Homology of Rhizobium meliloti NodC to polysaccharide polymerizing enzymes.

Rhizobium bacteria form nitrogen-fixing nodules on legume roots. As part of the nodulation process, they secrete Nod factors that are beta-1,4-linked oligomers of N-acetylglucosamine. These factors depend on nodulation (nod) genes, but most aspects of factor synthesis are not yet known. We show here that one gene, nodC, shows striking similarity to genes encoding proteins known to be involved in polysaccharide synthesis in yeast and bacteria, specifically chitin and cellulose synthases, as well as a protein with unknown function in Xenopus embryos, DG42. This similarity is consistent with a role for the NodC protein in the formation of the beta-1,4-linkage in Nod factors.