Objetivo
Signal exchange mediates specificity in legume-Rhizobium associations. Plant roots excrete many compounds, amongst which are flavonoids that activate nodulation genes within the bacteria. In turn, these nodulation proteins direct the synthesis of lipo-oligosaccharides (Nod-factors) which induce root-hair curling and nodulation on the legume. Therefore, several lipo-oligosaccharides will be synthesized in the framework of this project and screened for their biological activity.
Rhizobia that are capable of nodulating many legumes secrete various highly modified Nod-factors. For example, Rhizobium sp. NGR234, which nodulates more than 100 legume genera, produces at least 36 different Nod-factors. Amongst them are molecules in which the terminal non-reducing glucosamine is N-acylated with vaccenic or palmitic acids, is N-methylated, and carries one or two carbamoyl groups. The reducing N-acetyl-glucosamine residue is substituted on position 6 with 2-O-methyl-L-fucose which may be acetylated, or sulphated, or non-substituted. All three internal residues are N-acetylated. At pico- to nano-molar concentrations, these signal molecules exhibit symbiotic activity. Some of these NodNGR factors are necessary for the nodulation of a particular plant, others for different legumes. To confirm the structures, and to isolate legume proteins involved in reception/binding, the Nod-factors of Rhizobium sp. NGR234 will be completely synthesised.
Convocatoria de propuestas
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1292 Chambésy - Genève
Suiza