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Molecular Diagnosis and Diversity for Regulated Xanthomonas
Bacterial virulence factors
This DokuWiki is based upon work from COST Action CA16107 EuroXanth, supported by COST (European Cooperation in Science and Technology)
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Author: Claude Bragard
Internal reviewer: Harrold van den Burg
Expert reviewer: 
Class: XopP
Family: XopP
Prototype: XopP (Xanthomonas euvesicatoria pv. euvesicatoria aka Xanthomonas campestris pv. vescicatoria; strain 85-10)
RefSeq ID: AY756270.1 (685 aa)
3D structure: Unknown
XopP was identified in a genetic screen, using a Tn5-based transposon construct harboring the coding sequence for the HR-inducing domain of AvrBs2, but devoid of the effectors' T3SS signal, that was randomly inserted into the genome of X. campestris pv. vesicatoria (Xcv) strain 85-10. The XopP::AvrBs2 fusion protein triggered a Bs2-dependent hypersensitive response (HR) in pepper leaves (Roden et al., 2004). XopP was also identified in X. campestris pv. campestris (Xcc) strain 8004 as a candidate T3E due to the presence of a plant-inducible promoter (PIP) box in its gene, XC_2994 (Jiang et al., 2009).
Type III-dependent secretion was confirmed using a calmodulin-dependent adenylate cyclase reporter assay, with a ΔhrpF mutant strain serving as negative control (Roden et al., 2004). Using an AvrBs1 reporter fusion, XopPXcc8004 was shown to be translated into plant cells in a hrpF- and hpaB-dependent manner (Jiang et al., 2009).
The xopP Xcc8004 gene contains a PIP box and was shown to be controlled by hrpG and hrpX (Jiang 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 xopP, were significantly reduced in the Xanthomonas oryzae pv. oryzae ΔxrvC mutant compared with those in the wild-type strain PXO99A (Liu et al., 2016).
Roden et al. did not find significant growth defects of a Xcv ΔxopP mutant in susceptible pepper and tomato leaves (Roden et al., 2004).
XopQXcc8004 is required for full virulence and growth of X. campestris pv. campestris in the host plant Chinese radish (Jiang et al., 2009).
XopPXoo is able to suppress rice pathogen associated molecular pattern (PAMP)-immunity and resistance to Xanthomonas oryzae pv. oryzae. Although XopPXoo is classified within the XopP, it shows only 40% sequence identity with the XopP homologue of X. campestris pv. campestris (Furutani et al., 2009). Therefore, it remains unclear if such interaction is similar in different pathosystems where XopP has been found.
XopPXoo co-localizes with OsPUB44 in the cytoplasm (Ishikawa et al., 2014).
Unknown.
XopPXoo interacts with the U-box domain of a rice ubiquitin E3 ligase, OsPUB44 and inhibits its activity (Ishikawa et al., 2014).
Yes (e.g., X. campestris, X. citri, X. euvesicatoria, X. oryzae, X. translucens). Since the G+C content of the xopP gene is similar to that of the Xcv hrp gene cluster, it may be a member of a “core” group of Xanthomonas spp. effectors (Roden et al., 2004).
Yes (e.g., Ralstonia solanacearum) (Roden et al., 2004).
Furutani A, Takaoka M, Sanada H, Noguchi Y, Oku T, Tsuno K, Ochiai H, 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
Ishikawa K, Yamaguchi K, Sakamoto K, Yoshimura S, Inoue K, Tsuge S, Kojima C, Kawasaki T (2014). Bacterial effector modulation of host E3 ligase activity suppresses PAMP-triggered immunity in rice. Nat. Commun. 5: 5430. DOI: 10.1038/ncomms6430
Jiang W, Jiang B, Xu R, Huang J, Wei H, Jiang GF, Cen WJ, Liu J, Ge YY, Li GH, Su LL, Hang XH, Tang DJ, Lu GT, Feng JX, He YQ, Tang JL (2009). Identification of six type III effector genes with the PIP box in Xanthomonas campestris pv. campestris and five of them contribute individually to full pathogenicity. Mol. Plant Microbe Interact. 22: 1401-1411. DOI: 10.1094/MPMI-22-11-1401
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
Roden JA, Belt B, Ross JB, Tachibana T, Vargas J, Mudgett MB (2004). A genetic screen to isolate type III effectors translocated into pepper cells during Xanthomonas infection. Proc. Natl. Acad. Sci. USA 101: 16624-16629. DOI: 10.1073/pnas.0407383101
