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

Author: [[https://www.researchgate.net/profile/Jose_Gadea|Jose Gadea]]\\
Internal reviewer: [[https://www.researchgate.net/profile/Saul_Burdman|Saul Burdman]]

Class: XopAQ\\
Family: XopAQ\\
Prototype: XGA_2091 (//Xanthomonas hortorum// pv. //gardneri//, ex. //Xanthomonas gardneri//; strain 101 = ATCC 19865)\\
GenBank ID: [[https://www.ncbi.nlm.nih.gov/protein/EGD19295.1|EGD19295.1]] (95 aa)\\
RefSeq ID: [[https://www.ncbi.nlm.nih.gov/protein/WP_233366621.1|WP_233366621.1]] (93 aa)\\
3D structure: Unknown

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

=== How discovered? ===

XopAQ was predicted to be a type 3 effector based on homology to Rip6/11, a type 3 effector from //Ralstonia solanacearum// (Potnis //et al.//, 2011).
=== (Experimental) evidence for being a T3E ===

A functional screen to isolate //Ralstonia solanacearum// genes encoding proteins translocated into plant cells revealed that the genes //rip6 //and //rip11 //encode two new translocated proteins. XopAQ is 60% identical to Rip6 and Rip11. BlastP alignment between XopAQ and Rip6 indicates that the homology is spanned along the whole protein, including the N-terminal part, suggesting that the functional motif that drives translocation in Rip6 is conserved in XopAQ. Translocation assays using a strain deleted in the //hpaB //gene of //Ralstonia// indicates that Rip6 and Rip11 requires HpaB for their effective translocation into plant cells via the Hrp-T3SS (Mukaihara //et al//., 2010). However, to the best of our knowledge, no functional translocation assay has been performed for //Xanthomonas// XopAQ.
=== Regulation ===

The coding sequence of //xopAQ// from //X. gardneri// was found 68 bps downstream of a perfect PIP box (Potnis //et al.//, 2011). Similarly, in //X. arboricola// the //xopAQ //gene has a putative plant-inducible promoter box (PIP-BOX) sequence, 67 bp upstream of the TATA box (Garita-Cambronero, 2016). The //xopAQ//X. citri pv. //citri// 306 and //X. citri// pv. //citri// A<sup>w</sup>  12879 (restricted to Mexican lime) were grown in XVM2 (a medium that is known to induce expression of //hrp// genes and several effector genes in //Xanthomonas //sp.), as compared with nutrient broth (NB). However, no differential expression was observed for this gene among these two strains (Jalan //et al.//, 2013).
=== Phenotypes ===

Unknown.

=== Localization ===

CSS-Palm suite reveals potential myristoylation/palmitoylation motifs for XopAQ, suggesting that the protein could be targeted to the cytoplasmic membrane (Barak //et al//., 2016). This targeting is facilitated by a simple sequence motif at the N terminus of the polypeptide chain.
=== Enzymatic function ===

Unknown. No known motifs are found in the Rip6 and Rip11 proteins of //Ralstonia// (Mukaihara //et al//., 2010). No motifs are found in the //X. gardneri// protein neither (Prosite analysis).
=== Interaction partners ===

Unknown.

===== Conservation =====

=== In xanthomonads ===

Yes. The effector is widely present in the most agressive citrus canker-causing //X.citri// A strains but also in the AW strain (narrow host range) (Escalon //et al//., 2013; Garita-Cambronero //et al//., 2019), and also in the milder //X. fuscans// B strain, but not in the //X. fuscans// C strain, whic is restricted to //C. aurantifoli// (Dalio //et al//., 2017). Present in //Xanthomonas gardneri// but not in some strains of //X. perforans// nor //X. euvesicatoria// strains affecting pepper and tomato (Potnis //et al//., 2011; Schwartz //et al//., 2015; Vancheva //et al//., 2015; Jibrin //et al//., 2018). Two paralogs of XopAQ are present in strains 66b and LMG 918 of //X. euvesicatoria//, but not present in other LMG strains, 83b, 85-10, or //X. euvesicatoria// pv. //rosa// (Barak //et al//., 2016). Present in pathogenic but not in non-pathogenic// X. arboricola// pv. //pruni// (Garita-Cambronero //et al//., 2016, 2019). Absent in the related //X. juglandis// or //X. corylina// (Garita-Cambronero //et al//., 2018). Also present in //X. citri// pv. //viticola// (Schwartz //et al//., 2015) and other //X. citri// pathovars (blastp analysis). //X. phaseolis// //and X. populi//, among others, posess putative genes encoding proteins with moderate homology to XopAQ based on Blastp analysis.
=== In other plant pathogens/symbionts ===

Yes (//Ralstonia//).
===== 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]]

Dalio RJD, Magalhães DM, Rodrigues CM, Arena GD, Oliveira TS, Souza-Neto RR, Picchi SC, Martins PMM, Santos PJC, Maximo HJ, Pacheco IS, De Souza AA, Machado MA (2017). PAMPs, PRRs, effectors and R-genes associated with citrus-pathogen interactions. Ann. Bot. 119: 749-774. DOI: [[https://doi.org/10.1093/aob/mcw238|10.1093/aob/mcw238]]

