Differences

This shows you the differences between two versions of the page.

--- bacteria:t3e:xopj2 [2024/11/04 12:02] – [Conservation] rkoebnik
+++ bacteria:t3e:xopj2 [2025/02/13 11:40] (current) – jfpothier
@@ Line 26: / Line 26: @@
 === Phenotypes ===
-  * AvrBsT was found to suppress the hypersensitive response (HR) that is elicited by the effector protein AvrBs1 from //Xee//  in resistant pepper plants. HR suppression occurs inside the plant cell and depends on a conserved predicted catalytic residue of AvrBsT (Szczesny //et al//., 2010).
+  * AvrBsT was found to suppress the hypersensitive response (HR) that is elicited by the effector protein AvrBs1 from //Xee// in resistant pepper plants. HR suppression occurs inside the plant cell and depends on a conserved predicted catalytic residue of AvrBsT (Szczesny //et al//., 2010).
   * AvrBsT was found to act as a virulence factor in tomato plants (Kim //et al//., 2010).
-  * Growth of //Xee//  strain Ds1 ectopically expressing //avrBsT//  was significantly enhanced in tomato leaves, whereas growth of //Xee//  strain Bv5-4a //ΔavrBsT//  was significantly reduced (Kim //et al//., 2010).
+  * Growth of //Xee// strain Ds1 ectopically expressing //avrBsT// was significantly enhanced in tomato leaves, whereas growth of //Xee// strain Bv5-4a //ΔavrBsT// was significantly reduced (Kim //et al//., 2010).
-  * AvrBsT also significantly compromised callose deposition and defense-marker gene expression in tomato plants when inoculating //Xee//  at high titer (Kim //et al//., 2010).
+  * AvrBsT also significantly compromised callose deposition and defense-marker gene expression in tomato plants when inoculating //Xee// at high titer (Kim //et al//., 2010).
-  * One out of 71 //Arabidopsis thaliana//  ecotypes, Pi-0, was found to recognize (HR) AvrBsT when delivered from //X. campestris//  pv. //campestris//  (Cunnac //et al//., 2007). //Pseudomonas syringae//  pv. //tomato//  (//Pst//) strain DC3000 expressing a hybrid protein consisting of a //Pst//  T3S signal derived from AvrRpt2 fused to AvrBsT-HA (haemagglutinin epitope tag) elicited HR and limited pathogen growth, confirming that the HR leads to defense (Cunnac //et al//., 2007). Pi-0 leaves infected with //Pst//  DC3000 expressing a hybrid protein containing a mutation in the catalytic core did not trigger, indicating that the Pi-0 HR is triggered by the putative enzymatic activity of AvrBsT (Cunnac //et al//., 2007).
+  * One out of 71 //Arabidopsis thaliana// ecotypes, Pi-0, was found to recognize (HR) AvrBsT when delivered from //X. campestris// pv. //campestris// (Cunnac //et al//., 2007). //Pseudomonas syringae// pv. //tomato// (//Pst//) strain DC3000 expressing a hybrid protein consisting of a //Pst// T3S signal derived from AvrRpt2 fused to AvrBsT-HA (haemagglutinin epitope tag) elicited HR and limited pathogen growth, confirming that the HR leads to defense (Cunnac //et al//., 2007). Pi-0 leaves infected with //Pst// DC3000 expressing a hybrid protein containing a mutation in the catalytic core did not trigger, indicating that the Pi-0 HR is triggered by the putative enzymatic activity of AvrBsT (Cunnac //et al//., 2007).
-  * Resistance in Pi-0 was found to be caused by a recessive mutation predicted to inactivate a carboxylesterase known to hydrolyze lysophospholipids and acylated proteins in eukaryotes. Transgenic Pi-0 plants expressing the wild-type allele from the //A. thaliana//  ecotype Columbia were susceptible to //Pst//  DC3000 AvrRpt2-AvrBsT-HA infection. These data indicated that the carboxylesterase inhibits AvrBsT-triggered phenotypes in //Arabidopsis//, and the resistance gene was therefore called //SOBER1//  (Suppressor Of AvrBsT-Elicited Resistance 1), where the inactive allele in Pi-0, //sober1-1//, provides resistance (Cunnac //et al//., 2007).
