The Hepta-? -Glucoside Elicitor-Binding Proteins from Legumes Represent a Putative Receptor Family

Mithöfer, Axel; Fliegmann, Judith; Neuhaus-Url, Gabriele; Schwarz, Heinz; Ebel, Jürgen

doi:10.1515/bc.2000.091

Cited by 73 publications

(72 citation statements)

References 29 publications

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“…Of saccharide elicitors, a hepta-b-glucoside from cell walls of P. sojae displayed a low K d (0.75 nM) for binding to soybean (Glycine max) membranes (Cheong and Hahn, 1991). A b-glucan-binding protein was identified (Umemoto et al, 1997;Mithö fer et al, 2000) that contains a 1,3-b-glucanase domain releasing oligoglucoside fragments that constitute ligands for the high-affinity binding domain (Fliegmann et al, 2004). Furthermore, chitin perception has been studied in several plants.…”

Section: Discussion Fungal Effector Protein Nip1 Interacts With a Sinmentioning

confidence: 99%

A Single Binding Site Mediates Resistance- and Disease-Associated Activities of the Effector Protein NIP1 from the Barley Pathogen Rhynchosporium secalis

2007

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The effector protein NIP1 from the barley (Hordeum vulgare) pathogen Rhynchosporium secalis specifically induces the synthesis of defense-related proteins in cultivars of barley expressing the complementary resistance gene, Rrs1. In addition, it stimulates the activity of the barley plasma membrane H 1 -ATPase in a genotype-unspecific manner and it induces necrotic lesions in leaf tissues of barley and other cereal plant species. NIP1 variants type I and II, which display quantitative differences in their activities as elicitor and H 1 -ATPase stimulator, and the inactive mutant variants type III* and type IV*, were produced in Escherichia coli. Binding studies using 125 I-NIP1 type I revealed a single class of binding sites with identical binding characteristics in microsomes from near-isogenic resistant (Rrs1) and susceptible (rrs1) barley. Binding was specific, reversible, and saturable, and saturation ligand-binding experiments yielded a K d of 5.6 nM. A binding site was also found in rye (Secale cereale) and the nonhost species wheat (Triticum aestivum), oat (Avena sativa), and maize (Zea mays), but not in Arabidopsis (Arabidopsis thaliana). For NIP1 types I and II, equilibrium competition-binding experiments revealed a correlation between the difference in their affinities to the binding site and the differences in their elicitor activity and H 1 -ATPase stimulation, indicating a single target molecule to mediate both activities. In contrast, the inactive proteins type III* and type IV* are both characterized by high affinities similar to type I, suggesting that binding of NIP1 to this target is not sufficient for its activities.

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Section: Discussion Fungal Effector Protein Nip1 Interacts With a Sinmentioning

confidence: 99%

A Single Binding Site Mediates Resistance- and Disease-Associated Activities of the Effector Protein NIP1 from the Barley Pathogen Rhynchosporium secalis

2007

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“…Heterologous Expression-The cDNA encoding the GBP from soybean was expressed in Spodoptera frugiperda cells (Sf9) using the Bac-to-Bac system (Invitrogen) (21). Two different expression constructs were used, one using the endogenous translational initiator codon, and the second, which was engineered to additionally express a NH 2 -terminal fused signal peptide originating from the glycoprotein 67 (GP67) as present in the vector series pAcGP67 (BD Pharmingen, Dianova).…”

Section: Methodsmentioning

confidence: 99%

“…How these different mechanisms contribute to plant defense is not yet understood (24). The existence of GBP-related proteins and transcripts was proved in other species of the Fabaceae, such as Medicago sativa, Lupinus multilupa, and very likely Pisum sativum by Northern and Western blotting experiments (21). These plants have been previously shown to display high affinity binding sites for the ␤-glucan elicitor and to respond to these compounds by inducing the production of phytoalexins (25).…”

mentioning

confidence: 99%

An Ancient Enzyme Domain Hidden in the Putative β-Glucan Elicitor Receptor of Soybean May Play an Active Part in the Perception of Pathogen-associated Molecular Patterns during Broad Host Resistance

