Author: Camila Ferdandes
Internal reviewer: Leonor Martins
Expert reviewer: Neha Potnis

Class: XopG
Family: XopG1, XopG2, XopG3
Prototype: XopG (Xanthomonas euvesicatoria pv. euvesicatoria, ex Xanthomonas campestris pv. vesicatoria; strain 85-10)
RefSeq ID: CAJ22929 (213 aa)
3D structure: Q3BW34 (homology model)

XopG was identified based on homology searches using TBLASTN analysis. Known T3E proteins from plant and animal pathogens were used as query against all contigs of the draft genomes of X. vesicatoria, X. gardneri and X. perforans with e-value of 10^-5 (Potnis et al., 2011).

The T3SS-dependent translocation evidence for XopG protein was confirmed using the AvrBs2 reporter gene assay (Thieme, 2006; Potnis et al., 2011).

XopG belongs to translocation class B and is still translocated in the absence of HpaB, being constitutively expressed (Schulze et al. 2012). XopG was identified as part of the putative HrpX regulon in X. campestris pv. campestris ATCC339138 (da Silva et al., 2002; White et al., 2009).

A deletion of xopG did not display differences in the induction of disease symptoms or hypersensibility response. XopG trigger cell death in different Solanaceae, including Nicotiana tabacum (White et al., 2009). XopG could be an essential pathogenicity factor in pepper (Potnis et al., 2011).

Agrobacterium-mediated transient expression of both XopQ and XopX in rice cells resulted in induction of rice immune responses, which were not observed when either protein was individually expressed. A screen for Xanthomonas effectors which can suppress XopQ-XopX induced rice immune responses, led to the identification of five effectors, namely XopU, XopV, XopP, XopG and AvrBs2, that could individually suppress these immune responses. These results suggest a complex interplay of Xanthomonas T3SS effectors in suppression of both pathogen-triggered immunity and effector-triggered immunity to promote virulence on rice (Deb et al., 2020).

Confocal laser scanning microscopy revealed a localization of XopG::GFP exclusively to the plant cell nucleus (Schulze et al. 2012).

XopG is a member of the HopH family from Pseudomonas syringae and encodes a protein with a putative zinc protease binding motif, typical of the zinc metalloproteases of the M27 family (similar to a clostridial toxin, botulinum toxin A from Clostridium botulinum) (Thieme, 2006; White et al., 2009; Schulze et al., 2012).

Unknown.

Yes (e.g., X. arboricola, X. campestris, X. citri, X. euvesicatoria, X. gardneri, X. oryzae, X. translucens, X. vesicatoria).

Yes (Ralstonia solanacearum, Pseudomonas spp., Acidovorax citrulli).

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Deb S, Ghosh P, Patel HK, Sonti RV (2020). Interaction of the Xanthomonas effectors XopQ and XopX results in induction of rice immune responses. Plant J., in press. DOI: 10.1111/tpj.14924

Potnis N, Krasileva K, Chow V, Almeida NF, Patil PB, Ryan RP, Sharlach M, Behlau F, Dow JM, Momol MT, 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: 10.1186/1471-2164-12-146

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Thieme F (2006). Genombasierte Identifizierung neuer potentieller Virulenzfaktoren von Xanthomonas campestris pv. vesicatoria. Doctoral Thesis, Martin-Luther-Universität Halle-Wittenberg, Germany. PDF: http://sundoc.bibliothek.uni-halle.de/diss-online/06/06H103/prom.pdf

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