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--- bacteria:t3e:xopx [2026/10/29 15:07] – [References] rkoebnik
+++ bacteria:t3e:xopx [2026/10/29 15:12] (current) – [Biological function] rkoebnik
@@ Line 17: / Line 17: @@
 XopX was discovered through the screening of a genomic cosmid library of //X. euvesicatoria// strain GM98-38 conjugated in //X. campestris// pv. //campestris// that allowed //Xcc// to elicit an //Xcv// cell death-like response when inoculated on //N. benthamiana// (Metz //et al//., 2005).
 === (Experimental) evidence for being a T3E ===
 Translational fusions of XopX with the calmodulin-dependent adenylate cyclase domain of //Bordetella pertussis// (Cya) were exchanged by simple homologous recombination into the genomic copy of //xopX// of //X. euvesicatoria// strains 85* (constitutive //hrp// expression mutant), 85* Δ//hrcV// (T3SS-defective mutant) and wild-type GM98-38. All Cya fusion strains except 85* Δ//hrcV// still induced cell death response activity in //N. benthamiana//. Moreover, leaf extracts of //N. benthamiana// inoculated with these fusion strains were assayed for cAMP, and only strains with a functional T3SS showed an increase in cAMP levels due to translocation of the Cya reporter protein into the plant (Metz //et al//., 2005).
 === Regulation ===
-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 //xopX//, were significantly reduced in the //Xanthomonas oryzae// pv. //oryzae// Δ//xrvC// mutant compared with those in the wild-type strain PXO99<sup>A</sup> (Liu //et al.//, 2016).
+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 //xopX//, were significantly reduced in the //Xanthomonas oryzae// pv. //oryzae// Δ//xrvC// mutant compared with those in the wild-type strain PXO99<sup>A</sup>  (Liu //et al.//, 2016).
 === Phenotypes ===
   * XopX was demonstrated to be cytotoxic when expressed in yeast, suggesting it may target a conserved eukaryotic cell process required for cell viability (Salomon //et al//., 2011).
-  * During infection of rice (//Oryza sativa//) with //Xanthomonas oryzae// pv. //oryzae//, XopX was shown to be an inhibitor of rice innate immune response, as it suppresses LipA-induced callose deposition (Sinha //et al//., 2013).
+  * During infection of rice (//Oryza sativa//) with //Xanthomonas oryzae//  pv. //oryzae//, XopX was shown to be an inhibitor of rice innate immune response, as it suppresses LipA-induced callose deposition (Sinha //et al//., 2013).
-  * XopX is required for the development of //X. euvesicatoria//- induced symptoms in the bacterial spot disease of tomato (//Solanum lycopersicum//) and pepper (//Capsicum annuum//). Indeed, it promotes ethylene production, and therefore chlorosis and plant cell death during infection by //X. euvesicatoria// of susceptible tomato and in transient expression assays in tobacco. Interestingly, it also suppresses flagellin-induced production of reactive oxygen species (ROS) while promoting the accumulation of pattern-triggered immunity (PTI) gene transcripts (Stork //et al//., 2015). Eventually, the complex behavior of XopX //in planta//, which combines activation and suppression of immunity-related plant responses at the same time, allows to classify this effector with the T3Es that activates the plant ‘default to death and defense’ response (Lindeberg //et al//., 2012; Stork //et al//., 2015).
+  * XopX is required for the development of //X. euvesicatoria//- induced symptoms in the bacterial spot disease of tomato (//Solanum lycopersicum//) and pepper (//Capsicum annuum//). Indeed, it promotes ethylene production, and therefore chlorosis and plant cell death during infection by //X. euvesicatoria//  of susceptible tomato and in transient expression assays in tobacco. Interestingly, it also suppresses flagellin-induced production of reactive oxygen species (ROS) while promoting the accumulation of pattern-triggered immunity (PTI) gene transcripts (Stork //et al//., 2015). Eventually, the complex behavior of XopX //in planta//, which combines activation and suppression of immunity-related plant responses at the same time, allows to classify this effector with the T3Es that activates the plant ‘default to death and defense’ response (Lindeberg //et al//., 2012; Stork //et al//., 2015).
