Lipo-chitooligosaccharidic nodulation factors and their perception by plant receptors

Abstract

Lipo-chitooligosaccharides produced by nitrogen-fixing rhizobia are signaling molecules involved in the establishment of an important agronomical and ecological symbiosis with plants. These compounds, known as Nod factors, are biologically active on plant roots at very low concentrations indicating that they are perceived by specific receptors. This article summarizes the main strategies developed for the syntheses of bioactive Nod factors and their derivatives in order to better understand their mode of perception. Different Nod factor receptors and LCO-binding proteins identified by genetic or biochemical approaches are also presented, indicating perception mechanisms that seem to be more complicated than expected, probably involving multi-component receptor complexes.

The Structural Basis of Ligand Perception and Signal Activation by Receptor Kinases

“…These modules are also present in viral, bacterial, fungal, and animal proteins and are able to recognize carbohydrates that contain N-acetyl-D-glucosamine (NAG) (13). Plant RKs with LysM-containing ectodomains are involved in sensing symbiotic signals [NAG-containing nodulation (Nod) factors] to establish, for example, rhizobia and mycorrhiza, and are involved in plant immune responses by recognizing the NAG-containing chitin and peptidoglycan cell walls of fungal and bacterial invaders (2,34). The Lotus japonicus NODULATION FACTOR RECEPTOR 1/5 (NFR1/5) and Medicago truncatula LYSM DOMAIN-CONTAINING RECEPTOR-LIKE KINASE-RELATED 3 (MtLYR3) participate in the recognition of Nod factors consisting of four or five β-1,4-linked NAGs with an alkyl chain at the C-2 position of the nonreducing terminal glucosamine residue (11,35,73,78,79,98,121,135).…”

“…The first LysM-domain structure from Escherichia coli revealed a conserved fold characterized by the presence of two α-helices packed against the same surface of a small antiparallel β-sheet (5) (Figure 3a; see also the sidebar titled How to Read Structural Representations). LysM signatures are present in several plant RKs (such as AtCERK1) (5,34,42,54), in receptor-like proteins (RLPs) [such as Oryza sativa CHITIN ELICITOR BINDING PROTEIN (OsCEBiP)] (23,24,49,62), and in cell surface glycosylphosphatidylinositol (GPI)-anchored proteins (8) (Figure 1).…”

A Laser Dissection-RNAseq Analysis Highlights the Activation of Cytokinin Pathways by Nod Factors in the Medicago truncatula Root Epidermis

“…Expression of the NF receptor gene NFP was apparently not affected by the NF treatment, in contrast to what was reported by Breakspear et al (2014), while the closely related LYK2 and LYK3 genes were downregulated (Supplemental Table S4). Four other LYSM-RLK genes from three distinct subgroups (Arrighi et al, 2006) were up-regulated (Table III; Supplemental Table S3): LYR3, which encodes a high-affinity LCO-binding protein (Fliegmann et al, 2013;Fliegmann and Bono, 2015); LYR6, of unknown function, a chitin receptor CERK1-like gene; and, more strikingly, LYK10, the ortholog of LjEPR3 recently described as encoding a receptor of Rhizobium spp. exopolysaccharide (Kawaharada et al, 2015), required for rhizobial infection in L. japonicus.…”

Plant-Microbe Interactions: A Molecular Approach

“…Membrane reorganization, cytoplasmic streaming, microtubule reaggregation, and other mechanical responses are also observed in combination with the molecular reactions in response to a microbial infection (Ueda et al 2015 ). Extracellular ATP or eATP acts as a signaling molecule to cause the activation of a number of effector molecules including lectin nucleotide phosphohydrolase (LNP) and other kinases through G-protein complexes (Fliegmann and Bono 2015 ).…”