====== The Type III Effector XopY from //Xanthomonas// ======

Author: [[https://www.researchgate.net/profile/Irena_Macioniene|Irena Mačionienė]]\\
Internal reviewer: [[https://www.researchgate.net/profile/Lucas_Moriniere|Lucas Morinière]]\\

Class: XopY\\
Family: XopY\\
Prototype: XOO1488 (//Xanthomonas oryzae// pv. //oryzae//; strain T7174)\\
GenBank ID: [[https://www.ncbi.nlm.nih.gov/protein/BAE68243.1|BAE68243.1]] (281 aa)\\
RefSeq ID: [[https://www.ncbi.nlm.nih.gov/protein/WP_011408080.1|WP_011408080.1]] (281 aa)\\
3D structure: Unknown

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

=== How discovered? ===

XopY was discovered by screening the genome of //X. oryzae// pv. //oryzae// (//Xoo//) strain MAFF 311018 for proteins displaying a N-terminal amino acid pattern associated with T3S substrates in //Pseudomonas syringae// (Furutani //et al.//, 2009). It has been primarily referred to as XOO1488, and then XopY (Song & Yang, 2010).
=== (Experimental) evidence for being a T3E ===

//Xoo //transformants containing a plasmidic fusion of XopY (= XOO1488) with the Cya translocation reporter system were inoculated in tomato leaves. An increase of cAMP in the inflitrated areas was observed, thus revealing translocation of the fused protein into plant cells (Furutani //et al.//, 2009).
=== Regulation ===

The //xopY// <sub> </sub> gene of //Xoo// contains a PIP box and ‐10 motif in the promoter region (TTCGB‐N<sub>15</sub> ‐TTCGB‐N<sub>30–32</sub> ‐YANNNT) (Yamaguchi //et al//., 2013a). Also, it was shown to be regulated by HrpX (Furutani //et al.//, 2009).

qRT-PCR revealed that transcript levels of 15 out of 18 tested non-TAL effector genes (as well as the regulatory genes //hrpG// and //hrpX//), including //xopY//, were significantly reduced in the //Xoo// Δ//xrvC// mutant compared with those in the wild-type strain PXO99<sup>A</sup>  (Liu //et al.//, 2016).
=== Phenotypes ===

  * XopY of //Xoo//  was shown to inhibit peptidoglycan- and chitin-induced expression of defense-related genes (Yamaguchi //et al.//, 2013).
  * XopY of //X. oryzae//  pv. //oryzicola//  (//Xoc//) was also shown to trigger HR in non-host //Nicotiana benthamiana//  plants (Li //et al.//, 2015).
  * XopY was shown to suppresses the activation of OsMAPKKK24 by enhancing its intramolecular interaction between the N‐ and C‐terminal regions. The association of XopY with OsRLCK55 and OsMAPKKK24 was also shown to interfere with their interaction and to suppress OsRLCK55‐mediated transphosphorylation of OsMAPKKK24, ultimately inhibiting MAPK activation and subsequent disease resistance (Chen //et al.//, 2026).

=== Localization ===

Unknown.

=== Enzymatic function ===

Unknown.

=== Interaction partners ===

XopY from the //Xoo//  strain MAFF 3110018 was demonstrated to target OsRLCK185. Expression of XopY in rice cells compromises OsRLCK185-mediated immune responses, which is consistent with the fact that Xoo1488 inhibits trans-phosphorylation of the activation domain of OsRLCK185 by OsCERK1. Interestingly, XopY is phosphorylated by OsRLCK185, suggesting that modification of XopY in host cell may affect their virulent activity (Yamaguchi //et al//., 2013).

XopY from the //Xoo//  strain PXO86 was shown to interact with the MAPK kinase kinase OsMAPKKK24 and with the RECEPTOR‐LIKE CYTOPLASMIC KINASE 55 (OsRLCK55) (Chen //et al.//, 2026).

===== Conservation =====

=== In xanthomonads ===

Yes (//e.g.//, //X. oryzae//, //X. translucens, X. vasicola//).

=== In other plant pathogens/symbionts ===

No.

===== References =====

Chen L, Chen Y, Xu W, Wu X, Deng S, Wang Z, Tang D, Wang W (2026). Disruption of OsMAPKKK24 activation by the //Xanthomonas oryzae// effector XopY leads to compromised disease resistance in rice. J. Integr. Plant Biol., in press. DOI: [[https://doi.org/10.1111/jipb.70428|10.1111/jipb.70428]]

Furutani A, Takaoka M, Sanada H, Noguchi Y, Oku T, Tsuno K, Ochiai H, Tsuge S (2009). Identification of novel type III secretion effectors in //Xanthomonas oryzae// pv. //oryzae//. Mol. Plant Microbe Interact. 22: 96-106. DOI: [[https://doi.org/10.1094/MPMI-22-1-0096|10.1094/MPMI-22-1-0096]]

Li S, Wang Y, Wang S, Fang A, Wang J, Liu L, Zhang K, Mao Y, Sun W (2015). The type III effector AvrBs2 in //Xanthomonas oryzae// pv. //oryzicola// suppresses rice immunity and promotes disease development. Mol. Plant Microbe Interact. 28: 869-880. DOI: [[https://doi.org/10.1094/MPMI-10-14-0314-R|10.1094/MPMI-10-14-0314-R]]

Liu Y, Long J, Shen D, Song C (2016). //Xanthomonas oryzae// pv. //oryzae// requires H-NS-family protein XrvC to regulate virulence during rice infection. FEMS Microbiol. Lett. 363: fnw067. DOI: [[https://doi.org/10.1093/femsle/fnw067|10.1093/femsle/fnw067]]

Song C, Yang B (2010). Mutagenesis of 18 type III effectors reveals virulence function of XopZ<sub>PXO99</sub> in //Xanthomonas oryzae// pv. //oryzae//. Mol. Plant Microbe Interact. 23: 893-902. DOI: [[https://doi.org/10.1094/MPMI-23-7-0893|10.1094/MPMI-23-7-0893]]

Yamaguchi K, Yamada K, Ishikawa K, Yoshimura S, Hayashi N, Uchihashi K, Ishihama N, Kishi-Kaboshi M, Takahashi A, Tsuge S, Ochiai H, Tada Y, Shimamoto K, Yoshioka H, Kawasaki T (2013). A receptor-like cytoplasmic kinase targeted by a plant pathogen effector is directly phosphorylated by the chitin receptor and mediates rice immunity. Cell Host Microbe 13: 347-357. DOI: [[https://doi.org/10.1016/j.chom.2013.02.007|10.1016/j.chom.2013.02.007]]

===== Acknowledgements =====

This fact sheet is based upon work from COST Action CA16107 EuroXanth, supported by COST (European Cooperation in Science and Technology).