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

Author: [[https://www.researchgate.net/profile/Naama-Wagner|Naama Wagner]]\\
Internal reviewer: [[https://www.researchgate.net/profile/Ralf_Koebnik|Ralf Koebnik]]

Class: XopBH\\
Family: XopBH\\
Prototype: XTG_RS02340 (//Xanthomonas euroxanthea//, strain CPBF 424) Attention: The prototype sequence is too long because codons 18 to 39 overlap with the plant-inducible promoter (see below; Koebnik //et al.//, 2006).\\
GenBank ID: [[https://www.ncbi.nlm.nih.gov/protein/CAE1133144.1|CAJ22212.1]] (286 aa)\\
RefSeq ID: [[https://www.ncbi.nlm.nih.gov/protein/WP_212580660.1|WP_039417318.1]] (216 aa)\\
3D structure: Unknown

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

=== How discovered? ===

XopBH was discovered by a [[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 //xopBH// gene of strain CPBF 424 is located near the T3SS gene cluster, next to [[:bacteria:t3e:xopz|xopZ]] and [[:bacteria:t3e:xopf|xopF]], which are all encoded between //hrpE// and //hrpF// (Huguet & Bonas, 1997; Weber //et al.//, 2005).
=== (Experimental) evidence for being a T3E ===

XopBH 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 //xopBH// gene is under control of HrpG and HrpX (Wengelnik & Bonas, 1996; Wengelnik //et al.//, 1996; Koebnik //et al.//, 2006).
=== Phenotypes ===

Unknown.

=== Localization ===

Unknown.

=== Enzymatic function ===

Unknown.

=== Interaction partners ===

Unknown.

===== Conservation =====

=== In xanthomonads ===

Yes (//e.g.//, //X. arboricola//, //X. campestris// pv. //papavericola//, //X. hortorum//).
=== In other plant pathogens/symbionts ===

No.

===== References =====

Huguet E, Bonas U (1997). //hrpF// of //Xanthomonas campestris// pv. //vesicatoria// encodes an 87-kDa protein with homology to NoIX of //Rhizobium fredii//. Mo.l Plant Microbe Interact. 10: 488-498. DOI: [[https://doi.org/10.1094/MPMI.1997.10.4.488|10.1094/MPMI.1997.10.4.488]]

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]]

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, in press. DOI: [[https://doi.org/10.1093/bioinformatics/btaf272|10.1093/bioinformatics/btaf272]]

Weber E, Ojanen-Reuhs T, Huguet E, Hause G, Romantschuk M, Korhonen TK, Bonas U, Koebnik R (2005). The type III-dependent Hrp pilus is required for productive interaction of //Xanthomonas campestris// pv. //vesicatoria// with pepper host plants. J. Bacteriol. 187: 2458-2468. DOI: [[https://doi.org/10.1128/JB.187.7.2458-2468.2005|10.1128/JB.187.7.2458-2468.2005]]

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).