38 research outputs found
Genetic and molecular requirements for function of the Pto/Prf effector recognition complex in tomato and Nicotiana benthamiana
No full textThe Pto gene of tomato (Solanum lycopersicum) confers specific recognition of the unrelated bacterial effector proteins AvrPto and AvrPtoB. Pto resides in a constitutive molecular complex with the nucleotide binding site-leucine rich repeats protein Prf
The tomato Prf complex is a molecular trap for bacterial effectors based on Pto transphosphorylation
No full textThe bacteria Pseudomonas syringae is a pathogen of many crop species and one of the model pathogens for studying plant and bacterial arms race coevolution. In the current model, plants perceive bacteria pathogens via plasma membrane receptors, and recognition leads to the activation of general defenses. In turn, bacteria inject proteins called effectors into the plant cell to prevent the activation of immune responses. AvrPto and AvrPtoB are two such proteins that inhibit multiple plant kinases. The tomato plant has reacted to these effectors by the evolution of a cytoplasmic resistance complex. This complex is compromised of two proteins, Prf and Pto kinase, and is capable of recognizing the effector proteins. How the Pto kinase is able to avoid inhibition by the effector proteins is currently unknown. Our data shows how the tomato plant utilizes dimerization of resistance proteins to gain advantage over the faster evolving bacterial pathogen. Here we illustrate that oligomerisation of Prf brings into proximity two Pto kinases allowing them to avoid inhibition by the effectors by transphosphorylation and to activate immune responses
Mapping daily evapotranspiration at field to continental scales using geostationary and polar orbiting satellite imagery
No full textThermal infrared (TIR) remote sensing of land-surface temperature (LST) provides valuable information about the sub-surface moisture status required for estimating evapotranspiration (ET) and detecting the onset and severity of drought. While empirical indices measuring anomalies in LST and vegetation amount (e.g., as quantified by the Normalized Difference Vegetation Index; NDVI) have demonstrated utility in monitoring ET and drought conditions over large areas, they may provide ambiguous results when other factors (e.g., air temperature, advection) are affecting plant functioning. A more physically based interpretation of LST and NDVI and their relationship to sub-surface moisture conditions can be obtained with a surface energy balance model driven by TIR remote sensing. The Atmosphere-Land Exchange Inverse (ALEXI) model is a multi-sensor TIR approach to ET mapping, coupling a two-source (soil + canopy) land-surface model with an atmospheric boundary layer model in time-differencing mode to routinely and robustly map daily fluxes at continental scales and 5 to 10-km resolution using thermal band imagery and insolation estimates from geostationary satellites. A related algorithm (DisALEXI) spatially disaggregates ALEXI fluxes down to finer spatial scales using moderate resolution TIR imagery from polar orbiting satellites. An overview of this modeling approach is presented, along with strategies for fusing information from multiple satellite platforms and wavebands to map daily ET down to resolutions on the order of 10 m. The ALEXI/DisALEXI model has potential for global applications by integrating data from multiple geostationary meteorological satellite systems, such as the US Geostationary Operational Environmental Satellites, the European Meteosat satellites, the Chinese Fen-yung 2B series, and the Japanese Geostationary Meteorological Satellites. Work is underway to further evaluate multi-scale ALEXI implementations over the US, Europe, Africa and other continents with geostationary satellite coverage. © Author(s) 2011
Identification of post-translational modifications of plant protein complexes
No full textPlants adapt quickly to changing environments due to elaborate perception and signaling systems. During pathogen attack, plants rapidly respond to infection via the recruitment and activation of immune complexes. Activation of immune complexes is associated with post-translational modifications (PTMs) of proteins, such as phosphorylation, glycosylation, or ubiquitination. Understanding how these PTMs are choreographed will lead to a better understanding of how resistance is achieved. Here we describe a protein purification method for nucleotide-binding leucine-rich repeat (NB-LRR)-interacting proteins and the subsequent identification of their post-translational modifications (PTMs). With small modifications, the protocol can be applied for the purification of other plant protein complexes. The method is based on the expression of an epitope-tagged version of the protein of interest, which is subsequently partially purified by immunoprecipitation and subjected to mass spectrometry for identification of interacting proteins and PTMs. This protocol demonstrates that: i). Dynamic changes in PTMs such as phosphorylation can be detected by mass spectrometry; ii). It is important to have sufficient quantities of the protein of interest, and this can compensate for the lack of purity of the immunoprecipitate; iii). In order to detect PTMs of a protein of interest, this protein has to be immunoprecipitated to get a sufficient quantity of protein
