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Current Opin Plant Biol: How to build a pathogen detector: structural basis of NB-LRR function (2012)

Current Opin Plant Biol: How to build a pathogen detector: structural basis of NB-LRR function (2012) | immunity | Scoop.it

Many plant disease resistance (R) proteins belong to the family of nucleotide-binding-leucine rich repeat (NB-LRR) proteins. NB-LRRs mediate recognition of pathogen-derived effector molecules and subsequently activate host defence. Their multi-domain structure allows these pathogen detectors to simultaneously act as sensor, switch and response factor. Structure–function analyses and the recent elucidation of the 3D structures of subdomains have provided new insight in how these different functions are combined and what the contribution is of the individual subdomains. Besides interdomain contacts, interactions with chaperones, the proteasome and effector baits are required to keep NB-LRRs in a signalling-competent, yet auto-inhibited state. In this review we explore operational models of NB-LRR functioning based on recent advances in understanding their structure.

 

► The N-terminal CC and TIR domain of Mla1 and L6 form homo dimers that are required and sufficient to induce cell death. ► Steady-state levels of signalling-competent NB-LRR R proteins are co-regulated by chaperones and the proteasome. ► NB-LRR activation is a multistep process requiring fine-tuned intramolecular interactions between co-evolved subdomains. ► 3D modelling of NB-LRR structures aids predicting the conformational changes underlying R protein function and activity. ► Changes in the conformational fold of NB-LRR R proteins correlate with distinct subcellular localisations.


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Meet the instructors: Frank Takken, University of Amsterdam

Meet the instructors: Frank Takken, University of Amsterdam | immunity | Scoop.it

I am interested in the molecular mechanisms of gene-for-gene based resistance in plants and strategies employed by pathogens to overcome disease resistance. Resistance (R) proteins recognize specific pathogens and trigger activation of signal transduction cascades that induce defense responses that restrict pathogen ingress. My major research questions are: A) how does a plant recognize a pathogen, B) how is defense signaling activated and what is the role of post-translation modifications in this process and C) how does a pathogen avoid or suppress defense responses?
Our main model is the interaction between tomato and the soil-borne fungal pathogen Fusarium oxysporum fsp. lycopersici (see figure 1). Fusarium colonizes the xylem vessels of a plant causing wilt disease. During infectionthe fungus secretes many small proteinsinthe xylem sap that are referred to as SIX protein (secreted in xylem). In our current projects we are studying the role of these proteins for the fungus and the role they have in the infection process. For instance Six3 (Avr2) was found to be required for full virulence on susceptible plants. Currently we are investigating the ability of SIX proteins to interfere with the induction of host defense.

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Meet the instructors: Bart Thomma, Laboratory of Phytopathology, Wageningen University

Meet the instructors: Bart Thomma, Laboratory of Phytopathology, Wageningen University | immunity | Scoop.it

I am interested in fungal pathogenicity mechanisms, in particular of the vascular wilt fungus Verticillium dahliae. This fungus infects a wide range of host plants that includes numerous crops, ornamentals and trees. The research in my lab focuses on the biology, genomics and pathology of Verticillium dahliae and resistance against this pathogen in tomato mediated by the receptor-like protein Ve1. Interestingly, interfamily transfer of tomato Ve1 mediates Verticillium resistance in Arabidopsis.


In plant pathology, it is broadly accepted that successful pathogens secrete so-called “effectors” to perturb or suppress host defenses. Typically, pathogen effector catalogs are lineage-specific and effectors lack homologs in other species. We recently identified the LysM effector Ecp6 in the fungal tomato pathogen Cladosporium fulvum that perturbs host immunity by acting as a stealth factor. Intriguingly, LysM effectors occur throughout the fungal kingdom and I am interested to study the role of LysM effectors in fungal biology.

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Heterobasidion annosum

Heterobasidion annosum | immunity | Scoop.it

Heterobasidion annosum is a basidiomycete fungus in the family Bondarzewiaceae. It is considered to be the most economically important forest pathogen in the Northern Hemisphere. Heterobasidion annosum is widespread in forests in the United States and is responsible for the loss of one billion U.S. dollars annually. This fungus has been known by many different names. Commonly, it is also known as annosum root rot. First described by Fries in 1821, it was known by the name Polyporus annosum. Later, it was found to be linked to conifer disease by Hartig in 1874, and was renamed Fomes annosus by H. Karsten. Its current name of Heterobasion annosum was given by Brefeld in 1888. Heterobasidion annosum is one of the most destructive diseases of conifers.

