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Type III Effector Protein (type + iii_effector_protein)
Selected AbstractsType III effectors orchestrate a complex interplay between transcriptional networks to modify basal defence responses during pathogenesis and resistanceTHE PLANT JOURNAL, Issue 1 2006William Truman Summary To successfully infect a plant, bacterial pathogens inject a collection of Type III effector proteins (TTEs) directly into the plant cell that function to overcome basal defences and redirect host metabolism for nutrition and growth. We examined (i) the transcriptional dynamics of basal defence responses between Arabidopsis thaliana and Pseudomonas syringae and (ii) how basal defence is subsequently modulated by virulence factors during compatible interactions. A set of 96 genes displaying an early, sustained induction during basal defence was identified. These were also universally co-regulated following other bacterial basal resistance and non-host responses or following elicitor challenges. Eight hundred and eighty genes were conservatively identified as being modulated by TTEs within 12 h post-inoculation (hpi), 20% of which represented transcripts previously induced by the bacteria at 2 hpi. Significant over-representation of co-regulated transcripts encoding leucine rich repeat receptor proteins and protein phosphatases were, respectively, suppressed and induced 12 hpi. These data support a model in which the pathogen avoids detection through diminution of extracellular receptors and attenuation of kinase signalling pathways. Transcripts associated with several metabolic pathways, particularly plastid based primary carbon metabolism, pigment biosynthesis and aromatic amino acid metabolism, were significantly modified by the bacterial challenge at 12 hpi. Superimposed upon this basal response, virulence factors (most likely TTEs) targeted genes involved in phenylpropanoid biosynthesis, consistent with the abrogation of lignin deposition and other wall modifications likely to restrict the passage of nutrients and water to the invading bacteria. In contrast, some pathways associated with stress tolerance are transcriptionally induced at 12 hpi by TTEs. [source] Type III-dependent translocation of the Xanthomonas AvrBs3 protein into the plant cellMOLECULAR MICROBIOLOGY, Issue 1 2002Boris Szurek Summary Many plant pathogenic bacteria utilize a conserved type III secretion system (TTSS) to deliver effector proteins into the host tissue. Indirect evidence has suggested that at least some effector proteins are translocated from the bacterial cytoplasm into the plant cell. Using an immunocytochemical approach, we demonstrate that the type III effector AvrBs3 from Xanthomonas campestris pv. vesicatoria localizes to nuclei of infected pepper leaves. Importantly, AvrBs3 translocation was observed in situ in native tissues of susceptible and resistant plants. AvrBs3 was detected in the nucleus as soon as 4 h post infection, which was dependent on a functional TTSS and the putative translocator HrpF. N-terminal AvrBs3 deletion derivatives are no longer secreted by the TTSS in vitro and could not be detected inside the host cells, suggesting that the N-terminus of AvrBs3 is important for secretion. Deletion of the nuclear localization signals in the AvrBs3 C-terminus, which are required for the AvrBs3-mediated induction of the hypersensitive reaction in resistant pepper plants, abolished AvrBs3 localization to the nucleus. This is the first report on direct evidence for translocation of a native type III effector protein from a plant pathogenic bacterium into the host cell. [source] Crystallization and preliminary crystallographic analysis of the ADP-ribosyltransferase HopU1ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2010Yan Lin Several Gram-negative pathogens of plants and animals and some eukaryotic associated bacteria use type III protein-secretion systems (T3SSs) to deliver bacterial virulence-associated `effector' proteins directly into host cells. HopU1 is a type III effector protein from the plant pathogen Pseudomonas syringae, which causes plant bacterial speck disease. HopU1 quells host immunity through ADP-ribosylation of GRP7 as a substrate. HopU1 has been reported as the first ADP-ribosyltransferase virulence protein to be identified in a plant pathogen. Although several structures of ADP-ribosyltransferases have been determined to date, no structure of an ADP-ribosyltransferase from a plant pathogen has been determined. Here, the protein expression, purification, crystallization and preliminary crystallographic analysis of HopU1 are reported. Diffracting crystals were grown by hanging-drop vapour diffusion using polyethylene glycol 10,000 as a precipitant. Native and SAD data sets were collected using native and selenomethionine-derivative HopU1 crystals. The diffraction pattern of the crystal extended to 2.7,Å resolution using synchrotron radiation. The crystals belonged to space group P43, with unit-cell parameters a = 92.6, b = 92.6, c = 101.6,Å. [source] New effects of type III effectorsMOLECULAR MICROBIOLOGY, Issue 2 2003Roger Innes Summary The enzymatic activities and/or targets of four type III effector proteins from plant pathogens have been reported in a flurry of new papers. In this issue, XopD is shown to remove SUMO groups from host cell proteins, while in previous issues of Molecular Microbiology, HopPtoD2 was shown to function as a tyrosine phosphatase and AvrRpt2 as probably a cysteine protease that targets the host RIN4 protein. Finally, AvrPphB is revealed in a recent Science paper to function as a cysteine protease that targets the host PBS1 kinase. This work is providing some of the first insights into how plant pathogens subvert host cell signalling machinery to cause disease. [source] | ||||||||||