====== XopAD ======

Author: [[https://www.researchgate.net/profile/David_Studholme|David J. Studholme]]\\
Internal reviewer: [[https://www.researchgate.net/profile/Laurent_Noel|Laurent D. Noël]]\\
Expert reviewer: FIXME

Class: XopAD\\
Family: XopAD\\
Prototype: XopAD (//Xanthomonas euvesicatoria// pv. //euvesicatoria//, ex //Xanthomonas campestris// pv. //vescicatoria//; strain 85-10)\\
RefSeq ID: not found in RefSeq. GenBank accession: [[https://www.ncbi.nlm.nih.gov/protein/CAJ26046.1|CAJ26046.1]] (614 aa)\\
3D structure: Unknown

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

=== How discovered? ===

XopAD was discovered using a machine-learning approach (Teper //et al//., 2016).
=== (Experimental) evidence for being a T3E ===

XopAD fused to the AvrBs2 reporter domain, was shown to translocate into plant cells in an //hrpF//-dependent manner.
=== Regulation ===

No PIP box was found in the promoter region of //xopAD// in //X. euvesicatoria// strain 85-10 (Teper //et al//., 2016).

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 //xopAD//, were significantly reduced in the //Xanthomonas oryzae// pv. //oryzae// Δ//xrvC// mutant compared with those in the wild-type strain PXO99<sup>A</sup>  (Liu //et al.//, 2016).
=== Phenotypes ===

Deletion of //xopAD// does not alter //X. citri// pv. //citri// (//Xci//) pathogenicity (Escalon //et al//., 2013).
=== Localization ===

Unknown.

=== Enzymatic function ===

Not known. However, ﻿the 614 amino acid protein consists of multiple [[https://www.ebi.ac.uk/interpro/beta/entry/InterPro/IPR011989/|armadillo repeats]] of semi-conserved 42 amino acids. The C-terminal domain, which is absent in //Xcv// 85-10 XopAD but present in the ~2880 amino acid homologues (see below), encodes a putative RelA-like nucleotidyltransferase domain (Teper //et al//., 2016).
=== Interaction partners ===

Not known.

===== Conservation =====

=== In xanthomonads ===

Yes. XopAD has homologues encoded in the genomes of most //Xanthomonas// species (Teper //et al//., 2016), including //X. axonopodis// (Harrison & Studholme, 2014), //X. vasicola// (Studholme //et al//., 2010; Wasukira //et al//., 2012), //X. nasturtii// (Vicente //et al//., 2010), //X. citri// (Escalon //et al//., 2013). In this respect, //Xanthomonas campestris// appears to be an exception. Escalon and colleagues state “The analysis of //xopAD// //and// //xopAG// suggested horizontal transfer between //X. citri //pv. //bilvae//, another citrus pathogen, and some //Xci// strains” (Escalon //et al//., 2013). The prototype sequence from //X. euvesicatoria// strain 85-10 (Teper //et al//., 2016) is 614 amino acids in length and marked in GenBank as a fragment. Homologues in other genomes of this species range from 2840 (RefSeq: [[https://www.ncbi.nlm.nih.gov/protein/WP_046939801.1|WP_046939801.1]]) to 2885 (RefSeq: [[https://www.ncbi.nlm.nih.gov/protein/WP_033837371.1|WP_033837371.1]]) amino acids in length and the authors of the prototype study state: “﻿//we hypothesize that the ORFs annotated as XCV1197 (XopAV) and XCV1198, and XCV4315 (XopAD), XCV4314 and XCV4313, were originally two complete ﻿ORFs that were later truncated by the introduction of early stop codons//” (Teper //et al//., 2016). Therefore, the full-length homologues found in other genomes might not be functionally equivalent to the prototype XopAD. The introduction of early stop codons is explained by presence of an ﻿IS//Xac5//-related insertion sequence (Escalon //et al//., 2013).
=== In other plant pathogens/symbionts ===

Yes. XopAD is homologous to members of the RipS1 family of effectors in //Ralstonia solanacearum// (Peeters //et al//., 2013).

===== References =====

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: 483-496. DOI: [[https://doi.org/10.1111/mpp.12019|10.1111/mpp.12019]]

Harrison J, Studholme DJ (2014). Draft genome sequence of //Xanthomonas axonopodis// pathovar //vasculorum// NCPPB 900. FEMS Microbiol. Lett. 360: 113-116. DOI: [[https://doi.org/10.1111/1574-6968.12607|10.1111/1574-6968.12607]]

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]]

Peeters N, Carrère S, Anisimova M, Plener L, Cazalé AC, Genin S (2013). Repertoire, unified nomenclature and evolution of the type III effector gene set in the //Ralstonia solanacearum// species complex. BMC Genomics 14: 859. DOI: [[https://doi.org/10.1186/1471-2164-14-859|10.1186/1471-2164-14-859]]

Studholme DJ, Kemen E, MacLean D, Schornack S, Aritua V, Thwaites R, Grant M, Smith J, Jones JD (2010). Genome-wide sequencing data reveals virulence factors implicated in banana //Xanthomonas// wilt. FEMS Microbiol. Lett. 310: 182-192. DOI: [[https://doi.org/10.1111/j.1574-6968.2010.02065.x|10.1111/j.1574-6968.2010.02065.x]]

Teper D, Burstein D, Salomon D, Gershovitz M, Pupko T, Sessa G (2016). Identification of novel //Xanthomonas euvesicatoria// type III effector proteins by a machine-learning approach. Mol. Plant Pathol. 17: 398-411. DOI: [[https://doi.org/10.1111/mpp.12288|10.1111/mpp.12288]]

Vicente JG, Rothwell S, Holub EB, Studholme DJ (2017). Pathogenic, phenotypic and molecular characterisation of //Xanthomonas nasturtii// sp. nov. and //Xanthomonas floridensis// sp. nov., new species of //Xanthomonas// associated with watercress production in Florida. Int. J. Syst. Evol. Microbiol. 67: 3645-3654. DOI: [[https://doi.org/10.1099/ijsem.0.002189|10.1099/ijsem.0.002189]]

Wasukira A, Tayebwa J, Thwaites R, Paszkiewicz K, Aritua V, Kubiriba J, Smith J, Grant M, Studholme DJ (2012). Genome-wide sequencing reveals two major sub-lineages in the genetically monomorphic pathogen //Xanthomonas campestris// pathovar //musacearum//. Genes (Basel) 3: 361-377. DOI: [[https://doi.org/10.3390/genes3030361|10.3390/genes3030361]]
