Elicitor-Mediated Oligomerization of the Tobacco N Disease Resistance Protein

Mestre, Pere; Baulcombe, David C.

doi:10.1105/tpc.105.037234

Cited by 236 publications

(225 citation statements)

References 43 publications

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“…The TIR domain of vertebrate TLR proteins mediates homotypic protein-protein interactions with downstream signaling molecules also having a TIR domain70 , 71. In plants, there is no experimental evidence to support the idea of a similar function for the TIR domain, although homotypic TIR interactions have been identified in NBS-LRR oligomerization, as discussed in more detail below 72 .…”

Section: Functions Of the Amino-terminal Domainmentioning

confidence: 97%

“…In addition, downstream signal-transduction mutants do not affect the formation of oligomers, suggesting that the formation of oligomers is an early event in pathogen detection 72 . Notably, experimental evidence suggests that RPS5 may form oligomers before recognition of pathogen effectors.…”

Section: Nbs-lrr Formation Of Oligomersmentioning

confidence: 99%

“…and R.W.I., unpublished data). An intact Ploop seems to be necessary for the formation of N oligomers, suggesting that the NBS domain is important for this function; however, difficulties with NBS domain expression have precluded direct testing of NBS oligomerization of N protein 72 . Additionally, substitutions in the kinase 1a domain of N protein result in loss of oligomer formation, further indicating involvement of the NBS domain in plant NBS-LRR oligomerization72.…”

Section: Nbs-lrr Formation Of Oligomersmentioning

confidence: 99%

“…The N protein of tobacco forms oligomers in the presence of the pathogen effector, but the TIR domain is the only domain directly associated with that oligomerization 72 . Notably, the amino-terminal coiled-coil domain of RPS5 also forms oligomers, suggesting that for plant NBS-LRR proteins, the amino-terminal domain be involved in the formation of oligomers, which differs from Apaf-1 and CED-4 (B.J.D.…”

Section: Nbs-lrr Formation Of Oligomersmentioning

confidence: 99%

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Plant NBS-LRR proteins in pathogen sensing and host defense

2006

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Plant proteins belonging to the nucleotide-binding site-leucine-rich repeat (NBS-LRR) family are used for pathogen detection. Like the mammalian Nod-LRR protein 'sensors' that detect intracellular conserved pathogen-associated molecular patterns, plant NBS-LRR proteins detect pathogen-associated proteins, most often the effector molecules of pathogens responsible for virulence. Many virulence proteins are detected indirectly by plant NBS-LRR proteins from modifications the virulence proteins inflict on host target proteins. However, some NBS-LRR proteins directly bind pathogen proteins. Association with either a modified host protein or a pathogen protein leads to conformational changes in the amino-terminal and LRR domains of plant NBS-LRR proteins. Such conformational alterations are thought to promote the exchange of ADP for ATP by the NBS domain, which activates 'downstream' signaling, by an unknown mechanism, leading to pathogen resistance.Plants lack the adaptive immunity that vertebrates rely on to respond to pathogens. To successfully detect and ward off pathogens, plants must rely solely on genes stably encoded in the genome. Although the exact mechanisms of pathogen detection differ, plants, like animals, use two distinct defense 'systems' to recognize and respond to pathogen challenge 1 . Pathogen-associated molecular patterns (PAMPs), such as bacterial flagellin, lipopolysaccharides and fungal-oomycete cellulose-binding elicitor proteins, are recognized by plant transmembrane receptors that activate basal defense, a first line of defense against pathogens that is reminiscent of innate immunity in vertebrates 2, 3. In both plants and animals, it is hypothesized that a biological 'arms race' is occurring, in which pathogens have acquired mechanisms to evade PAMP-triggered immunity by evolving effector molecules that modify the state of the host cell, thereby bypassing or disrupting the first line of defense. Plant evolution has countered with proteins that detect specific effector molecules, a mechanism called 'effector-triggered immunity'1 that amounts to a second line of defense. Plant effector-triggered immunity is more akin to mammalian adaptive immunity in that pathogen effectors, rather than conserved elements such as PAMPs, are specifically recognized. However, unlike the situation in mammalian adaptive immunity, the plant host specificity determinants of effector-triggered immunity are encoded in every cell of an organism.The genes encoding the specificity determinants of effector-triggered immunity are known as resistance (R) genes. Most R genes encode proteins that contain a nucleotide-binding site (NBS) and leucine-rich repeats (LRRs). NBS-LRR proteins are involved in the recognition of specialized pathogen effectors (also called avirulence (Avr) proteins) that are thought to provide virulence function in the absence of the cognate R gene 1 . NBS-LRR proteins are also important in animal innate immune systems; however, in animals they seem to be involved in PAMP recognition rather th...

