====== XopE1 ======

Author: [[https://www.researchgate.net/profile/Jaime_Cubero|Jaime Cubero]]\\
Internal reviewer: [[https://www.researchgate.net/profile/Ralf_Koebnik|Ralf Koebnik]]\\
Expert reviewer: FIXME

Class: XopE\\
Family: XopE1\\
Prototype: XCV0294 (//Xanthomonas euvesicatoria// pv. //euvesicatoria//, ex //Xanthomonas campestris// pv. //vesicatoria//; strain 85-10)\\
RefSeq ID: [[https://www.ncbi.nlm.nih.gov/protein/CAJ21925.1|CAJ21925.1]] (400 aa)\\
Synonym: AvrXacE1 (//Xanthomonas citri// pv. //citri//)\\
3D structure: Myristoylation motif at the extreme N terminus (Thieme //et al.//, 2007).

===== Biological function =====

=== How discovered? ===

XopE1 was first identified by sequence homology searches (da Silva //et al//., 2002; Thieme //et al//., 2005).
=== (Experimental) evidence for being a T3E ===

XopE1 fused to the AvrBs3 reporter was shown to be secreted into culture supernatants in a //hrcV-//dependent manner (Thieme //et al//., 2007). The same fusion constract was translocated into plant cells in a //hrcV//- and //hrpF//-dependent manner (Thieme //et al//., 2007).
=== Regulation ===

Using RT-PCR analyses, XopE1 from //X. euvesicatoria// was found to be upregulated by HrpG and HrpX (Thieme //et al//., 2007). The promoter of xopE1<sub>XCV85-10</sub> contains a PIP BOX (Thieme //et al//., 2007).

Transcriptome analysis (RNA-seq) and qRT-PCR revealed that //avrXacE1// (//xopE1//) gene expression is downregulated in a //X. citri// pv. //citri// Δ//phoP// mutant, indicating that PhoP is a positive regulator of //xopE1// expression (Wei et al., 2019).
=== Phenotypes ===

//Agrobacterium//-mediated expression of XopE1 triggers a fast cell-death reaction in non host //Nicotiana// plants revealing that XopE1 is recognized by //Nicotiana//. Its membrane localization delays the detection by the plant surveillance system and contributes to inactivate plant immune responses (Thieme //et al//., 2007). XopE1 was associated to different grades of cytotoxicity and intermediate growth inhibition on yeast and caused phenotypes ranging from chlorosis to cell death when transiently expressed via //Agrobacterium// in either host or non-host plants (Salomon //et al//., 2011; Adlung //et al//., 2016). XopE1 mutants grew to equivalent titers as wild-type //X. euvesicatoria// in tomato leaves indicating that is not required for bacterial multiplication in planta. However, XopE1 was found to be required to suppress chlorosis and tissue collapse at very late stages of //Xanthomonas// infection. XopE1 together with XopE2 and XopO may function redundantly to inhibit //X//. //euvesicatoria//-induced chlorosis in tomato leaves (Dubrow //et al//., 2018).
=== Localization ===

XopE1 fused to GFP reporter in a binary vector under control of the Cauliflower mosaic virus 35S promoter and transiently expressed in //Nicotiana benthamiana// leaves, using //Agrobacterium-//mediated gene transfer, allowed to observe XopE1::GFP to be confined to the periphery of the cells and being not detectable in the nucleus or in the cytoplasm.
=== Enzymatic function ===

XopE1 belongs to the HopX effector family, members of which belong to the transglutaminase superfamily (Nimchuk //et al//., 2007).
=== Interaction partners ===

XopE1 was found to physically interact with tomato 14-3-3s (TFT) (Dubrow //et al.//, 2018). In addition, XopE1 was predicted to interact with VirK, which is secreted by the T2SS and for which a possible role in the modulation of plant immune response during the infection process was suggested (Assis //et al//., 2017).
===== Conservation =====

=== In xanthomonads ===

Yes (//e.g.//, //X. alfalfa, X. citri, X. euvesicatoria//, //X. phaseoli//).
=== In other plant pathogens/symbionts ===

Yes (//Acidovorax// spp., //Pseudomonas// spp., //Ralstonia// //solanacearum//; more distant homologs in rhizobia).
===== References =====

Adlung N, Prochaska H, Thieme S, Banik A, Blüher D, John P, Nagel O, Schulze S, Gantner J, Delker C, Stuttmann J, Bonas U (2016). Non-host resistance induced by the //Xanthomonas// effector XopQ is widespread within the genus //Nicotiana// and functionally depends on EDS1. Front. Plant Sci. 7: 1796. DOI: [[https://doi.org/10.3389/fpls.2016.01796|10.3389/fpls.2016.01796]]