Regulation of Tomato Prf by Pto-like Protein Kinases
No full textTomato Prf encodes a nucleotide-binding domain shared by Apaf-1, certain R proteins, and CED-4 fused to C-terminal leucine-rich repeats (NBARC-LRR) protein that is required for bacterial immunity to Pseudomonas syringae and sensitivity to the organophosphate fenthion. The signaling pathways involve two highly related protein kinases. Pto kinase mediates direct recognition of the bacterial effector proteins AvrPto or AvrPtoB. Fen kinase is required for fenthion sensitivity and recognition of bacterial effectors related to AvrPtoB. The role of Pto and its association with Prf has been characterized but Fen is poorly described. We show that, similar to Pto, Fen requires N-myristoylation and kinase activity for signaling and interacts with the N- terminal domain of Prf. Thus, the mechanisms of activation of Prf by the respective protein kinases are similar. Prf-Fen interaction is underlined by coregulatory mechanisms in which Prf negatively regulates Fen, most likely by controlling kinase activity. We further characterized negative regulation of Prf by Pto, and show that regulation is mediated by the previously described negative regulatory patch. Remarkably, the effectors released negative regulation of Prf in a manner dependent on Pto kinase activity. The data suggest a model in which Prf associates generally with Pto-like kinases in tightly regulated complexes, which are activated by effector-mediated disruption of negative regulation. Release of negative regulation may be a general feature of activation of NBARC-LRR proteins by cognate effectors
Το σαξόφωνο στην συμφωνική μουσική του 19ου αιώνα
No full textΤο σαξόφωνο απο την αρχή της εφεύρεσής του το 1846, παρόλο που ήταν ένα μουσικό όργανο με ιδιαίτερο και ευέλικτο ηχόχρωμα, δεν κατάφερε να γίνει ένα απο τα πιο διαδεδομένα όργανα της συμφωνικής μουσικής , όπως άλλα που δέσποζαν σε εκείνη την περίοδο. ο προβληματισμός που δημιουργήθηκε έυλογα ήταν γιατί ένα τέτοιο όργανο δεν ενσωματώθηκε απευθείας μέσα στην συμφωνική ορχήστρα. Απο τη μία υποστηρίζεται πως δημιουργήθηκε σε έναν αιώνα όπου η συμφωνική ορχήστρα είχε ήδη σταθεροποιηθεί και ήταν παρακινδυνευμένο να διαταραχθεί η ισορροπία στις συνθέσεις, συνεπάγοντας έτσι την περιθωριοποίησή του. Απο την άλλη όμως, έχει αποδειχθεί οτι ο Adolphe Sax, ο δημιουργός του σαξόφωνου, είχε πολλούς εχθρούς που προπαγάνδισαν την ηθελημένη αποτυχία του ίδιου του δημιουργού και κατα συνέπεια του σαξόφωνου. Σκοπός αυτής της εργασίας είναι μέσα απο γεγονότα και καταστάσεις να αναφερθεί η πορεία που ακολούθησε το σαξόφωνο, οι συνθέτες που επέλεξαν και υποστήριξαν την ένταξή του στην συμφωνική μουσική απο την αρχή της δημιουργίας του μέχρι και τις αρχές του 20ου αιώνα, και να αναζητηθούν ιδιαιτερότητες, συνθετικές και εκτελεστικές, μέσα απο τρία παραδείγματα συμφωνικής μουσικής: 1. Pictures at an exhibition: The old castle, M. Mussorgsky (1874) 2. L'Arlesienne suite no.2, Pastorale, G.Bizet (1880) 3. Rapsodie for saxophone and orchestra, C.Debussy (1903)The saxophone since the beginning of its invention in 1846, although it was a musical instrument with a distinctive and versatile sound, failed to become one of the most widespread organs of symphonic music, such as those that dominated at that era. The question that was created was why such an instrument was not directly incorporated into the symphony orchestra. On the one hand it is argued that it was created in a century when the symphony orchestra had already stabilized and was in danger of disturbing the balance in the compositions, thus implying its marginalization. On the other hand, it has been shown that Adolphe Sax, the saxophone creator, had many enemies that propagated the deliberate failure of the author himself and consequently the saxophone. The purpose of this thesis is through events and situations to refer to the course that the saxophone followed the composers who chose and supported their integration into symphonic music from the beginning of its creation until the beginning of the 20th century and to analyze composing, performing issues, through three examples of symphonic music: 1. Pictures at an exhibition: The old castle, M. Mussorgsky (1874) 2. L'Arlesienne suite no.2, Pastorale, G.Bizet (1880) 3. Rhapsody for saxophone and orchestra, C.Debussy (1903
Gene gain and loss during evolution of obligate parasitism in the white rust pathogen of Arabidopsis thaliana
No full textBiotrophic eukaryotic plant pathogens require a living host for their growth and form an intimate haustorial interface with parasitized cells. Evolution to biotrophy occurred independently in fungal rusts and powdery mildews, and in oomycete white rusts and downy mildews. Biotroph evolution and molecular mechanisms of biotrophy are poorly understood. It has been proposed, but not shown, that obligate biotrophy results from (i) reduced selection for maintenance of biosynthetic pathways and (ii) gain of mechanisms to evade host recognition or suppress host defence. Here we use Illumina sequencing to define the genome, transcriptome, and gene models for the obligate biotroph oomycete and Arabidopsis parasite, Albugo laibachii. A. laibachii is a member of the Chromalveolata, which incorporates Heterokonts (containing the oomycetes), Apicomplexa (which includes human parasites like Plasmodium falciparum and Toxoplasma gondii), and four other taxa.
