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Author: Isabel Rodrigues
Internal reviewer: Camila Fernandes
Expert reviewer: WANTED!

Class: XopH
Family: XopH1, XopH2
Prototype: AvrBs1.1 (Xanthomonas euvesicatoria pv. euvesicatoria, ex Xanthomonas campestris pv. vesicatoria; strain E3) (Ronald and Staskawicz, 1988)
GenBank ID (AvrBs1.1): P0A0W1.1 (104 aa)
GenBank ID (XopH1): CAP51755.1 (356 aa)
RefSeq ID: XopH1 WP_011345706.1 (356 aa), XopH2 WP_010377341.1 (380 aa)
Synonym: AvrBs1.1, AvrBs7 (Potnis et al., 2012)
3D structure: P0A0W1 (homology model)

Biological function

How discovered?

The XopH effector, also known as AvrBs1.1 (White et al., 2009), was first reported in 1988 (Ronald and Staskawicz 1988) and discovered due to its virulent activity (Gurenn et al., 2006). Later, this effector began to be identified based on the coregulation with the TTS system (Gurlebeck et al., 2006), most recently began to be identified by a combination of biochemical approaches, including a new NMR-based method to discriminate inositol polyphosphate enantiomers (Blüher et al., 2017).

(Experimental) evidence for being a T3E

The effector XopH, inhibited flg22-induced callose deposition in planta (Popov et al., 2016), dephosphorylates myo- inositol-hexakisphosphate (phytate, InsP6) to produce InsP5[1-OH], both in vitro and in vivo, and enhanced disease symptoms (Blüher et al., 2017; White and Jones 2018). The xopH activity can led to diminishing amounts of inositol pyrophosphates InsP7 and InsP8 (White and Jones 2018). It was also identified host changes in gene expression due to XopH activity (White and Jones 2018).




This effector can inhibit flg22- but not ABA-inducible reporter gene activation in protoplasts act as PTI inhibitors in planta and contribute to development of disease symptoms like chlorosis (Popov et al., 2016). XopH liberates phosphate from the plant tissue to improve the nutritional status of the pathogen what causes the plant show obvious symptoms of phosphorus deficiency (Blüher et al., 2017). Transgenic Nicotiana benthamiana plants constitutively expressing XopH were significantly smaller than transgenic GFP control plants of the same age and showed signs of early senescence indicating that the effector XopH might affect the ET pathway (Blüher et al., 2017). XopH sequester InsP6 by degrading it to an InsP5 isomer, which is not easily metabolized by the plant and accumulates what can compromise plant defense mechanism (Blüher et al., 2017).


The effector XopH is localized in the nucleus and in the cytoplasm of the plant cell (Popov et al., 2016; Blüher et al., 2017).

Enzymatic function

XopH is a T3E with phytate-degrading activity, in vitro and in planta (Blüher et al., 2017).

Interaction partners



In xanthomonads

Yes (e.g. Xanthomonas campestris pv. campestris (Potnis et al., 2012), Xanthomonas arboricola pv. corylina (Hajri et al., 2012), Xanthomonas euvesicatoria (White and Jones 2018)).

In other plant pathogens/symbionts



Blüher D, Laha D, Thieme S, Hofer A, Eschen-Lippold L, Masch A, Balcke G, Pavlovic I, Nagel O, Schonsky A, Hinkelmann R, Wörner J, Parvin N, Greiner R, Weber S, Tissier A, Schutkowski M, Lee J, Jessen H, Schaaf G, Bonas U (2017). A 1-phytase type III effector interferes with plant hormone signaling. Nat. Commun. 8: 2159. DOI: 10.1038/s41467-017-02195-8

Gurlebeck D, Thieme, F, Bonas U (2006). Type III effector proteins from the plant pathogen Xanthomonas and their role in the interaction with the host plant. J. Plant Physiol. 163: 233–255. DOI: 10.1016/j.jplph.2005.11.011

Hajri A, Pothier JF, Fischer-Le Saux M, Bonneau S, Poussier S, Boureau T, Duffy B, Manceau C (2011). Type three effector gene distribution and sequence analysis provide new insights into the pathogenicity of plant-pathogenic Xanthomonas arboricola. Appl Environ Microbiol. 78: 371-384. DOI: 10.1128/AEM.06119-11

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: 10.1094/mpmi-07-16-0137-r

Potnis N, Minsavage G, Smith J K, Hurlbert J C, Norman D, Rodrigues R, Stall R E, Jones JB (2012). Avirulence proteins AvrBs7 from Xanthomonas gardneri and AvrBs1.1 from Xanthomonas euvesicatoria contribute to a novel gene-for-gene interaction in Pepper. Mol. Plant Microbe Interact. 25: 307-320. DOI: 10.1094/MPMI-08-11-0205

Ronald PC, Staskawicz BJ (1988). The avirulence gene AvrBs1 from Xanthomonas campestris pv. vesicatoria encodes a 50-KD protein. Mol. Plant Microbe Interact. 1: 191-198.

White FF, Potnis N, Jones JB, Koebnik R (2009). The type III effectors of Xanthomonas. Mol. Plant Pathol. 10: 749-766. DOI: 10.1111/J.1364-3703.2009.00590.X

White FF, Jones JB (2018). One effector at a time. Nature Plants 4: 134-135. DOI: 10.1038/s41477-018-0114-0

Further reading

Thieme F (2006). Genombasierte Identifizierung neuer potentieller Virulenzfaktoren von Xanthomonas campestris pv. vesicatoria. Doctoral Thesis, Martin-Luther-Universität Halle-Wittenberg, Germany. PDF:

Thieme F, Koebnik R, Bekel T, Berger C, Boch J, Büttner D, Caldana C, Gaigalat L, Goesmann A, Kay S, Kirchner O, Lanz C, Linke B, McHardy AC, Meyer F, Mittenhuber G, Nies DH, Niesbach-Klösgen U, Patschkowski T, Rückert C, Rupp O, Schneiker S, Schuster SC, Vorhölter FJ, Weber E, Pühler A, Bonas U, Bartels D, Kaiser O (2005). Insights into genome plasticity and pathogenicity of the plant pathogenic bacterium Xanthomonas campestris pv. vesicatoria revealed by the complete genome sequence. J. Bacteriol. 187: 7254-7266. DOI: 10.1128/JB.187.21.7254-7266.2005

bacteria/t3e/xoph.txt · Last modified: 2023/10/02 21:25 by rkoebnik