====== XopO ======

Author: Harrold van den Burg\\
Internal reviewer: [[https://www.researchgate.net/profile/Jakub_Pecenka|Jakub Pečenka]]\\
Expert reviewer: Zoe Dubrow

Class: XopO\\
Family: XopO\\
Prototype: XopO (//Xanthomonas euvesicatoria// pv. //euvesicatoria//, ex //Xanthomonas campestris// pv. //vesicatoria//; strain 85-10)\\
RefSeq ID: [[https://www.ncbi.nlm.nih.gov/ipg/3884105|AAV74207.1]] (220 aa)\\
3D structure: Unknown

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

=== How discovered? ===

XopO was identified in a genetic screen, using a Tn//5//-based transposon construct harboring the coding sequence for the HR-inducing domain of AvrBs2, but devoid of the effectors' T3SS signal, that was randomly inserted into the genome of //X. campestris// pv. //vesicatoria// (//Xcv//)strain 85-10. The XopO::AvrBs2 fusion protein triggered a //Bs2//-dependent hypersensitive response (HR) in pepper leaves (Roden //et al//., 2004).
=== (Experimental) evidence for being a T3E ===

Type III-dependent secretion was confirmed using a calmodulin-dependent adenylate cyclase reporter assay, with a Δ//hrpF// mutant strain serving as negative control (Roden //et al.//, 2004).
=== Regulation ===

XopO was found to be regulated by HrpG using HrpG* (Roden //et al//., 2004). //XopO// contains a PIP box sequence 31bp upstream of the -10 promoter motif (Koebnik //et al//., 2006).
=== Phenotypes ===

  * Roden et al. did not find significant growth defects of a //Xcv//  Δ//xopO//  mutant in susceptible pepper and tomato leaves (Roden et al., 2004).
  * XopO from //Xcv//  85-10 inhibits cell death in //N. benthamiana//  (Teper //et al//., 2015).
  * XopO suppresses //X. euvesicatoria-//induced chlorosis in leaves of susceptible tomato (Teper //et al//., 2015).
  * XopO failed to inhibit expression of the reporter gene //FRK1//  in response to application of a PAMP, i.e. flg22 peptide (Popov //et al//., 2016).
  * Based on whole genome sequences of //X. euvesicatoria//  strains, it was concluded that the //xopO//  gene has suffered from mutational inactivation by at least four different events, suggesting that selection pressure favors loss of //xopO//  function in this pathogen (Barak //et al//., 2016).

=== Localization ===

Unknown.

=== Enzymatic function ===

Unknown.

=== Interaction partners ===

XopO was shown to interact with tomato 14-3-3 (TFT) proteins (Dubrow //et al//., 2018).

===== Conservation =====

=== In xanthomonads ===

Yes, in some xanthomonads (//e.g.//, //X. euvesicatoria//, //X. oryzae//) (Lang //et al//., 2019). X//opO// is a differential T3E gene between //Xoo//  and //Xoc//  (Hajri //et al//., 2012).

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

Yes, //e.g.// homologs (AvrRps4 and HopK1) in //Pseudomonas syringae//  (Li //et al//., 2014).

===== References =====

Barak JD, Vancheva T, Lefeuvre P, Jones JB, Timilsina S, Minsavage GV, Vallad GE, Koebnik R (2016) Whole-genome sequences of //Xanthomonas euvesicatoria//  strains clarify taxonomy and reveal a stepwise erosion of type 3 effectors. Front Plant Sci. 7: 1805. DOI: [[https://doi.org/10.3389/fpls.2016.01805|10.3389/fpls.2016.01805]]

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]]

Hajri A, Brin C, Zhao S, David P, Feng JX, Koebnik R, Szurek B, Verdier V, Boureau T, Poussier S (2012). Multilocus sequence analysis and type III effector repertoire mining provide new insights into the evolutionary history and virulence of //Xanthomonas oryzae//. Mol. Plant Pathol. 13: 288-302. DOI: [[https://doi.org/10.1111/j.1364-3703.2011.00745.x|10.1111/j.1364-3703.2011.00745.x]]

Koebnik R, Krüger A, Thieme F, Urban A, Bonas U (2006). Specific binding of the Xanthomonas campestris pv. vesicatoria AraC-type transcriptional activator HrpX to plant-inducible promoter boxes. J. Bacteriol. 188: 7652-7660. DOI: [[https://doi.org/10.1128/JB.00795-06|10.1128/JB.00795-06]]

Lang JM, Pérez-Quintero AL, Koebnik R, DuCharme E, Sarra S, Doucoure H, Keita I, Ziegle J, Jacobs JM, Oliva R, Koita O, Szurek B, Verdier V, Leach JE (2019). A pathovar of //Xanthomonas oryzae //infecting wild grasses provides insight into the evolution of pathogenicity in rice agroecosystems. Front. Plant Sci. 10: 1–15. DOI: [[https://doi.org/10.1094/MPMI-07-16-0137-R|10.3389/fpls.2019.00507]]

Li G, Froehlich JE, Elowsky C, Msanne J, Ostosh AC, Zhang C, Awada T, Alfano JR, (2014). Distinct //Pseudomonas //type-III effectors use a cleavable transit peptide to target chloroplasts. Plant J. 77: 310–321. DOI: [[https://doi.org/10.1111/tpj.12396|10.1111/tpj.12396]]

Popov G, Fraiture M, Brunner F, Sessa G (2016). Multiple //Xanthomonas euvesicatoria//  type III effectors inhibit flg22-triggered immunity. Mol. Plant Microbe Interact. 29: 651-660. DOI: [[https://doi.org/10.1094/MPMI-07-16-0137-R|10.1094/MPMI-07-16-0137-R]]

Roden JA, Belt B, Ross JB, Tachibana T, Vargas J, Mudgett MB (2004). A genetic screen to isolate type III effectors translocated into pepper cells during //Xanthomonas//  infection. Proc. Natl. Acad. Sci. USA 101: 16624-16629. DOI: [[https://doi.org/10.1073/pnas.0407383101|10.1073/pnas.0407383101]]

Sohn KH, Zhang Y, Jones JD (2009). The //Pseudomonas syringae//  effector protein, AvrRPS4, requires in planta processing and the KRVY domain to function. Plant J. 57: 1079-1091. DOI: [[https://doi.org/10.1111/j.1365-313X.2008.03751.x|10.1111/j.1365-313X.2008.03751.x]] FIXME  Information needs to be added to the profile.

Teper D, Sunitha S, Martin GB, Sessa G (2015). Five //Xanthomonas//  type III effectors suppress cell death induced by components of immunity-associated MAP kinase cascades. Plant Signal. Behav. 10: e1064573. DOI: [[https://doi.org/10.1080/15592324.2015.1064573|10.1080/15592324.2015.1064573]]