From comparisons with other oomycete plant pathogens and other chromalveolates, we reveal independent loss of
molybdenum-cofactor-requiring enzymes in downy mildews, white rusts, and the malaria parasite P. falciparum. Biotrophy also requires ‘‘effectors’’ to suppress host defence; we reveal RXLR and Crinkler effectors shared with other oomycetes, and also discover and verify a novel class of effectors, the ‘‘CHXCs’’, by showing effector delivery and effector functionality. Our findings suggest that evolution to progressively more intimate association between host and parasite results in reduced selection for retention of certain biosynthetic pathways, and particularly reduced selection for retention of molybdopterinrequiring
biosynthetic pathways. These mechanisms are not only relevant to plant pathogenic oomycetes but also to
human pathogens within the Chromalveolata
PESI - a taxonomic backbone for Europe
No full textThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The attached file is the published version of the article.NHM Repositor
Prf immune complexes of tomato are oligomeric and contain multiple Pto-like kinases that diversify effector recognition
No full textCytoplasmic recognition of pathogen virulence effectors by plant NB-LRR proteins leads to strong induction of defence responses termed effector triggered immunity (ETI). In tomato, a protein complex containing the NB-LRR protein Prf and the protein kinase Pto confers recognition of the Pseudomonas syringae effectors AvrPto and AvrPtoB. Although structurally unrelated, AvrPto and AvrPtoB interact with similar residues in the Pto catalytic cleft to activate ETI via an unknown mechanism. Here we show that the Prf complex is oligomeric, containing at least two molecules of Prf. Within the complex, Prf can associate with Pto or one of several Pto family members including Fen, Pth2, Pth3, or Pth5. The dimerization surface for Prf is the novel N-terminal domain, which also coordinates an intramolecular interaction with the remainder of the molecule, and binds Pto kinase or a family member. Thus, association of two Prf N-terminal domains brings the associated kinases into close promixity. Tomato lines containing Prf complexed with Pth proteins but not Pto possessed greater immunity against P. syringae than tomatoes lacking Prf. This demonstrates that incorporation of non-Pto kinases into the Prf complex extends the number of effector proteins that can be recognized
Prf immune complexes of tomato are oligomeric and contain multiple Pto-like kinases that diversify effector recognition
No full textCytoplasmic recognition of pathogen virulence effectors by plant NB-LRR proteins leads to strong induction of defence responses termed effector triggered immunity (ETI). In tomato, a protein complex containing the NB-LRR protein Prf and the protein kinase Pto confers recognition of the Pseudomonas syringae effectors AvrPto and AvrPtoB. Although structurally unrelated, AvrPto and AvrPtoB interact with similar residues in the Pto catalytic cleft to activate ETI via an unknown mechanism. Here we show that the Prf complex is oligomeric, containing at least two molecules of Prf. Within the complex, Prf can associate with Pto or one of several Pto family members including Fen, Pth2, Pth3, or Pth5. The dimerization surface for Prf is the novel N-terminal domain, which also coordinates an intramolecular interaction with the remainder of the molecule, and binds Pto kinase or a family member. Thus, association of two Prf N-terminal domains brings the associated kinases into close promixity. Tomato lines containing Prf complexed with Pth proteins but not Pto possessed greater immunity against P. syringae than tomatoes lacking Prf. This demonstrates that incorporation of non-Pto kinases into the Prf complex extends the number of effector proteins that can be recognized
