The Type III Effector XopJ7 from //Xanthomonas//

Author: Anna Passelergue
Internal reviewer: Ralf Koebnik

Class: XopJ
Family: XopJ7
Prototype: E4A48_06420 (Xanthomonas cerealis pv. cerealis, strain 01)
GenBank ID: QDI05802.1 (493 aa)
RefSeq ID: WP_185910725.1 (389 aa). Attention: The RefSeq sequence is too short because 104 codons encoding the N-terminal region, including the type III secretion signal, are missing.
3D structure: Unknown

XopJ7 was discovered as an ORF that is encoded downstream of a PIP box and a properly spaced ‐10 promoter motif (TTCGB‐N₁₅ ‐TTCGB‐N_30–32 ‐YANNNT) (Passelergue, 2025). Additional evidence came from the presence of conserved myristoylation and palmitoylation signals (Nimchuk et al., 2000; Thieme et al., 2007), which were in frame with the ORF. Based on this observation, the translation initiation codon is likely 104 codons upstream of the annotated codon for the locus E4A48_RS06415.

XopJ7 was shown to have a functional type III secretion signal using a reporter fusion with AvrBs1 (Zhao et al., 2013).

The presence of a PIP box and a properly spaced ‐10 promoter motif (TTCGB‐N₁₅ ‐TTCGB‐N_30–32 ‐YANNNT) suggests that the xopJ7 gene is under control of HrpG and HrpX (Wengelnik & Bonas, 1996; Wengelnik et al., 1996; Koebnik et al., 2006).

Unknown.

The presence of conserved myristoylation and palmitoylation signals at the N terminus suggests that the protein is localized to the plasma membrane in the plant host cell (Nimchuk et al., 2000; Thieme et al., 2007).

Unknown.

Unknown.

Yes (e.g., X. euvesicatoria, X. campestris, X. hortorum). =

Yes (e.g., Acidovorax/Paracidovorax ssp., Burkholderia/Paraburkholderia ssp; remote homologs in Ralstonia ssp.].

Koebnik R, Krüger A, Thieme F, Urban A, Bonas U (2006). Specific binding of the Xanthomonas campestris pv. vesicatoria AraC-type transcriptional activator HrpX to plant-inducible promoter boxes. J. Bacteriol. 188: 7652-7660. DOI: 10.1128/JB.00795-06

Nimchuk Z, Marois E, Kjemtrup S, Leister RT, Katagiri F, Dangl JL (2000). Eukaryotic fatty acylation drives plasma membrane targeting and enhances function of several type III effector proteins from Pseudomonas syringae. Cell 101: 353-363. DOI: 10.1016/s0092-8674(00)80846-6

Passelergue A (2025). Discovery of eight type III effector genes harboring the PIP box in clade-I xanthomonads. Master's thesis, Université de Montpellier, France.

Thieme F, Szczesny R, Urban A, Kirchner O, Hause G, Bonas U (2007). New type III effectors from Xanthomonas campestris pv. vesicatoria trigger plant reactions dependent on a conserved N-myristoylation motif. Mol. Plant Microbe Interact. 20: 1250-1261. DOI: 10.1094/MPMI-20-10-1250

Wengelnik K, Bonas U (1996). HrpXv, an AraC-type regulator, activates expression of five of the six loci in the hrp cluster of Xanthomonas campestris pv. vesicatoria. J. Bacteriol. 178: 3462-3469. DOI: 10.1128/jb.178.12.3462-3469.1996

Wengelnik K, Van den Ackerveken G, Bonas U (1996). HrpG, a key hrp regulatory protein of Xanthomonas campestris pv. vesicatoria is homologous to two-component response regulators. Mol. Plant Microbe Interact. 9: 704-712. DOI: 10.1094/mpmi-9-0704

Zhao S, Mo WL, Wu F, Tang W, Tang JL, Szurek B, Verdier V, Koebnik R, Feng JX (2013). Identification of non-TAL effectors in Xanthomonas oryzae pv. oryzae Chinese strain 13751 and analysis of their role in the bacterial virulence. World J. Microbiol. Biotechnol. 29: 733-744. DOI: 10.1007/s11274-012-1229-5

This fact sheet is based upon work from COST Action CA16107 EuroXanth, supported by COST (European Cooperation in Science and Technology).