+  * Resistance in Pi-0 was found to be caused by a recessive mutation predicted to inactivate a carboxylesterase known to hydrolyze lysophospholipids and acylated proteins in eukaryotes. Transgenic Pi-0 plants expressing the wild-type allele from the //A. thaliana// ecotype Columbia were susceptible to //Pst// DC3000 AvrRpt2-AvrBsT-HA infection. These data indicated that the carboxylesterase inhibits AvrBsT-triggered phenotypes in //Arabidopsis//, and the resistance gene was therefore called //SOBER1// (Suppressor Of AvrBsT-Elicited Resistance 1), where the inactive allele in Pi-0, //sober1-1//, provides resistance (Cunnac //et al//., 2007).
-  * It was later shown that Pi-0 leaves infected with //Pst//  DC3000 expressing AvrBsT accumulated higher levels of phosphatidic acid (PA) compared to leaves infected with //Pst//  DC3000. Phospholipase D (PLD) activity was required for high PA levels and AvrBsT-dependent HR in Pi-0. Overexpression of SOBER1 in Pi-0 reduced PA levels and inhibited HR. These data implicated PA, phosphatidylcholine (PC) and lysophosphatidylcholine (LysoPC) as potential SOBER1 substrates. Recombinant His<sub>6</sub>-SOBER1 hydrolyzed PC but not PA or LysoPC in vitro indicating that the enzyme has phospholipase A2 (PLA2) activity. Chemical inhibition of PLA2 activity in leaves expressing SOBER1 resulted in HR in response to Pst DC3000 AvrBsT. These data were consistent with the model that SOBER1 PLA2 activity suppresses PLD-dependent production of PA in response to AvrBsT elicitation (Kirik //et al//., 2009).
+  * It was later shown that Pi-0 leaves infected with //Pst// DC3000 expressing AvrBsT accumulated higher levels of phosphatidic acid (PA) compared to leaves infected with //Pst// DC3000. Phospholipase D (PLD) activity was required for high PA levels and AvrBsT-dependent HR in Pi-0. Overexpression of SOBER1 in Pi-0 reduced PA levels and inhibited HR. These data implicated PA, phosphatidylcholine (PC) and lysophosphatidylcholine (LysoPC) as potential SOBER1 substrates. Recombinant His<sub>6</sub>-SOBER1 hydrolyzed PC but not PA or LysoPC in vitro indicating that the enzyme has phospholipase A2 (PLA2) activity. Chemical inhibition of PLA2 activity in leaves expressing SOBER1 resulted in HR in response to Pst DC3000 AvrBsT. These data were consistent with the model that SOBER1 PLA2 activity suppresses PLD-dependent production of PA in response to AvrBsT elicitation (Kirik //et al//., 2009).
-  * Transgenic //Arabidopsis//  plants overexpression AvrBsT upon dexamethasone (DEX) induction showed reduced susceptibility to infection with the obligate biotrophic oomycete //Hyaloperonospora arabidopsidis//  (Hwang //et al//., 2012). In contrast, plants overexpressing dexamethasone //(DEX)//://avrBsT//  exhibited enhanced susceptibility to //Pseudomonas syringae//  pv. //tomato//  (Pst) DC3000 infection (Hwang //et al//., 2012). Thus, AvrBsT overexpression leads to both disease and defense responses to microbial pathogens of different lifestyles (Hwang //et al//., 2012).
