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--- bacteria:t3e:xopq [2020/07/06 13:00]
rkoebnik [References]
+++ bacteria:t3e:xopq [2021/01/05 17:25] (current)
rkoebnik [References]
@@ Line 7: / Line 7: @@
 Class: XopQ\\
 Family: XopQ\\
-Prototype: XCV4438: Xanthomonas outer protein Q from //Xanthomonas euvesicatoria// pv. //euvesicatoria// strain 85-10 (aka //X. campestris// pv. //vesicatoria//, //Xcv//)\\
+Prototype: XCV4438 (//Xanthomonas euvesicatoria// pv. //euvesicatoria//, ex //Xanthomonas campestris// pv. //vesicatoria//; strain 85-10)\\
 RefSeq ID: [[https://www.ncbi.nlm.nih.gov/protein/WP_011349176.1|WP_011349176.1]] (464 aa)\\
 D structure: [[https://www.rcsb.org/structure/4kl0|4KL0]] (Yu //et al.//, 2013); [[https://www.rcsb.org/structure/4P5F|4P5F]] (Yu //et al.//, 2014)
 ===== Biological function =====
 === How discovered? ===
-XopQ was identified in a genetic screen, using a Tn//5//-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 XopQ::AvrBs2 fusion protein triggered a //Bs2//-dependent hypersensitive response (HR) in pepper leaves (Roden //et al//., 2004). XopQ 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_3177 (Jiang //et al.//, 2009).
+XopQ was identified in a genetic screen, using a Tn//5//-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 XopQ::AvrBs2 fusion protein triggered a //Bs2//-dependent hypersensitive response (HR) in pepper leaves (Roden //et al//., 2004). XopQ 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_3177 (Jiang //et al.//, 2009).
 === (Experimental) evidence for being a T3E ===
@@ Line 32: / Line 33: @@
   * Mutations of two potential active site residues, D116 and Y279, resulted in //Xoo//  mutants with reduced virulence on rice and reduced hypersensitive response (HR) on //Nicotiana benthamiana//, a nonhost. However, Arabidopsis lines expressing either xopQ or //xopQ// <sub>Y279A</sub>  were equally proficient at suppression of LipA-induced callose deposition (Gupta //et al.//, 2015).
   * Compatibility studies with //X. euvesicatoria//  pv. //perforans//  revealed that a double deletion of //avrBsT//  and //xopQ//  allows a host range expansion for //Nicotiana benthamiana//  (Schwartz //et al.//, 2015).
-  * XopQ mediated cell death suppression in //N. benthamiana//  during transient expression assays was later shown to result from an attenuation of //Agrobacterium//  ‐mediated protein expression rather than the reflecting a genuine XopQ virulence activity (Adlung & Bonas, 2017).
+  * The avirulence activity of XopQ derivatives did not correlate with macroscopically visible plant reactions upon transient expression in //N. benthamiana//. It was therefore speculated that //N. benthamiana//  might encode two resistance proteins for the recognition of XopQ (Adlung, 2016).
+  * Transient co-expression of XopQ::GFP and XopS::GFP in //N. benthamiana//  triggered cell death reactions, which were not observed when each effector was expressed alone. Bimolecular fluorescence complementation using split-YFP derivatives revealed that XopQ and XopS co-localize in the nucleus. These results suggested that both effectors may form a protein-protein complex i//n planta //  (Adlung, 2016).
+  * XopQ suppressed cell death reactions in //N. benthamiana//  that were triggered by three //Xcv//  type III effectors (XopB, XopJ, XopL), whereas cell death reactions triggered by AvrBsT were not suppressed by XopQ (Adlung, 2016).
+  * XopQ-mediated cell death suppression in //N. benthamiana//  during transient expression assays was later shown to result from an attenuation of //Agrobacterium//  ‐mediated protein expression rather than reflecting a genuine XopQ virulence activity (Adlung & Bonas, 2017).
   * A Δ//xopN//–Δ//xopQ //double knock-out mutant in //X. phaseoli//  pv. //manihotis//  (//Xpm//) was less aggressive in the cassava host plant than its single mutation counterparts. In addition, //in planta //  bacterial growth was reduced at 5 dpi in the double mutant with respect to the wild-type strain CIO151 and individual knock-out strains. The phenotype of the double mutant could be complemented when transforming a plasmid containing //xopQ//. These results confirmed that //xopN //and// xopQ //are functionally redundant in //Xpm//  (Medina //et al.//, 2017).
