====== The Type III Effector XopAM from //Xanthomonas// ======

Author: [[https://www.researchgate.net/profile/Ralf-Koebnik|Ralf Koebnik]]
Expert reviewer: **WANTED!**

Class: XopAM\\
Family: XopAM\\
Prototype: XopXccR1/XC_3160 (//Xanthomonas campestris// pv. //campestris//; strain 8004) (Jiang //et al.//, 2009)\\
GenBank ID: [[https://www.ncbi.nlm.nih.gov/protein/AAY50204.1|AAY50204.1]] (2031 aa)\\
RefSeq ID: [[https://www.ncbi.nlm.nih.gov/protein/WP_012438997.1|WP_012438997.1]] (2049 aa)\\
3D structure: Unknown

===== Biological function =====

=== How discovered? ===

The //xopAM// gene in //X. campstris// pv. //campestris// strain 8004 (Xcc8004) was identified as a candidate T3E due to the presence of a PIP box (TTCGB-N<sub>15</sub>-TTCGB) within the upstream sequence of its putative translational start codon (Jiang //et al.//, 2009).
=== (Experimental) evidence for being a T3E ===

Using the HR-inducing domain AvrBs1<sub>59-445</sub> as a type-3 translocation reporter, the N-terminal region of XopAM<sub>Xcc8004</sub> was found to act as a type 3 secretion signal, since the translational reporter fusion triggered a //Bs1//-specific hypersensitive response in a //hrpF//- and //hpaB//-dependent manner (Jiang //et al.//, 2009).
=== Regulation ===

Using a promoterless β-glucuronidase (//gus//) gene as a transcriptional reporter, //xopAM// <sub>Xcc8004</sub> was found to be under control of HrpG and HrpX (Jiang //et al.//, 2009).
=== Phenotypes ===

Mutagenesis of type III effectors in //X. campestris// pv. //campestris// (//Xcc//) confirmed that //xopAM// functions as a second avirulence gene on plants of the Arabidopsis Col-0 ecotype (Guy //et al.//, 2013).

Deletion of //xopAM// from //Xcc// reduced its virulence in cruciferous crops but increased virulence in Arabidopsis (//Arabidopsis thaliana//) Col-0, indicating that XopAM may perform opposite functions depending on the host species (Xie //et al.//, 2023).
=== Localization ===

XopAM<sub>Xcc</sub> is a lipase that may target the cytomembrane (Xie //et al.//, 2023).
=== Enzymatic function ===

XopAM<sub>Xcc</sub> is a lipase that may target the cytomembrane and this activity might be enhanced by its membrane-targeted protein XOPAM-ACTIVATED RESISTANCE 1 (AMAR1) in Arabidopsis Col-0 (Xie //et al.//, 2023).
=== Interaction partners ===

Binding of XopAM<sub>Xcc</sub> to XOPAM-ACTIVATED RESISTANCE 1 (AMAR1) induced an intense hypersensitive response that restricted //Xcc// proliferation (Xie //et al.//, 2023).

===== Conservation =====

=== In xanthomonads ===

=== In other plant pathogens/symbionts ===

Yes (//e.g.//, //Pseudomonas syringae//, //Ralstonia solanacearum//) (Mukaihara //et al.//, 2004; Kvitko //et al.//, 2009)
===== References =====

Guy E, Genissel A, Hajri A, Chabannes M, David P, Carrere S, Lautier M, Roux B, Boureau T, Arlat M, Poussier S, Noël LD (2013). Natural genetic variation of //Xanthomonas campestris// pv. //campestris// pathogenicity on //Arabidopsis// revealed by association and reverse genetics. mBio 4: e00538-12. DOI: [[https://doi.org/10.1128/mBio.00538-12|10.1128/mBio.00538-12]]. Erratum in: MBio (2013) 4: e00978-13.

Jiang W, Jiang BL, Xu RQ, Huang JD, Wei HY, Jiang GF, Cen WJ, Liu J, Ge YY, Li GH, Su LL, Hang XH, Tang DJ, Lu GT, Feng JX, He YQ, Tang JL (2009). Identification of six type III effector genes with the PIP box in //Xanthomonas campestris// pv. //campestris// and five of them contribute individually to full pathogenicity. Mol. Plant Microbe Interact. 22: 1401-1411. DOI: [[https://doi.org/10.1094/MPMI-22-11-1401|10.1094/MPMI-22-11-1401]]

Kvitko BH, Park DH, Velásquez AC, Wei CF, Russell AB, Martin GB, Schneider DJ, Collmer A (2009). Deletions in the repertoire of //Pseudomonas syringae// pv. //tomato// DC3000 type III secretion effector genes reveal functional overlap among effectors. PLoS Pathog. 5: e1000388. DOI: [[https://doi.org/10.1371/journal.ppat.1000388|10.1371/journal.ppat.1000388]]

Mukaihara T, Tamura N, Murata Y, Iwabuchi M (2004). Genetic screening of Hrp type III-related pathogenicity genes controlled by the HrpB transcriptional activator in //Ralstonia solanacearum//. Mol. Microbiol. 54: 863-875. DOI: [[https://doi.org/10.1111/j.1365-2958.2004.04328.x|10.1111/j.1365-2958.2004.04328.x]]

Xie Q, Wei B, Zhan Z, He Q, Wu K, Chen Y, Liu S, He C, Niu X, Li C, Tang C, Tao J (2023). Arabidopsis membrane protein AMAR1 interaction with type III effector XopAM triggers a hypersensitive response. Plant Physiol., in press. DOI: [[https://doi.org/10.1093/plphys/kiad478|10.1093/plphys/kiad478]]