Structural determination of symbiotic nodulation factors from the broad host-range Rhizobium species NGR234

Nod factors are secreted lipo-oligosaccharides produced by symbiotic nitrogen-fixing Rhizobium bacteria that induce nodule formation on the roots of host leguminous plants. Two biologically active fractions (NodNGR(A) and NodNGR) were isolated by reversed-phase HPLC from the culture supernatant of a Nod factor overproducing strain of Rhizobium sp. NGR234, NodNGR(A) and NodNGR(B) are heterogeneous mixtures of N-acylated 2-O-methylfucosylated chitomers, in which the fucosyl residue may be either 3-sulfated (NodNGR(A)), or 4-O-acetylated or nonsubstituted (NodNGR(B)). Structurally analogous series of compounds occur with either N-vaccenic (C18:1) or N-palmitic (C16:0) substituents. The presence of 6-O-carbamoyl groups on the GlcNMeAcyl residue occurs on some molecules, while others are di-O-carbamoylated.