====== The Type III Effector XopJ8 from //Xanthomonas// ======

Author: Anna Passelergue\\
Internal reviewer: [[https://www.researchgate.net/profile/Ralf_Koebnik|Ralf Koebnik]]\\

Class: XopJ\\
Family: XopJ8\\
Prototype: FZ025_RS03100 (//Xanthomonas// //hyacinthi//, strain CFBP 1156)\\
GenBank ID: [[https://www.ncbi.nlm.nih.gov/protein/QGY75705.1|QGY75705.1]] (362 aa)\\
RefSeq ID: [[https://www.ncbi.nlm.nih.gov/protein/WP_104559054.1|WP_104559054.1]] (362 aa).\\
3D structure: Unknown

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

=== How discovered? ===

XopJ8 was discovered as an ORF that is encoded downstream of a PIP box and a properly spaced ‐10 promoter motif (TTCGB‐N<sub>15</sub> ‐TTCGB‐N<sub>30–32</sub> ‐YANNNT) (Passelergue, 2025). Additional evidence came from the presence of conserved myristoylation and palmitoylation signals at the N terminus (Nimchuk //et al.//, 2000; Thieme //et al.//, 2007). The protein was also predicted as a type III effector by [[https://effectidor.tau.ac.il/|Effectidor II]], a pan-genomic AI-based algorithm for the prediction of type III secretion system effectors (Wagner //et al.//, 2025). The prototype gene in //X. hyacinthi// strain CFBP 1156 is flanked by two IS//3//-family insertion sequences.

=== (Experimental) evidence for being a T3E ===

XopJ8 was shown to have a functional type III secretion signal using a reporter fusion with AvrBs1 (Zhao //et al.//, 2013).

=== Regulation ===

The presence of a PIP box and a properly spaced ‐10 promoter motif (TTCGB‐N<sub>15</sub> ‐TTCGB‐N<sub>30–32</sub> ‐YANNNT) suggests that the //xopJ8// gene is under control of HrpG and HrpX (Wengelnik & Bonas, 1996; Wengelnik //et al.//, 1996; Koebnik //et al.//, 2006).

=== Phenotypes ===

Unknown.

=== Localization ===

The presence of conserved myristoylation and palmitoylation signals at the N terminus suggests that the protein is localized to the plasma membrane in the plant host cell (Nimchuk //et al.//, 2000; Thieme //et al.//, 2007).

=== Enzymatic function ===

Unknown.

=== Interaction partners ===

Unknown.

===== Conservation =====

=== In xanthomonads ===

Yes (//e.g.//, //X. citri//, frameshifted versions of the gene exist in //X. graminis// pv. //graminis//).

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

Yes (e.g., //Pseudomonas syringae//, //Ralstonia// ssp.].

===== References =====

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]]

Nimchuk Z, Marois E, Kjemtrup S, Leister RT, Katagiri F, Dangl JL (2000). Eukaryotic fatty acylation drives plasma membrane targeting and enhances function of several type III effector proteins from Pseudomonas syringae. Cell 101: 353-363. DOI: [[https://doi.org/10.1016/s0092-8674(00)80846-6|10.1016/s0092-8674(00)80846-6]]

Passelergue A (2025). Discovery of eight type III effector genes harboring the PIP box in clade-I xanthomonads. Master's thesis, Université de Montpellier, France.

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]]

Wagner N, Baumer E, Lyubman I, Shimony Y, Bracha N, Martins L, Potnis N, Chang JH, Teper D, Koebnik R, Pupko T (2025). Effectidor II: a pan-genomic AI-based algorithm for the prediction of type III secretion system effectors. Bioinformatics 41: btaf272. DOI: [[https://doi.org/10.1093/bioinformatics/btaf272|10.1093/bioinformatics/btaf272]]

Wengelnik K, Bonas U (1996). HrpXv, an AraC-type regulator, activates expression of five of the six loci in the hrp cluster of //Xanthomonas campestris// pv. //vesicatoria//. J. Bacteriol. 178: 3462-3469. DOI: [[https://doi.org/10.1128/jb.178.12.3462-3469.1996|10.1128/jb.178.12.3462-3469.1996]]

Wengelnik K, Van den Ackerveken G, Bonas U (1996). HrpG, a key hrp regulatory protein of //Xanthomonas campestris// pv. //vesicatoria// is homologous to two-component response regulators. Mol. Plant Microbe Interact. 9: 704-712. DOI: [[https://doi.org/10.1094/mpmi-9-0704|10.1094/mpmi-9-0704]]

Zhao S, Mo WL, Wu F, Tang W, Tang JL, Szurek B, Verdier V, Koebnik R, Feng JX (2013). Identification of non-TAL effectors in //Xanthomonas oryzae// pv. //oryzae// Chinese strain 13751 and analysis of their role in the bacterial virulence. World J. Microbiol. Biotechnol. 29: 733-744. DOI: [[https://doi.org/10.1007/s11274-012-1229-5|10.1007/s11274-012-1229-5]]

===== Acknowledgements =====

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