Three unusual modifications, a D-arabinosyl, an N-methyl, and a carbamoyl group, are present on the Nod factors of Azorhizobium caulinodans strain ORS571.
Azorhizobium caulinodans strain ORS571 is a symbiont of the tropical legume Sesbania rostrata. Upon nod gene induction with naringenin, strain ORS571 secretes into the culture medium Nod factors that morphologically change the host plant--in particular, deformed root hairs (Hai/Had) and meristematic foci are formed at the basis of lateral roots. The latter infrequently develop further into nodule-like structures. The azorhizobial Nod factors are chitin tetramers or pentamers, N-acylated at the nonreducing-end glucosamine with either vaccenic acid (C18:1) or stearic acid (C18:0). They, thus, resemble the previously described Nod factors from (brady)rhizobia. The backbone lipooligosaccharide is substituted with unusual modifications, presumably involved in host-specificity determination. There is a D-arabinose branch on the reducing end and an N-methyl and O-carbamoyl substitution on the nonreducing end of the oligosaccharide chain. The previously identified nod gene nolK may be involved in the synthesis of a D-arabinose derivative. The nodS gene product is probably responsible for the N-methylation of Nod factors.
Mergaert
P
P
Laboratorium voor Genetica, Universiteit Gent, Belgium.
Van Montagu
M
M
Promé
J C
JC
Holsters
M
M
D001089:Arabinose / Q000032:analysis*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D007887:Fabaceae; D005798:Genes, Bacterial; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry* / Q000302:isolation & purification; D010946:Plants, Medicinal; D012230:Rhizobiaceae / Q000737:chemistry* / Q000235:genetics; D016339:Spectrometry, Mass, Fast Atom Bombardment
D001426:Bacterial Proteins; D009844:Oligosaccharides; D001089:Arabinose