Assis RAB, Polloni LC, Patané JSL, Thakur S, Felestrino ÉB, Diaz-Caballero J, Digiampietri LA, Goulart LR, Almeida NF, Nascimento R, Dandekar AM, Zaini PA, Setubal JC, Guttman DS, Moreira LM (2017). Identification and analysis of seven effector protein families with different adaptive and evolutionary histories in plant-associated members of the //Xanthomonadaceae//. Sci. Rep. 7:16133. DOI: [[https://doi.org/10.1038/s41598-017-16325-1|10.1038/s41598-017-16325-1]]

da Silva AC, Ferro JA, Reinach FC, Farah CS, Furlan LR, Quaggio RB, Monteiro-Vitorello CB, Van Sluys MA, Almeida NF, Alves LM, do Amaral AM, Bertolini MC, Camargo LE, Camarotte G, Cannavan F, Cardozo J, Chambergo F, Ciapina LP, Cicarelli RM, Coutinho LL, Cursino-Santos JR, El Dorry H, Faria JB, Ferreira AJ, Ferreira RC, Ferro MI, Formighieri EF, Franco MC, Greggio CC, Gruber A, Katsuyama AM, Kishi LT, Leite RP, Lemos EG, Lemos MV, Locali EC, Machado MA, Madeira AM, Martinez-Rossi NM, Martins EC, Meidanis J, Menck CF, Miyaki CY, Moon DH, Moreira LM, Novo MT, Okura VK, Oliveira, MC, Oliveira VR, Pereira HA, Rossi A, Sena JA, Silva C, de Souza RF, Spinola LA,Takita MA, Tamura RE, Teixeira EC, Tezza RI, Trindade dos SM, Truffi D, Tsai, SM, White FF, Setubal JC, Kitajima JP (2002). Comparison of the genomes of two //Xanthomonas// pathogens with differing host specificities. Nature 417: 459-463. DOI: [[https://doi.org/10.1038/417459a|10.1038/417459a]]

Dubrow Z, Sunitha S, Kim JG, Aakre CD, Girija AM, Sobol G, Teper D, Chen YC, Ozbaki-Yagan N, Vance H, Sessa G, Mudgett MB (2018). Tomato 14-3-3 proteins are required for //Xv3// disease resistance and interact with a subset of //Xanthomonas euvesicatoria// effectors. Mol. Plant Microbe Interact. 31: 1301-1311. DOI: [[https://doi.org/10.1094/MPMI-02-18-0048-R|10.1094/MPMI-02-18-0048-R]]

Nimchuk ZL, Fisher EJ, Desvaux D, Chang JH, Dangl JL (2007). The HopX (AvrPphE) family of //Pseudomonas syringae// type III effectors require a catalytic triad and a novel N-terminal domain forfunction. Mol. Plant Microbe Interact. 20: 346-357. DOI: [[https://doi.org/10.1094/MPMI-20-4-0346|10.1094/MPMI-20-4-0346]]

Salomon D, Dar D, Sreeramulu S, Sessa G (2011). Expression of //Xanthomonas campestris// pv. vesicatoria type III effectors in yeast affects cell growth and viability. Mol Plant Microbe Interact. 24: 305-314. DOI: [[https://doi.org/0.1094/MPMI-09-10-0196|0.1094/MPMI-09-10-0196]]

Thieme F, Koebnik R, Bekel T, Berger C, Boch J, Büttner D, Caldana C, Gaigalat L, Goesmann A, Kay S, Kirchner O, Lanz C, Linke B, McHardy AC, Meyer F, Mittenhuber G, Nies DH, Niesbach-Klösgen U, Patschkowski T, Rückert C, Rupp O, Schneiker S, Schuster SC, Vorhölter F, Weber E, Pühler A, Bonas U, Bartels D, Kaiser O (2005). Insights into genome plasticity and pathogenicity of the plant pathogenic bacterium //Xanthomonas campestris// pv. vesicatoria revealed by the complete genome sequence. J. Bacteriol. 187: 7254-7266. DOI: [[https://doi.org/10.1128/JB.187.21.7254-7266.2005|10.1128/JB.187.21.7254-7266.2005]]

Thieme F, Szczesny R, Urban A, Kirchner O, Hause G, Bonas U (2007). New type III effectors from //Xanthomonas campestris// pv. vesicatoria trigger plant reactions dependent on a conserved N-myristoylation motif. Mol. Plant Microbe Interact. 20: 1250-1261. DOI: [[https://doi.org/10.1094/MPMI-20-10-1250|10.1094/MPMI-20-10-1250]]

Wei C, Ding T, Chang C, Yu C, Li X, Liu Q (2019). Global regulator PhoP is necessary for motility, biofilm formation, exoenzyme production and virulence of //Xanthomonas citri// subsp. //citri// on citrus plants. Genes 10: 340. DOI: [[https://doi.org/10.3390/genes10050340|10.3390/genes10050340]]