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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: Jakub Pečenka
Internal reviewer: Joana G. Vicente
Expert reviewer: 
Class: XopN
Family: XopN
Prototype: XopN (Xanthomonas euvesicatoria pv. euvesicatoria aka Xanthomonas campestris pv. vescicatoria; strain 85-10)
RefSeq ID: NP_643095 (733 aa)
3D structure: unknown - similar to phosphatase 2a (pr65 / A) (Roden et al., 2004).
XopN 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 Xcv strain 85-10. The XopN::AvrBs2 fusion protein triggered a Bs2-dependent hypersensitive response (HR) in pepper leaves (Roden et al., 2004).
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).
Start codon of xopN was found downstream if a conserved cis-regulatory element, the plant-inducible promoter (PIP) box (TTCGG-N15-TTCTG). xopN is regulated by hrpX and hrpG genes (Cheong et al., 2013; Jiang et al., 2008).
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) were significantly reduced in the Xanthomonas oryzae pv. oryzae ΔxrvC mutant compared with those in the wild-type strain PXO99A , but this did not apply to xopN (Liu et al., 2016).
XopN was localized by confocal microscopy using fluorescent tagged fusion (yellow fluorescent protein [YFP]-XopN). [YFP]-XopN was localized throughout the plant cytoplasm and also associated with the plant plasma membrane (PM) (Kim et al., 2009).
Unknown – Kim et al. (2009) did not confirm that XopN is an enzyme (Kim et al., 2009).
XopN interact with two types of proteins in tomato: Tomato Atypical Receptor-like Kinase1 (TARK1) and four Tomato Fourteen-Three-Three isoforms (TFT1, TFT3, TFT5, and TFT6) (Kim et al., 2009).
Yes (e.g., X. campestris, X. citri, X. oryzae). Since the G+C content of the xopN 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., Pseudomonas spp.) (Kim et al., 2009).
Cheong H, Kim CY, Jeon JS, Lee BM, Sun Moon J, Hwang I (2013). Xanthomonas oryzae pv. oryzae type III effector XopN targets OsVOZ2 and a putative thiamine synthase as a virulence factor in rice. PloS ONE 8(9): e73346. DOI: 10.1371/journal.pone.0073346.
Jiang B, He Y, Cen W, Wei H, Jiang G, Jiang W, Hang X, Feng J, Lu G, Tang D, Tang J (2008). The type III secretion effector XopXccN of Xanthomonas campestris pv. campestris is required for full virulence. Res. Microbiol. 159(3): 216-220. DOI: 10.1016/j.resmic.2007.12.004.
Kim JG, Li X, Roden JA, Taylor KW, Aakre CD, Su B, Landone S, Kirik A, Chen Y, Baranage G, Martin BG, Mudgett BM, McLane H (2009). Xanthomonas T3S effector XopN suppresses PAMP-triggered immunity and interacts with a tomato atypical receptor-like kinase and TFT1. The Plant Cell 21(4): 1305-1323. DOI: 10.1105/tpc.108.063123.
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. U.S.A. 101(47): 16624-16629. DOI: 10.1073/pnas.0407383101.
