Author: Jaime Cubero
Internal reviewer: Eran Bosis
Expert reviewer:

Class: XopE3
Family: XopE
Prototype: XAC3224 (Xanthomonas citri subsp. citri)
RefSeq ID: WP_011052114.1 (356 aa)
3D structure: Contains a catalytic triad of cysteine, histidine and aspartic acid, and have been grouped with peptide N-glycanases (PNGases, members of the transglutaminase protein superfamily). XopE3 contains N-myristoylation motifs (Dunger et al., 2012).

XopE3 (avrXacE2) was first identified by sequence homology searches (da Silva et al., 2002).

Homology to other XopE effectors.

avrXacE2 was shown to be regulated by HrpG regulon in X. citri (Guo et al., 2011). This effector does not contain PIP box-like sequences.

Lesions caused by mutants of X. citri on avrXacE2 show more extensive necrotic areas relative to those caused by wild-type bacteria in citrus leaves and grow slowly compared to wild type strain. This protein may function to attenuate cell death. No effect has been revealed on hypersensitive response (HR) on non-host plants (Dunger et al., 2012).

Conservation of XopE3 (avrXacE2) in three Xanthomonas strains causing Citrus Canker suggest that it may play a special role in citrus canker (Moreira et al., 2010).

Confocal microscopy imaging of N. benthamiana cells expressing avrXacE2-GFP fusion shows a localization mainly in the plant cell membrane and in the nucleus (Dunger et al., 2012).

XopE3 belongs to the HopX effector family, which are part of the transglutaminase superfamily (Nimchuk et al., 2007).

Not known.

Yes (e.g., X. citri, X. arboricola. X axonopodis).

Yes (Ralstonia, Pseudomonas, Acidovorax).

da Silva AC, Ferro JA, Reinach FC, Farah CS, Furlan LR, Quaggio RB, Monteiro-Vitorello CB, Van Sluys MA, Almeida NF, Alves LM, do Amaral AM, Bertolini MC, Camargo LE, Camarotte G, Cannavan F, Cardozo J, Chambergo F, Ciapina LP, Cicarelli RM, Coutinho LL, Cursino-Santos JR, El Dorry H, Faria JB, Ferreira AJ, Ferreira RC, Ferro MI, Formighieri EF, Franco MC, Greggio CC, Gruber A, Katsuyama AM, Kishi LT, Leite RP, Lemos EG, Lemos MV, Locali EC, Machado MA, Madeira AM, Martinez-Rossi NM, Martins EC, Meidanis J, Menck CF, Miyaki CY, Moon DH, Moreira LM, Novo MT, Okura VK, Oliveira, MC, Oliveira VR, Pereira HA, Rossi A, Sena JA, Silva C, de Souza RF, Spinola LA,Takita MA, Tamura RE, Teixeira EC, Tezza RI, Trindade dos SM, Truffi D, Tsai, SM, White FF, Setubal JC, Kitajima JP (2002). Comparison of the genomes of two Xanthomonas pathogens with differing host specificities. Nature 417(6887):459–463. DOI: 10.1038/417459a.

Dunger G, Garofalo CG, Gottig N, Garavaglia BS, Rosa MC, Farah CS, Orellano EG, Ottado J (2012). Analysis of three Xanthomonas axonopodis pv. citri effector proteins in pathogenicity and their interactions with host plant proteins. Mol Plant Pathol. 13(8):865-76. DOI: 10.1111/j.1364-3703.2012.00797.x.

Guo Y, Figueiredo F, Jones J, Wang N (2011). HrpG and HrpX play global roles in coordinating different virulence traits of Xanthomonas axonopodis pv. citri. Mol Plant Microbe Interact. 24(6):649-61. DOI: 10.1094/MPMI-09-10-0209.

Moreira LM, Almeida NF, Potnis N, Digiampietri LA, Adi SS, Bortolossi JC, da Silva AC, da Silva AM, de Moraes FE, de Oliveira JC, de Souza RF. Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp. aurantifolii. BMC genomics. 2010 Dec 1;11(1):238. DOI: 10.1186/1471-2164-11-238.

Nimchuk ZL, Fisher EJ, Desvaux D, Chang JH, Dangl JL (2007). The HopX (AvrPphE) family of Pseudomonas syringae type III effectors require a catalytic triad and a novel N-terminal domain forfunction. Mol. Plant-Microbe Interact. 20(4):346-357. DOI: 10.1094/MPMI-20-4-0346.