-  * XopX is required for full virulence in //Xanthomonas axonopodis// pv. //manihotis// CIO151 strain. A //Xam// strain deleted for //xopX//  showed decreased ability to produce symptoms in leaves of cassava. Also, the //xopX// KO reached more than one log unit lower populations than those observed for the wild‐type strain. This underlies the importance of this effector for disease developement (Medina //et al//., 2018).
+  * XopX is required for full virulence in //Xanthomonas axonopodis//  pv. //manihotis//  CIO151 strain. A //Xam//  strain deleted for //xopX//  showed decreased ability to produce symptoms in leaves of cassava. Also, the //xopX//  KO reached more than one log unit lower populations than those observed for the wild‐type strain. This underlies the importance of this effector for disease developement (Medina //et al//., 2018).
-  * When expressed in //Pseudomonas fluorescens// 55 (//Pf//55), a non‐pathogenic bacterium capable of eliciting PTI (callose deposit) in //Arabidopsis// Col‐0 plants, XopX is not able to reduce callose deposit, suggesting in these conditions, the effector is not able to suppress PTI. Using the same heterologous system, XopX is not able to suppress the HR triggered by Pf 55 HopA1 on tobacco, suggesting that is these conditions, XopX do not act as an ETI suppressor. (Medina //et al//., 2018).
+  * When expressed in //Pseudomonas fluorescens//  55 (//Pf//55), a non‐pathogenic bacterium capable of eliciting PTI (callose deposit) in //Arabidopsis//  Col‐0 plants, XopX is not able to reduce callose deposit, suggesting in these conditions, the effector is not able to suppress PTI. Using the same heterologous system, XopX is not able to suppress the HR triggered by Pf 55 HopA1 on tobacco, suggesting that is these conditions, XopX do not act as an ETI suppressor. (Medina //et al//., 2018).
-  * When transiently expressed in //N. benthamiana// by //Agrobacterium tumefaciens//–mediated expression system, XopX from //X. oryzae// pv. //oryzicola// cause the nonhost HR at approximately 2 days (Li //et al//., 2015).
+  * When transiently expressed in //N. benthamiana//  by //Agrobacterium tumefaciens//–mediated expression system, XopX from //X. oryzae//  pv. //oryzicola//  cause the nonhost HR at approximately 2 days (Li //et al//., 2015).
-  * A Δ//xopX// mutant strain of //Xanthomonas phaseoli// pv. //manihotis// (aka //Xanthomonas axonopodis// pv. //manihotis//) showed reduced growth //in planta// and delayed spread through the vascular system of cassava (Mutka //et al.//, 2016).
+  * A Δ//xopX//  mutant strain of //Xanthomonas phaseoli//  pv. //manihotis//  (aka //Xanthomonas axonopodis//  pv. //manihotis//) showed reduced growth //in planta//  and delayed spread through the vascular system of cassava (Mutka //et al.//, 2016).
-  * //Agrobacterium//-mediated transient expression of both //Xanthomonas oryzae// pv. //oryzae// 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).
+  * //Agrobacterium//-mediated transient expression of both //Xanthomonas oryzae//  pv. //oryzae//  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 oryzae// pv. //oryzae// 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).
+  * A screen for //Xanthomonas oryzae//  pv. //oryzae//  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).
-  * (ACD57163) is one among the five classes of virulence genes found to be upregulated in the //Xanthomonas oryzae// pv. //oryzae// MAI1 strain during infection. //xopX// was up-regulated at both 3 and 6 dai (Soto-Suárez //et al.//, 2010)
+  * (ACD57163) is one among the five classes of virulence genes found to be upregulated in the //Xanthomonas oryzae//  pv. //oryzae//  MAI1 strain during infection. //xopX//  was up-regulated at both 3 and 6 dai (Soto-Suárez //et al.//, 2010)
-  * The //xopX// gene contributes to the virulence of //Xanthomonas campestris// pv. //vesicatoria// on hosts pepper and tomato. XopX targets the innate immune response, resulting in enhanced plant disease susceptibility (Metz //et al//., 2005).