+  * Transgenic //Arabidopsis// plants overexpression AvrBsT upon dexamethasone (DEX) induction showed reduced susceptibility to infection with the obligate biotrophic oomycete //Hyaloperonospora arabidopsidis// (Hwang //et al//., 2012). In contrast, plants overexpressing dexamethasone //(DEX)//://avrBsT// exhibited enhanced susceptibility to //Pseudomonas syringae// pv. //tomato// (Pst) DC3000 infection (Hwang //et al//., 2012). Thus, AvrBsT overexpression leads to both disease and defense responses to microbial pathogens of different lifestyles (Hwang //et al//., 2012).
-  * Phylogenomics revealed that a host-range expansion of //X. euvesicatoria//  pv. //perforans//  (//Xep//) field strains on pepper is due, in part, to a loss of the effector AvrBsT. Further studies with //Xep//  demonstrated that a double deletion of //avrBsT//  and //xopQ//  allowed a host range expansion for //Nicotiana benthamiana//  (Schwartz //et al//., 2015).
+  * Phylogenomics revealed that a host-range expansion of //X. euvesicatoria// pv. //perforans// (//Xep//) field strains on pepper is due, in part, to a loss of the effector AvrBsT. Further studies with //Xep// demonstrated that a double deletion of //avrBsT// and //xopQ// allowed a host range expansion for //Nicotiana benthamiana// (Schwartz //et al//., 2015).
-  * Later, AvrBsT was found to contribute to fitness of //Xep//  on tomato plants under field conditions (Abrahamian //et al//., 2018).
+  * Later, AvrBsT was found to contribute to fitness of //Xep// on tomato plants under field conditions (Abrahamian //et al//., 2018).
-  * A variant of the canonical XopJ2 (XopJ2a) with only 70% sequence identity, **XopJ2b**, triggers a HR when translocated into pepper cells (Sharma et al., 2024). Like XopJ2a, XopJ2b triggers HR in Arabidopsis that is suppressed by the deacetylase, SOBER1 (Sharma et al., 2024).
+  * A variant of the canonical XopJ2 (XopJ2a) with only 70% sequence identity, XopJ2b, triggers a HR when translocated into pepper cells (Sharma //et al.//, 2024). Like XopJ2a, XopJ2b triggers HR in //Arabidopsis// that is suppressed by the deacetylase, SOBER1 (Sharma //et al.//, 2024).
 === Localization ===
-Transient coexpression of //CaHSP70a//  and //avrBsT//  under the control of the 35S promoter led to cytoplasmic localization of the CaHSP70a-AvrBsT complex and significantly enhanced //avrBsT//-triggered cell death in //Nicotiana benthamiana//  (Kim //et al//., 2015a).
+Transient coexpression of //CaHSP70a// and //avrBsT// under the control of the 35S promoter led to cytoplasmic localization of the CaHSP70a-AvrBsT complex and significantly enhanced //avrBsT//-triggered cell death in //Nicotiana benthamiana// (Kim //et al//., 2015a).
 === Enzymatic function ===
-AvrBsT belongs to the YopJ family, members of which were shown to act as cysteine proteases containing a catalytic triad (His, Glu, Cys). It was shown that AvrBsT requires a functional protease catalytic core to trigger defense responses in resistant plant cells, suggesting that AvrBsT acts as a protease to disrupt immune signaling pathways (Orth //et al//., 2000). AvrBsT was later shown to possess acetyltransferase activity and acetylates ACIP1 (for //ACETYLATED INTERACTING PROTEIN1//) from //Arabidopsis//. Genetic studies revealed that //Arabidopsis//  ACIP family members are required for both pathogen-associated molecular pattern (PAMP)-triggered immunity and AvrBsT-triggered ETI during //Pst//  DC3000 infection. Microscopy studies revealed that ACIP1 is associated with punctae on the cell cortex and some of these punctae co-localize with microtubules. Wild-type //Pst//  DC3000 or //Pst//  DC3000 AvrRpt2 infection triggered the formation of numerous, small ACIP1 punctae and rods. By contrast, //Pst//  DC3000 AvrBsT infection primarily triggered the formation of large GFP-ACIP1 aggregates, in an acetyltransferase-dependent manner. These data suggested that AvrBsT-dependent acetylation //in planta//  alters ACIP1’s defense function, which is linked to the activation of ETI (Cheong //et al//., 2014).