   * A reverse genetics screen identified Recognition of XopQ 1 (Roq1), a nucleotide-binding leucine-rich repeat (NLR) protein with a Toll-like interleukin-1 receptor (TIR) domain, which mediates XopQ recognition in //N. benthamiana//. Roq1 orthologs appear to be present only in the //Nicotiana//  genus. Expression of Roq1 was found to be sufficient for XopQ recognition in both the closely-related //Nicotiana sylvestris//  and the distantly-related beet plant (//Beta vulgaris//) (Schultink //et al.//, 2017).
@@ Line 41: / Line 45: @@
   * Roq1 was found to confer immunity to //Xanthomonas//  (containing XopQ), //P. syringae//  (containing the XopQ homolog HopQ1), and //Ralstonia//  (containing the XopQ homolog RipB) when expressed in tomato (Thomas //et al.//, 2020).
   * Strong resistance to //Xanthomonas euvesicatoria//  pv. //perforans//  was observed with transgenic tomato plants expressing Roq1 from //N. benthamiana//  in three seasons of field trials with both natural and artificial inoculation. The Roq1 gene can therefore be used to provide safe, economical, and effective control of these pathogens in tomato and other crop species and reduce or eliminate the need for traditional chemical controls (Thomas //et al.//, 2020).
+  * Agrobacterium-mediated transient expression of both XopQ and XopX in rice cells resulted in induction of rice immune responses. These immune responses were not observed when either protein was individually expressed in rice cells. XopQ-XopX induced rice immune responses were not observed with a XopX mutant that is defective in 14-3-3 binding (Deb //et al.//, 2020).
+  * 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).
 === Localization ===
@@ Line 57: / Line 63: @@
 Using protein-protein interaction studies in yeast and in planta, XopQ<sub>Xcv</sub>  was shown to physically interacts with the 14–3–3 protein TFT4 from tomato (//Solanum lycopersicum//) (Teper //et al.//, 2014). A mutation in the putative 14–3–3 binding site of XopQ (S65A) impaired interaction of the effector with TFT4 from pepper and tomato (//Capsicum annuum//) and its virulence function //in planta//  (Teper //et al.//, 2014). Yeast 2-hybrid assays revealed that XopQ<sub>Xcv</sub>  interacts with multiple, but perhaps not all 14–3–3 protein isoforms (Teper //et al.//, 2014; Dubrov //et al.//, 2018).
+Bimolecular fluorescence complementation assays upon transient expression in //N. benthamiana//  using split-YFP derivatives revealed that XopQ may interact with itself and also with XopS, maybe forming a large protein complex i//n planta //  (Adlung, 2016).
 Roq1, a nucleotide-binding leucine-rich repeat (NLR) protein with a Toll-like interleukin-1 receptor (TIR) domain, was found to co-immunoprecipitate with XopQ, suggesting a physical association between the two proteins (Schultink //et al.//, 2017).
-XopQ<sub>Xoo</sub>  was shown to interact in yeast and in planta with two rice 14–3–3 proteins, Gf14f and Gf14g (Deb //et al//., 2019). A serine to alanine mutation (S65A) of a 14–3–3 interaction motif in XopQ abolished the ability of XopQ to interact with the two 14–3–3 proteins and to suppress innate immunity.
+XopQ<sub>Xoo</sub>  was shown to interact in yeast and i//n planta//  with two rice 14–3–3 proteins, Gf14f and Gf14g (Deb //et al//., 2019). A serine to alanine mutation (S65A) of a 14–3–3 interaction motif in XopQ abolished the ability of XopQ to interact with the two 14–3–3 proteins and to suppress innate immunity.
+Yeast two-hybrid, bimolecular fluorescence complementation (BiFC) and co-IP assays indicated that XopQ and XopX interact with each other (Deb et al., 2020).
 ===== Conservation =====
@@ Line 81: / Line 91: @@
 Büttner D, Bonas U (2010). Regulation and secretion of //Xanthomonas// virulence factors. FEMS Microbiol. Rev. 34: 107-133. DOI: [[https://doi.org/10.1111/j.1574-6976.2009.00192.x|10.1111/j.1574-6976.2009.00192.x]]
+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: [[https://doi.org/10.1111/tpj.14924|10.1111/tpj.14924]]
 Deb S, Gupta MK, Patel HK, Sonti RV (2019). //Xanthomonas oryzae// pv. //oryzae// XopQ protein suppresses rice immune responses through interaction with two 14-3-3 proteins but its phospho-null mutant induces rice immune responses and interacts with another 14-3-3 protein. Mol. Plant Pathol. 20: 976-989. DOI: [[https://doi.org/10.1111/mpp.12807|10.1111/mpp.12807]]

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