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--- bacteria:t3e:xopaa [2023/12/07 11:25] – [Biological function] rkoebnik
+++ bacteria:t3e:xopaa [2025/07/13 23:57] (current) – jfpothier
@@ Line 1: / Line 1: @@
-====== XopAA ======
+====== The Type III Effector XopAA from //Xanthomonas// ======
-Author: John Doe\\
+Author: [[https://www.researchgate.net/profile/Ralf-Koebnik|Ralf Koebnik]]\\
-Internal reviewer: Jane Doe \\
-Expert reviewer: **WANTED!**
 Class: XopAA\\
@@ Line 23: / Line 21: @@
 Transient expression of //xopAA// //in planta// using an //Agrobacterium tumefaciens//-mediated expression system induced a chlorotic phenotype independent of //Xanthomonas//, This demonstration that //xopAA// induces chlorosis when directly expressed by the host cell suggested that the loss of chlorosis induction in the //hrp// mutants was a direct effect of preventing T3SS-dependent translocation (Morales //et al.//, 2005).
-=== Regulation ===
-=== Phenotypes ===
+//Xanthomonas// bacteria carrying a translational fusion of XopAA to the calmodulin-dependent adenylate cyclase Cya produced approximately 30 times more cAMP in tomato leaves at 8 hpi when compared to bacteria with a mutation in the T3SS gene //hrcV// or bacteria that harbour a //recA//://cya// fusion. These results indicated that the //xopAA// gene product is translocated to host cells in a T3SS-dependent manner (Morales //et al.//, 2005).
-=== Localization ===
+=== Regulation ===
-=== Enzymatic function ===
+RT-PCR expression analyses suggested that, although translocation of XopAA is dependent on the Hrp T3SS apparatus, //xopAA// expression does not depend on nutritional conditions that induce //hrp// gene expression in //Xee// (Morales //et al.//, 2005).
-=== Interaction partners ===
+=== Phenotypes ===
-===== Conservation =====
+Transgenic rice plants expressing XopAA//<sub>Xoo</sub>// exhibited semi-dwarfism and a reduction in Brassinolide-dependent laminar inclination, characteristics of brassinosteroid (BR)-insensitive mutants caused by mutations of the BR receptor (Yamaguchi //et al.//, 2013).
-=== In xanthomonads ===
+Rice plants inoculated with a T3SS-deficient //hrpX// mutant of //X. oryzae// pv. //oryzae// (//Xoo//) did not develop disease lesions. In contrast, a transgenic rice line overexpressing //xopAA// showed severe lesions when inoculated with the //Xoo// //hrpX// mutant and the bacterial population of the //hrpX// mutant was 100-fold higher in the transgenic plants than in wild-type plants. This observation led the authors conclude that XopAA<sub>//Xoo//</sub> inhibits resistance to //Xoo//, which was probably caused by suppression of host PTI (Yamaguchi //et al.//, 2013). However, a //xopAA// knock-out strain of //Xoo// did not exhibit any defect in virulence (Yamaguchi //et al.//, 2013).
-=== In other plant pathogens/symbionts ===
+Expression of XopAA<sub>//Xoo//</sub> in //Arabidopsis// cells activated host immune responses, suggesting the presence of intracellular immune receptors that recognize XopAA (Yamaguchi //et al.//, 2013).
-===== Biological function =====
+//Xanthomonas oryzae// pv. //oryzicola// bacteria with a deletion of //xopAA// were found to cause enhanced virulence to a certain rice cultivar (Li //et al.//, 2015).
-=== How discovered? ===
+=== Localization ===
-=== (Experimental) evidence for being a T3E ===
+Unknown.
-=== Regulation ===
+=== Enzymatic function ===
-=== Phenotypes ===
+Unknown.
-=== Localization ===
+=== Interaction partners ===
-=== Enzymatic function ===
+A yeast two-hybrid experiment indicated that XopAA<sub>//Xoo//</sub> interacted with OsBAK1, an essential component of both microbe-associated molecular patterns (MAMPs) and BR receptors, suggesting that the virulent activity of XopAA is mediated by inhibition of OsBAK1 (Yamaguchi //et al.//, 2013).
-=== Interaction partners ===
 ===== Conservation =====
@@ Line 59: / Line 54: @@
 === In xanthomonads ===
-DNA hybridization experiments suggested that //xopAA// is highly specific to //Xee// (Morales //et al//., 2005).
+DNA hybridization experiments had suggested that //xopAA// might be highly specific to //Xee// (Morales //et al//., 2005). However, genomic comparisons showed that xopAA homologs are present in other xanthomonads, such as //X. hortorum//, //X. hydrangeae//, //X. oryzae//, //X. populi//, //X. translucens//, and //X. vasicola//.
 === In other plant pathogens/symbionts ===
+Yes (//Mesorhizobium//). Weak homology (ca 25% sequence identity) to proteins in //Erwinia// and //Pseudomonas// (HopAE1/HopW family)
 ===== References =====
@@ Line 69: / Line 67: @@
 Yamaguchi K, Nakamura Y, Ishikawa K, Yoshimura Y, Tsuge S, Kawasaki T (2013). Suppression of rice immunity by //Xanthomonas oryzae// type III effector Xoo2875. Biosci. Biotechnol. Biochem. 77: 796-801. DOI: [[https://doi.org/10.1271/bbb.120929|10.1271/bbb.120929]]
+===== Acknowledgements =====
+This fact sheet is based upon work from COST Action CA16107 EuroXanth, supported by COST (European Cooperation in Science and Technology).

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