+  * The //xopX//  gene contributes to the virulence of //Xanthomonas campestris//  pv. //vesicatoria//  on hosts pepper and tomato. XopX targets the innate immune response, resulting in enhanced plant disease susceptibility (Metz //et al//., 2005).
-  * A //Xanthomonas campestris//pv. //vesicatoria xopX// mutant strain could not induce cell death response in //N. benthamiana//, and could be complemented back to cell death response on //N. benthamiana// in trans with plasmid subclones of //xopX// (Metz //et al//., 2005).
+  * A //Xanthomonas campestris//pv. //vesicatoria xopX//  mutant strain could not induce cell death response in //N. benthamiana//, and could be complemented back to cell death response on //N. benthamiana//  in trans with plasmid subclones of //xopX//  (Metz //et al//., 2005).
+  * Deletion of //xopX<sub>Xcc</sub> //  increased disease indices by more than 10% in cabbage line G1180, while bacterial counts also increased (Chen //et al.//, 2026).
+  * Transient expression of XopX//<sub>Xcc</sub> //  triggered a hypersensitive response in cabbage, and reverse transcription quantitative PCR (RT-qPCR) analyses revealed that XopX suppressed the expression of pathogenesis-related protein 1 (PR1) and of a WRKY transcription factor gene (WRKY33) associated with pattern-triggered immunity (Chen //et al.//, 2026).
 === Localization ===
-//Xanthomonas oryzae// pv. //oryzae// XopX wild-type protein localizes mostly to the nucleus, but is also present to a lesser extent in the peripheral cytoplasm. However, the XopX S193A and XopX S477A mutants of XopX, that are defective in binding to the rice 14-3-3 proteins GF14d and GF14e, were found to be unable to localize to the nucleus, and were mostly observed in the cytoplasm (Deb //et al.//, 2020).
+//Xanthomonas oryzae//  pv. //oryzae//  XopX wild-type protein localizes mostly to the nucleus, but is also present to a lesser extent in the peripheral cytoplasm. However, the XopX S193A and XopX S477A mutants of XopX, that are defective in binding to the rice 14-3-3 proteins GF14d and GF14e, were found to be unable to localize to the nucleus, and were mostly observed in the cytoplasm (Deb //et al.//, 2020).
 === Enzymatic function ===
@@ Line 52: / Line 51: @@
   * It has been suggested that XopX-triggering of plant cell death response was dependent on another cofactor delivered by the T3SS, yet still unknown (Metz //et al.//, 2005).
-  * The //Xanthomonas oryzae// pv. //oryzae// XopX interacts with two of the eight rice 14-3-3 proteins, GF14d and GF14e. Mutants of XopX that are defective in 14-3-3 binding are also defective in suppression of immune responses, suggesting that interaction with 14-3-3 proteins is required for suppression of host innate immunity (Deb //et al//., 2020).
+  * The //Xanthomonas oryzae//  pv. //oryzae//  XopX interacts with two of the eight rice 14-3-3 proteins, GF14d and GF14e. Mutants of XopX that are defective in 14-3-3 binding are also defective in suppression of immune responses, suggesting that interaction with 14-3-3 proteins is required for suppression of host innate immunity (Deb //et al//., 2020).
-  * Yeast two-hybrid, bimolecular fluorescence complementation (BiFC) and co-IP assays indicate that the //Xanthomonas oryzae// pv. //oryzae// XopX interacts with the type III effector XopQ (Deb //et al.//, 2020).
+  * Yeast two-hybrid, bimolecular fluorescence complementation (BiFC) and co-IP assays indicate that the //Xanthomonas oryzae//  pv. //oryzae//  XopX interacts with the type III effector XopQ (Deb //et al.//, 2020).
 ===== Conservation =====

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