Escalon A, Javegny S, Vernière C, Noël LD, Vital K, Poussier S, Hajri A, Boureau T, Pruvost O, Arlat M, Gagnevin L (2013). Variations in type III effector repertoires, pathological phenotypes and host range of //Xanthomonas citri// pv. //citri// pathotypes. Mol. Plant. Pathol. 14: 483-96. DOI: [[https://doi.org/10.1111/mpp.12019|10.1111/mpp.12019]]

Ferreira MASV, Bonneau S, Briand M, Cesbron S, Portier P, Darrasse A, Gama MAS, Barbosa MAG, Mariano RLR, Souza EB, Jacques MA (2009). //Xanthomonas citri// pv. //viticola// affecting grapevine in Brazil: Emergence of a successful monomorphic pathogen. Front. Plant Sci. 10: 489. DOI: [[https://doi.org/10.3389/fpls.2019.00489|10.3389/fpls.2019.00489]]

Garita-Cambronero J (2016). Genómica comparativa de cepas de //Xanthomonas arborícola// asociadas a //Prunus ssp//. Caracterización de los procesos de infección de la mancha bacteriana de frutales de hueso y almendro. Doctoral Thesis, Universidad Politécnica de Madrid, Spain. PDF: [[http://oa.upm.es/45480/|oa.upm.es/45480/]]

Garita-Cambronero J, Palacio-Bielsa A, Cubero J (2018). //Xanthomonas arboricola// pv. //pruni//, causal agent of bacterial spot of stone fruits and almond: its genomic and phenotypic characteristics in the //X. arboricola// species context. Mol. Plant Pathol. 19: 2053-2065. DOI: [[https://doi.org/10.1111/mpp.12679|10.1111/mpp.12679]]

Garita-Cambronero J, Palacio-Bielsa A, López MM, Cubero J (2016). Comparative genomic and phenotypic characterization of pathogenic and non-pathogenic strains of //Xanthomonas arboricola// reveals insights into the infection process of bacterial spot disease of stone fruits. PLoS One 11: e0161977. DOI: [[https://doi.org/10.1371/journal.pone.0161977|10.1371/journal.pone.0161977]]

Garita-Cambronero J, Sena-Vélez M, Ferragud E, Sabuquillo P, Redondo C, Cubero J (2019). //Xanthomonas citri// subsp. //citri// and //Xanthomonas arboricola// pv. //pruni//: Comparative analysis of two pathogens producing similar symptoms in different host plants. PLoS One 14: e0219797. DOI: [[https://doi.org/10.1371/journal.pone.0219797|10.1371/journal.pone.0219797]]

Jalan N, Kumar D, Andrade MO, Yu F, Jones JB, Graham JH, White FF, Setubal JC, Wang N (2013). Comparative genomic and transcriptome analyses of pathotypes of //Xanthomonas citri// subsp. //citri// provide insights into mechanisms of bacterial virulence and host range. BMC Genomics 14: 551. DOI: [[https://doi.org/10.1186/1471-2164-14-551|10.1186/1471-2164-14-551]]

Jibrin MO, Potnis N, Timilsina S, Minsavage GV, Vallad GE, Roberts PD, Jones JB, Goss EM (2018). Genomic inference of recombination-mediated evolution in //Xanthomonas euvesicatoria// and //X. perforans//. Appl. Environ. Microbiol. 84: e00136-18. DOI: [[https://doi.org/10.1128/AEM.00136-18|10.1128/AEM.00136-18]]

Mukaihara T, Tamura N, Iwabuchi M (2010). Genome-wide identification of a large repertoire of //Ralstonia solanacearum// type III effector proteins by a new functional screen. Mol. Plant Microbe Interact. 23: 251-262. [[https://doi.org/10.1094/MPMI-23-3-0251|10.1094/MPMI-23-3-0251]]

Potnis N, Krasileva K, Chow V, Almeida NF, Patil PB, Ryan RP, Sharlach M, Behlau F, Dow JM, Momol M, White FF, Preston JF, Vinatzer BA, Koebnik R, Setubal JC, Norman DJ, Staskawicz BJ, Jones JB (2011). Comparative genomics reveals diversity among xanthomonads infecting tomato and pepper. BMC Genomics 12: 146. DOI: [[https://doi.org/10.1186/1471-2164-12-146|10.1186/1471-2164-12-146]]

Schwartz AR, Potnis N, Timilsina S, Wilson M, Patané J, Martins J Jr, Minsavage GV, Dahlbeck D, Akhunova A, Almeida N, Vallad GE, Barak JD, White FF, Miller SA, Ritchie D, Goss E, Bart RS, Setubal JC, Jones JB, Staskawicz BJ (2015). Phylogenomics of //Xanthomonas// field strains infecting pepper and tomato reveals diversity in effector repertoires and identifies determinants of host specificity. Front. Microbiol. 6: 535. DOI: [[https://doi.org/10.3389/fmicb.2015.00535|10.3389/fmicb.2015.00535]]

Vancheva T, Lefeuvre P, Bogatzevska N, Moncheva P, Koebnik R (2015). Draf genome sequences of two //Xanthomonas euvesicatoria// strains from the Balkan Peninsula. Genome Announc. 3: e01528-14. DOI: [[https://mra.asm.org/content/3/1/e01528-14|10.1128/genomeA.01528-14]]

===== Acknowledgements =====

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