Characterization of a binding site for chemically synthesized lipo‐oligosaccharidic NodRm factors in particulate fractions prepared from roots

Abstract

SummaryThis paper describes the characteristics of a binding site for the major, lipo-oligossccharide Nod factor of Rhizobium meliloti in roots of the symbiotic host plant, Medicago truncatula. Chemically synthesized NodRm-IV(Ac, S, C16:2) was labelled by tritiation to a specific activity of 56 Ci mmo1-1 and this ligand was shown to be biologically active in the root hair deformation assay at 10 -11 M. Binding of the ligand to a particulate fraction from roots of M. truncatula was found to be saturable and reversible with an affinity (K d) of 86 nM and the binding characteristics were consistent with a single class of binding sites. Competition with modified Nod factors showed that the binding was independent of both the (~acotyl and the suIphyl group and did not depend on the uncaturation of the fatty acid. However, both moieties of the lipooligossccharide are required for high-affinity binding since tetra-N-acatyl-chitotetraose and palmitate were found to be poor competitors of Iigand binding. A binding site with analogous characteristics was also found in a similarly prepared particulate fraction of tomato roots. This binding site for Nod factors, termed NFBS1, which is present in both a leguminous and a non-leguminous plant, may have a more general role than symbiosis.

Phytosulfokine-α, a sulfated pentapeptide, stimulates the proliferation of rice cells by means of specific high- and low-affinity binding sites

“…However, we could not detect PSKs' activity in conditioned medium derived from cell cultures of dicotyledonous plants, such as tobacco and Zinnia elegans, suggesting that the growth factor(s) of dicots have different structure(s) from PSKs. This is in line with cross-feeding experiments, which also pointed out incompatibility of factors between monocots and dicots (8,9 M for high-affinity type), but 4 to 10,000 times higher than those for plant signaling molecules, such as the fungal glucan phytoalexin elicitor (23)(24)(25) and lipo-oligosaccharidic NodRm factors (26).…”

Structural Requirements of Synthetic and Natural Product Lipo-Chitin Oligosaccharides for Induction of Nodule Primordia on Glycine soja

“…First, synthetic LCOs are biologically active. Although there are now four published reports of the synthesis of various LCO molecules (Nicolaou et al, 1992;Wang et al, 1993;Ikeshita et al, 1994aIkeshita et al, , 1994b, there has only recently been a published report of HAD activity for synthetic LCOs (Bono et al, 1995). Our study demonstrates that synthetic LCO molecules not only deform root hairs but also induce emerging nodule structures.…”

A nod factor binding lectin with apyrase activity from legume roots

“…High-affinity binding sites for chitin fragments have been found on membranous fractions prepared from tomato (7) and rice (8) suspension-cultured cells, and a 70-kDa protein that binds to chitin fragments was isolated from the rice membranes (9). Particulate fractions from roots of the legume, Medicago truncatula, were found to bind Nod factors produced by the rhizobial symbiont of this plant, and similar binding activity was found in a particulate fraction of tomato roots and the microsomal fraction of Medicago varia cell suspension cultures (10,11).…”

“…Indeed, high-affinity binding sites for Nod factors have been found on particulate fractions from roots of the legume, M. truncatula, and the microsomal fraction of Medicago cellsuspension cultures (10,11). Although the inhibition data in Fig.…”