+AvrBsT belongs to the YopJ family, members of which were shown to act as cysteine proteases containing a catalytic triad (His, Glu, Cys). It was shown that AvrBsT requires a functional protease catalytic core to trigger defense responses in resistant plant cells, suggesting that AvrBsT acts as a protease to disrupt immune signaling pathways (Orth //et al//., 2000). AvrBsT was later shown to possess acetyltransferase activity and acetylates ACIP1 (for //ACETYLATED INTERACTING PROTEIN1//) from //Arabidopsis//. Genetic studies revealed that //Arabidopsis// ACIP family members are required for both pathogen-associated molecular pattern (PAMP)-triggered immunity and AvrBsT-triggered ETI during //Pst// DC3000 infection. Microscopy studies revealed that ACIP1 is associated with punctae on the cell cortex and some of these punctae co-localize with microtubules. Wild-type //Pst// DC3000 or //Pst// DC3000 AvrRpt2 infection triggered the formation of numerous, small ACIP1 punctae and rods. By contrast, //Pst// DC3000 AvrBsT infection primarily triggered the formation of large GFP-ACIP1 aggregates, in an acetyltransferase-dependent manner. These data suggested that AvrBsT-dependent acetylation //in planta// alters ACIP1’s defense function, which is linked to the activation of ETI (Cheong //et al//., 2014).
 === Interaction partners ===
@@ Line 50: / Line 50: @@
   * Yeast two-hybrid based analyses identified a putative regulator of sugar metabolism, SNF1-related kinase 1 (SnRK1), as an interactor of AvrBsT (Szczesny //et al//., 2010). Gene silencing experiments revealed that SnRK1 is required for the induction of the AvrBs1-specific HR, which is suppressed by AvrBsT (Szczesny //et al//., 2010). Thus, SnRK1 may be involved in the AvrBsT-mediated suppression of the AvrBs1-specific HR (Szczesny //et al//., 2010).
   * Later, the pepper SGT1 (for suppressor of the G2 allele of //skp1//) and PIK1 (for receptor-like cytoplasmic kinase1) were identified as host interactors of AvrBsT. SGT1 forms a heterotrimeric complex with both AvrBsT and PIK1 exclusively in the cytoplasm. PIK1 specifically phosphorylates SGT1 and AvrBsT in vitro. AvrBsT binding to SGT1 resulted in the inhibition of PIK1-mediated SGT1 phosphorylation and subsequent nuclear transport of the SGT1-PIK1 complex (Kim //et al//., 2014).
-  * Using a yeast two-hybrid screen, the pepper CaHSP70a was identified as another AvrBsT-interacting protein. Bimolecular fluorescence complementation and co-immunoprecipitation assays confirmed the specific interaction between CaHSP70a and AvrBsT //in planta//  (Kim //et al//., 2015a).
+  * Using a yeast two-hybrid screen, the pepper CaHSP70a was identified as another AvrBsT-interacting protein. Bimolecular fluorescence complementation and co-immunoprecipitation assays confirmed the specific interaction between CaHSP70a and AvrBsT //in planta// (Kim //et al//., 2015a).
-  * Using a yeast two-hybrid screen, the pepper aldehyde dehydrogenase 1 (CaALDH1) was identified as another AvrBsT-interacting protein. Bimolecular fluorescence complementation and co-immunoprecipitation assays confirmed the interaction between CaALDH1 and AvrBsT //in planta//  (Kim //et al//., 2015b).
