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Molecular Diagnosis and Diversity for Regulated Xanthomonas
Bacterial virulence factors
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Author: Coline Sciallano
Internal reviewer: Gábor Rákheli
Expert reviewer: 
Class: XopV
Family: XopV
Prototype: XOO3803 (Xanthomonas oryzae pv. oryzae; strain MAFF 311018)
RefSeq ID: WP_027703842.1 (331 aa)
3D structure: Unknown
XopV was discovered via genome-wide screening for effector candidates in X. oryzae pv. oryzae (Xoo) strain MAFF 311018 in accordance with three criteria: i) ORF encoding proteins homologous to effectors of P. syringae strains and X. campestris pv. vesicatoria, ii) HrpX regulons preceded by two cis elements (Plant Induced Promoter, PIP ; and -10 box-like motif) or iii) proteins with an N-terminal amino acid composition similar to known effectors (more than 10% of Ser in the first 50 amino aa, no Asp or Glu residues in the first 12 aa, and an aliphatic amino acid or Pro at the third or fourth position) (Furutani et al., 2009).
XopV (XOO3803 in Furutani et al., 2009) has been shown to be translocated through the T3SS thanks to a XopV fusion with a calmodulin-dependant adenylate cyclase reporter in Xanthomonas oryzae, and further tests using a T3SS deficient strain (Furutani et al., 2009).
Expression of XopV has been shown to be regulated by HrpX using a construction with xopV and an adenylate cyclase reporter system in hrp-inducing medium. Also, no adenylate cyclase activity and no xopV transcript accumulation could be detected in a hrpX deficient strain with the same construction (Furutani et al., 2009).
qRT-PCR revealed that transcript levels of 15 out of 18 tested non-TAL effector genes (as well as the regulatory genes hrpG and hrpX), including xopV, were significantly reduced in the Xoo ΔxrvC mutant compared with those in the wild-type strain PXO99A (Liu et al., 2016).
An individual mutant for xopV in Xoo PXO99A did not show reduced virulence on rice variety Kitaake and IR24 (Song & Yang, 2010). A significant reduction in lesion length on Kitaake was observed when inoculated by leaf-clipping with a triple mutant of PXO99A for xopV, xopZ (two copies) and xopN. But interestingly, no differences in virulence were observed when comparing the WT PXO99A strain and individual or double mutants for each of these effectors (xopV, xopZ, xopN). Altogether, these information indicate XopV as one small of the collective contributors to Xoo virulence (Long et al., 2018).
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).
Unknown.
Unknown.
Unknown.
Yes, examples: X. campestris, X. euvesicatoria, X. oryzae, X. vasicola, X. phaseoli, X. citri, X. axonopodis.
Yes, examples: Pseudomonas cissicola, Ralstonia solanacearum, Acidovorax citrulli.
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. 104: 332-350. DOI: 10.1111/tpj.14924
Furutani A, Takaoka M, Sanada H, Noguchi Y, Oku T, Tsuno K, Tsuge S (2009). Identification of novel type III secretion effectors in Xanthomonas oryzae pv. oryzae. Mol. Plant Microbe Interact. 22: 96-106. DOI: 10.1094/mpmi-22-1-0096
Liu Y, Long J, Shen D, Song C (2016). Xanthomonas oryzae pv. oryzae requires H-NS-family protein XrvC to regulate virulence during rice infection. FEMS Microbiol. Lett. 363: fnw067. DOI: 10.1093/femsle/fnw067
Long J, Song C, Yan F, Zhou J, Zhou H, Yang B (2018). Non-TAL effectors from Xanthomonas oryzae pv. oryzae suppress peptidoglycan-triggered MAPK activation in rice. Front. Plant Sci. 12: 1857. DOI: 10.3389/fpls.2018.01857
Song C, Yang B (2010). Mutagenesis of 18 type III effectors reveals virulence function of XopZPXO99 in Xanthomonas oryzae pv. oryzae. Mol. Plant Microbe Interact. 23: 893-902. DOI: 10.1094/mpmi-23-7-0893