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Section: Functions Of the Amino-terminal Domainmentioning

confidence: 97%

Section: Nbs-lrr Formation Of Oligomersmentioning

confidence: 99%

Section: Nbs-lrr Formation Of Oligomersmentioning

confidence: 99%

Section: Nbs-lrr Formation Of Oligomersmentioning

confidence: 99%

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Plant NBS-LRR proteins in pathogen sensing and host defense

2006

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“…This ''induced proximity'' of downstream effector proteins is thought to be a key step in the activation of Apaf-1 signaling. In addition, it has recently been reported that the N protein from tobacco, which belongs to the TIR-NBS-LRR subfamily, selfassociates upon activation by the p50 fragment of the replicase protein of tobacco mosaic virus and, furthermore, that the TIR domains by themselves can oligomerize (21). In light of these results, we tested for interactions among RPS5 domains.…”

Section: Pbs1mentioning

confidence: 99%

Indirect activation of a plant nucleotide binding site–leucine-rich repeat protein by a bacterial protease

Ade

DeYoung

Golstein

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

369

404

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Nucleotide binding site-leucine-rich repeat (NBS-LRR) proteins mediate pathogen recognition in both mammals and plants. The molecular mechanisms by which pathogen molecules activate NBS-LRR proteins are poorly understood. Here we show that RPS5, a NBS-LRR protein from Arabidopsis, is activated by AvrPphB, a bacterial protease, via an indirect mechanism. When transiently expressed in Nicotiana benthamiana leaves, full-length RPS5 protein triggered programmed cell death, but only when coexpressed with AvrPphB and a second Arabidopsis protein, PBS1, which is a specific substrate of AvrPphB. Using coimmunoprecipitation analysis, we found that PBS1 is in a complex with the N-terminal coiled coil (CC) domain of RPS5 before exposure to AvrPphB. Deletion of the RPS5 LRR domain caused RPS5 to constitutively activate programmed cell death, even in the absence of AvrPphB and PBS1, and this activation depended on both the CC and NBS domains. The LRR and CC domains both coimmunoprecipitate with the NBS domain but not with each other. Thus, the LRR domain appears to function in part to inhibit RPS5 signaling, and cleavage of PBS1 by AvrPphB appears to release RPS5 from this inhibition. An amino acid substitution in the NBS site of RPS5 that is known to inhibit ATP binding in other NBS-LRR proteins blocked activation of RPS5, whereas a substitution thought to inhibit ATP hydrolysis constitutively activated RPS5. Combined, these data suggest that ATP versus ADP binding functions as a molecular switch that is flipped by cleavage of PBS1.B oth plants and animals employ nucleotide binding siteleucine-rich repeat (NBS-LRR) proteins to mediate detection of pathogen molecules (1). There appear to be at least two distinct mechanisms by which NBS-LRR proteins detect pathogens: either by binding pathogen-derived molecules directly or by sensing the modification of host proteins by pathogen-derived molecules (2). It is presently unclear how either mechanism causes activation of signaling by NBS-LRR proteins. We have been investigating these processes by using the plant NBS-LRR protein RPS5, which mediates detection of the protease AvrPphB from the bacterial pathogen Pseudomonas syringae (3-6).In plants, NBS-LRR proteins were first identified as the products of classically defined disease-resistance genes (R genes) (7-9), which are genes that confer resistance to infection by specific pathogen strains. R gene-mediated resistance is typically manifested by activation of a programmed cell death response referred to as the hypersensitive response (HR) that is localized to the site of pathogen ingress (10). In the last decade, R genes have been cloned from a large range of plant species, with the majority being found to encode NBS-LRR proteins (11). Plant NBS-LRR proteins can be subdivided into two broad categories defined by the presence of a Toll-interleukin receptor (TIR) domain or a non-TIR domain, most often a coiled-coil (CC) domain, at the amino terminus. The function of the CC and TIR domains in pathogen perception and signaling is un...

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Resistance Genes ( R Genes) in Plants

Hammond‐Kosack¹,

Kanyuka²

2007

Encyclopedia of Life Sciences

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The activation of plant defence to restrict pathogen invasion is often conferred by resistance (R) proteins. The most prevalent class of R proteins contain leucine‐rich repeats (LRRs), a central nucleotide binding site and a variable amino terminal domain. Other classes possess an extracellular LRR domain, a transmembrane domain and sometimes an intracellular serine/threonine kinase domain. R proteins function in pathogen perception and/or the activation of conserved defence signalling networks. Upon infection, specific effectors produced by pathogens and presumed to promote growth in host tissue, are either directly recognized by different R proteins or are recognized by a targeted plant protein which is itself guarded by R proteins. Subsequently, various defence signalling networks are activated via R protein phosphorylation, oligomerization, degradation, conformational changes and by the shuttling of R proteins between the plant cell cytoplasm and the nucleus. The overall outcome is dramatic cellular reprogramming and the activation of coordinated defence responses both locally at the site of infection as well as systemically throughout the plant. Many R gene loci appear to be under positive genetic selection, which rapidly diversifies paralogous sequences. Some R genes are present in plant genomes at single loci as either a single sequence or an allelic series whilst others reside within tight or loose clusters of related R sequences. For a century, plant breeders have genetically characterized and used R genes to reduce the impact of pathogens on crop production. More recently, various transgenic approaches have been tested to provide broader spectrum control and improved durability.

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Elicitor-Mediated Oligomerization of the Tobacco N Disease Resistance Protein

Cited by 236 publications

References 43 publications

Plant NBS-LRR proteins in pathogen sensing and host defense

Plant NBS-LRR proteins in pathogen sensing and host defense

Indirect activation of a plant nucleotide binding site–leucine-rich repeat protein by a bacterial protease

Resistance Genes ( R Genes) in Plants

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