+  * Using a yeast two-hybrid screen, the pepper aldehyde dehydrogenase 1 (CaALDH1) was identified as another AvrBsT-interacting protein. Bimolecular fluorescence complementation and co-immunoprecipitation assays confirmed the interaction between CaALDH1 and AvrBsT //in planta// (Kim //et al//., 2015b).
 ===== Conservation =====
@@ Line 61: / Line 61: @@
 Yes (//Acidovorax// spp., //Brenneria// spp., //Erwinia// spp., //Pseudomonas// spp., //Ralstonia// spp.).
-=====   =====
 ===== References =====
@@ Line 101: / Line 100: @@
 Schwartz AR, Potnis N, Timilsina S, Wilson M, Patané J, Martins J Jr, Minsavage GV, Dahlbeck D, Akhunova A, Almeida N, Vallad GE, Barak JD, White FF, Miller SA, Ritchie D, Goss E, Bart RS, Setubal JC, Jones JB, Staskawicz BJ (2015). Phylogenomics of //Xanthomonas// field strains infecting pepper and tomato reveals diversity in effector repertoires and identifies determinants of host specificity. Front. Microbiol. 6: 535. DOI: [[https://doi.org/10.3389/fmicb.2015.00535|10.3389/fmicb.2015.00535]]
-Sharma A, Iruegas-Bocardo F, Bibi S, Chen YC, Kim JG, Abrahamian P, Minsavage GV, Hurlbert JC, Vallad GE, Mudgett MB, Jones JB, Goss EM (2024). Multiple acquisitions of XopJ2 effectors in populations of //Xanthomonas perforans//. Mol. Plant Microbe Interact., in press. DOI: [[https://doi.org/10.1094/MPMI-05-24-0048-R|10.1094/MPMI-05-24-0048-R]]
+Sharma A, Iruegas-Bocardo F, Bibi S, Chen YC, Kim JG, Abrahamian P, Minsavage GV, Hurlbert JC, Vallad GE, Mudgett MB, Jones JB, Goss EM (2024). Multiple acquisitions of XopJ2 effectors in populations of //Xanthomonas perforans//. Mol. Plant Microbe Interact. 37: 736-747. DOI: [[https://doi.org/10.1094/MPMI-05-24-0048-R|10.1094/MPMI-05-24-0048-R]]
 Szczesny R, Büttner D, Escolar L, Schulze S, Seiferth A, Bonas U (2010). Suppression of the AvrBs1-specific hypersensitive response by the YopJ effector homolog AvrBsT from //Xanthomonas// depends on a SNF1-related kinase. New Phytol. 187: 1058-1074. DOI: [[https://doi.org/10.1111/j.1469-8137.2010.03346.x|10.1111/j.1469-8137.2010.03346.x]]
@@ Line 107: / Line 106: @@
 ===== Further reading =====
-Han SW, Hwang BK (2017). Molecular functions of //Xanthomonas//  type III effector AvrBsT and its plant interactors in cell death and defense signaling. Planta 245: 237-253. DOI: [[https://doi.org/10.1007/s00425-016-2628-x|10.1007/s00425-016-2628-x]]
+Han SW, Hwang BK (2017). Molecular functions of //Xanthomonas// type III effector AvrBsT and its plant interactors in cell death and defense signaling. Planta 245: 237-253. DOI: [[https://doi.org/10.1007/s00425-016-2628-x|10.1007/s00425-016-2628-x]]
 Timilsina S, Abrahamian P, Potnis N, Minsavage GV, White FF, Staskawicz BJ, Jones JB, Vallad GE, Goss EM (2016). Analysis of sequenced genomes of Xanthomonas perforans identifies candidate targets for resistance breeding in tomato. Phytopathology 106: 1097-1104. DOI: [[https://doi.org/10.1094/PHYTO-03-16-0119-FI|10.1094/PHYTO-03-16-0119-FI]]

EuroXanth DokuWiki

User Tools

Site Tools

Differences

Page Tools