Fliegmann

Mithöfer

Wanner

et al. 2004

Journal of Biological Chemistry

146

115

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A successful defense against potential pathogens requires that a host organism is able to discriminate between self and nonself structures. Soybean (Glycine max L.) exploits a specific molecular pattern, a 1,6-␤-linked and 1,3-␤-branched heptaglucoside (HG), present in cell walls of the oomycetal pathogen Phytophthora sojae, as a signal compound eliciting the onset of defense reactions. The specific and high affinity HG-binding site is contained in the ␤-glucan-binding protein (GBP), which in turn is part of a proposed receptor complex. The ability to perceive and respond to Phytophthora cell wall-derived ␤-glucan elicitors is exclusive to plants that belong to the Fabaceae. However, we propose that the presence of the GBP is essential, but not sufficient for ␤-glucan elicitor-dependent disease resistance because genes encoding GBP-related proteins can be retrieved from many plant species. Furthermore, we show that the GBP is composed of two different carbohydrateactive protein domains, one containing the ␤-glucanbinding site, and the other related to glucan endoglucosidases of fungal origin. The glucan hydrolase displays most likely an endo-specific mode of action, cleaving only 1,3-␤-D-glucosidic linkages of oligoglucosides consisting of at least four moieties. Thus, the intrinsic endo-1,3-␤-glucanase activity of the GBP is perfectly suited during initial contact with Phytophthora to release oligoglucoside fragments enriched in motifs that constitute ligands for the high affinity binding site present in the same protein. The concept of innate immunity in plants receives substantial support by this highly sophisticated system using ancient enzyme modules as an active part of the recognition mechanism.

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“…Legumes are the only plant group that possess the β-heptaglucoside receptor and the ability to mount a defence response to this elicitor 140 .…”

Section: Rhizobial Evasion Of Plant Innate Immunitymentioning

confidence: 99%

How rhizobial symbionts invade plants: the Sinorhizobium–Medicago model

et al. 2007

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Nitrogen-fixing rhizobial bacteria and leguminous plants have evolved complex signal exchange mechanisms that allow a specific bacterial species to induce its host plant to form invasion structures through which the bacteria can enter the plant root. Once the bacteria have been endocytosed within a host-membrane-bound compartment by root cells, the bacteria differentiate into a new form that can convert atmospheric nitrogen into ammonia. Bacterial differentiation and nitrogen fixation are dependent on the microaerobic environment and other support factors provided by the plant. In return, the plant receives nitrogen from the bacteria, which allows it to grow in the absence of an external nitrogen source. Here, we review recent discoveries about the mutual recognition process that allows the model rhizobial symbiont Sinorhizobium meliloti to invade and differentiate inside its host plant alfalfa (Medicago sativa) and the model host plant barrel medic (Medicago truncatula).The recent completion of the Sinorhizobium meliloti genome sequence, and the progress towards the completion of the Medicago truncatula genome sequence, have led to a surge in the molecular characterization of the determinants that are involved in the development of the symbiosis between rhizobial bacteria and leguminous plants. Aromatic compounds from legumes called flavonoids first signal the rhizobial bacteria to produce lipochitooligosaccharide compounds called Nod factors 1 . Nod factors that are secreted by the bacteria activate multiple responses in the host plant that prepare the plant to receive the invading bacteria. Nod factors and symbiotic exopolysaccharides induce the plant to form infection threads, which are thin tubules filled with bacteria that penetrate into the plant cortical tissue and deliver the bacteria to their target cells. Plant cells in the inner cortex internalize the invading bacteria in host-membrane-bound compartments that mature into structures known Correspondence to G.C.W. gwalker@mit.edu. Competing interests statementThe authors declare no competing financial interests. DATABASES Invasion of plant rootsAlthough plant roots are exposed to various micro-organisms in the soil, their cell walls form a strong protective barrier against most harmful species. The early steps in the invasion of barrel medic (M. truncatula) and alfalfa (Medicago sativa) roots by S. meliloti are characterized by the reciprocal exchange of signals that allow the bacteria to use the plant root hair cells as a means of entry. Initial signal exchangeFlavonoid compounds (2-phenyl-1,4-benzopyrone derivatives) produced by leguminous plants are the first signals to be exchanged by host-rhizobial symbiont pairs 1 (FIG. 1). Flavonoids bind bacterial NodD proteins, which are members of the LysR family of transcriptional regulators, and activate these proteins to induce the transcription of rhizobial genes 1,2 . For example, the M. sativa-derived flavonoid luteolin stimulates binding of an active form of NodD1 to an S. meliloti 'nod-box' p...

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The Hepta-? -Glucoside Elicitor-Binding Proteins from Legumes Represent a Putative Receptor Family

Cited by 73 publications

References 29 publications

A Single Binding Site Mediates Resistance- and Disease-Associated Activities of the Effector Protein NIP1 from the Barley Pathogen Rhynchosporium secalis

A Single Binding Site Mediates Resistance- and Disease-Associated Activities of the Effector Protein NIP1 from the Barley Pathogen Rhynchosporium secalis

An Ancient Enzyme Domain Hidden in the Putative β-Glucan Elicitor Receptor of Soybean May Play an Active Part in the Perception of Pathogen-associated Molecular Patterns during Broad Host Resistance

How rhizobial symbionts invade plants: the Sinorhizobium–Medicago model

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