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Meet the instructors: Cyril Zipfel, The Sainsbury Laboratory

Meet the instructors: Cyril Zipfel, The Sainsbury Laboratory | immunity | Scoop.it

We are using a combination of forward- and reverse-genetics, as well as biochemical and proteomic approaches to answer the main questions underlying our research programme:

 

How are pamp perceived?

What are the signalling events downstream of pamp perception?

What is the contribution of pamp perception to plant immunity?

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Frank Takken's lab: 3D structure of the NB-ARC domain

Frank Takken's lab: 3D structure of the NB-ARC domain | immunity | Scoop.it

Computationally derived 3D structure model of the NB-ARC domain of the resistance protein I-2. The model was created using the ADP bound structure of human APAF-1 (PDB code 1z6t, chain A) as template. Locations of R protein specific motifs are marked with arrows. Amino acids of the MHD motif as well as the sensor I arginine are shown in stick representation. ADP atoms are depicted as balls-and-sticks. Subdomain coloring is: NB: red, ARC1: green, ARC2: blue. Atom coloring is: oxygen: red, nitrogen: blue, phosphorus: orange.
(Figure adapted from van Ooijen et al, (2008) J. Exp. Bot, 59 (6):1383-1397)

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Verticillium research at the Laboratory of Phytopathology, Wageningen University

Verticillium research at the Laboratory of Phytopathology, Wageningen University | immunity | Scoop.it

Verticillium spp. are soil-borne plant pathogens that cause vascular wilt diseases in many economically important crops. Verticillium wilt diseases are difficult to control due to the long viability of the resting structures, the broad host range of the pathogens, and the inability of fungicides to eliminate the pathogens once they have entered the xylem tissues of the plant. In our research we employ tomato (Solanum lycopersicum), Australian tobacco (Nicotiana benthamiana) and thale cress (Arabidopsis thaliana) as model plants to investigate the biology of Verticillium wilt diseases.

 

Here is a Verticillium pathogen profile for more information on the pathogen http://www.php.wur.nl/NR/rdonlyres/0C39DFED-E598-43CD-9490-482FEAB6F582/70434/2006FradinMPP.pdf

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Meet the instructors: Thorsten Nürnberger, ZMBP - Center for Plant Molecular Biology Plant Biochemistry University of Tübingen

Meet the instructors: Thorsten Nürnberger, ZMBP - Center for Plant Molecular Biology Plant Biochemistry University of Tübingen | immunity | Scoop.it

Pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) to microbial infection constitutes an evolutionarily ancient type of immunity that is characteristic of all multicellular eukaryotic systems. Microbial patterns activating plant PTI comprise bacterial flagellin, lipopolypolysaccharides, peptidoglycans or oomycete or fungus-derived proteins, peptides or glucan and chitin oligomers. Plant pattern recognition receptors mediate microbial pattern sensing and subsequent immune activation (Fig.1).

 

Our research aims at a deeper molecular understanding of microbial pattern recognition in plant immunity. In particular, we work on the identification of novel microbial patterns and their corresponding plant pattern recognition receptors. We further study the molecular basis of damage-associated immune activation in plants.

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Meet the instructors: Jonathan Jones, The Sainsbury Laboratory

Meet the instructors: Jonathan Jones, The Sainsbury Laboratory | immunity | Scoop.it

A senior scientist at The Sainsbury Laboratory in Norwich using molecular and genetic approaches to study disease resistance in plants.

 

Received his Ph.d from Cambridge University in 1980, under the direction of G Dover and R B Flavell, and conducted postdoctoral work at Harvard. Head of Sainsbury Laboratory 1994-7, 2003- present, and Professor at University of East Anglia 1997- . He has been editor of Plant Cell and Genome Biology.

 

International Society of Plant Molecular Biology board member 1995-8; Plant Journal advisory board; 1995-8 editor of Plant Cell July; 1998 -2004 Current Opinion in Plant Biology (COPB) editorial board; 1997- present invited editor for COPB Plant/Microbe Interaction Issue; 1998 editor of Genome Biology 2001-2004 reviewing manuscripts and grant proposals. 2007- present: EPSO board member. 2003 elected FRS.

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This page is in support of the EMBO Course "Plant-Microbe Interaction" held in Norwich, June 2012

This page is in support of the EMBO Course "Plant-Microbe Interaction" held in Norwich, June 2012 | immunity | Scoop.it

The last 20 years have provided a sophisticated understanding of how plants recognize relatively conserved microbial patterns to activate defence. This workshop will cover broad aspects of the plant-microbe interaction and train methods to study and visualise intracellular interactions during pathogenesis and defence.

 

Organized by The Sainsbury Laboratory http://www.tsl.ac.uk/


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