides/biosynthesis; Lipopolysaccharides/chemistry; Medicago sativa/microbiology; Molecular Sequence Data; Open Reading Frames; Operon; Plant Roots/microbiology; Regulatory Sequences, Nucleic Acid; Regulon; Sequence Analysis, DNA; Sinorhizobium meliloti/genetics; Species Specificity; Symbiosis |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
See also
References
See Help:References for how to manage references in EcoliWiki.
