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bacteria:t3e:xopi [2020/06/30 22:06] irodrigues [Biological function] |
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- | ====== XopI ====== | ||
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- | Author: Trainees from the EuroXanth 2< | ||
- | Internal reviewer: Isabel Rodrigues\\ | ||
- | Expert reviewer: FIXME | ||
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- | Class: XopI\\ | ||
- | Family: Xop\\ | ||
- | Prototype: (// | ||
- | RefSeq ID: [[https:// | ||
- | 3D structure: | ||
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- | ===== Biological function ===== | ||
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- | === How discovered? === | ||
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- | Effector proteins (T3Es) can suppress the plant innate immunity and alter the plant metabolism to the pathogen’s advantage. The T3E XopI was identified in Xcv strain 85-10 due to a F-box motif based on the presence of a PIP (pathogen-inducible promoter) box in its promoter region. XopI secretion and translocation was shown during the interaction of Xcv with resistant pepper plants (Schulze //et al//., 2012). Moreover, interaction studies in yeast showed that XopI specifically interacts with one out of 21 // | ||
- | === (Experimental) evidence for being a T3E === | ||
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- | The transcripts of XopI were amplified from Xcv derivative 85* strain, which expresses a constitutively active HrpG point mutant resulting in constitutive expression of the T3S system, suggesting co‐expression with T3S genes (Schulze //et al//., 2012). To investigate whether //xopI// was indeed T3SS dependently secreted and translocated into the plant cell, a translational fusion with the reporter protein AvrBs3D2, a derivative of the TAL effector AvrBs3 which lacks a T3S and translocation signal, was performed. Fusion of a functional T3S signal to AvrBs3D2 enables its translocation and thus the induction of the HR in pepper cultivar ECW-30R plants that harbor the corresponding resistance gene Bs3. When the bacteria were incubated in T3S medium, XopI1–140-AvrBs3D2 was detected in the culture supernatant of strain 85*, but not of 85*DhrcV, by an AvrBs3-specific antibody. These results demonstrate that the XopI effector contained functional T3S signals in the N-terminal regions (Schulze //et al//., 2012) To test for T3SS dependent translocation, | ||
- | === Regulation === | ||
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- | //XopI// is presumably controlled by both HrpG and HrpX. The HrpX-dependent induction of //xopR// has been described previously (Koebnik //et al.//, 2006). HrpG‐ and HrpX‐dependent co‐regulation with the T3S system (+, co‐regulation; | ||
- | === Phenotypes === | ||
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- | Bacterial strains carrying deletions of //xopI// showed no difference in the induction of disease symptoms and the HR compared with wild-type strain 85-10 (Schulze //et al//., 2012). In tomato plants, virulence of xopI knockout strains is dramatically reduced. The stomatal aperture is as well reduced, suggesting that XopI is essential for Xcv entry into the host plant apoplast | ||
- | === Localization === | ||
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- | According to Büttner //et al.// (2006)), XopI is translocated by the 85*Δ// | ||
- | === Enzymatic function === | ||
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- | These phenotypes can be ascribed either to the virulence activity of the effectors in plant cells, or to their recognition by the plant surveillance system. As shown in [[https:// | ||
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- | === Interaction partners === | ||
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- | XopR and XopS belong to //Xcv// translocation class A, comprising T3Es whose translocation into plant cells is completely dependent on HpaB, whereas XopB, XopG, XopI, XopK, XopM and XopV were assigned to class B, because they are still translocated in the absence of HpaB (Büttner //et al.//, 2006). Both new class A effectors lack homology to known proteins or motifs, so that their molecular function remains elusive. By contrast, the class B effectors comprise the putative enzyme XopG, a member of the HopH family (Lindeberg //et al.//, 2005) of putative zinc metalloproteases. Other effectors possess interesting features, for example XopI contains an F‐box motif typical for eukaryotic proteins playing a role in the ubiquitin‐26S proteasome system (UPS). The UPS controls protein stability in eukaryotes (Willems //et al.//, 2004) and appears to be a favorable target for many T3Es, for example members of the GALA family, which strongly contribute to the virulence of //R. solanacearum// | ||
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- | ===== Conservation ===== | ||
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- | === In xanthomonads === | ||
- | Yes. | ||
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- | === In other plant pathogens/ | ||
- | No. | ||
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- | ===== References ===== | ||
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- | Nagel O, Bonas U (2018). The // | ||
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- | Salomon D, Dar D, Sreeramulu S, Sessa G (2011). Expression of // | ||
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- | Schulze S, Kay S, Büttner D, Egler M, Eschen-Lippold L, Hause G, Krüger A, Lee J, Müller O, Scheel D, Szczesny R, Thieme F, Bonas U (2012). Analysis of new type III effectors from // | ||
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- | Teper D, Sunitha S, Martin GB, Sessa G (2015). Five // | ||
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- | Üstün S, Börnke F (2014). Interactions of // | ||