Crystal structure of the type III effector XopAI from Xanthomonas axonopodis pv. citri in space group P43212

Experimental Data Snapshot

  • Resolution: 2.01 Å
  • R-Value Free: 0.195 
  • R-Value Work: 0.166 
  • R-Value Observed: 0.167 

wwPDB Validation   3D Report Full Report

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Crystal Structure-Based Exploration of Arginine-Containing Peptide Binding in the ADP-Ribosyltransferase Domain of the Type III Effector XopAI Protein.

Liu, J.H.Yang, J.Y.Hsu, D.W.Lai, Y.H.Li, Y.P.Tsai, Y.R.Hou, M.H.

(2019) Int J Mol Sci 20

  • DOI: https://doi.org/10.3390/ijms20205085
  • Primary Citation of Related Structures:  
    6K93, 6K94, 6KLY

  • PubMed Abstract: 

    Plant pathogens secrete proteins called effectors into the cells of their host to modulate the host immune response against colonization. Effectors can either modify or arrest host target proteins to sabotage the signaling pathway, and therefore are considered potential drug targets for crop disease control. In earlier research, the Xanthomonas type III effector XopAI was predicted to be a member of the arginine-specific mono-ADP-ribosyltransferase family. However, the crystal structure of XopAI revealed an altered active site that is unsuitable to bind the cofactor NAD+, but with the capability to capture an arginine-containing peptide from XopAI itself. The arginine peptide consists of residues 60 through 69 of XopAI, and residue 62 (R62) is key to determining the protein-peptide interaction. The crystal structure and the molecular dynamics simulation results indicate that specific arginine recognition is mediated by hydrogen bonds provided by the backbone oxygen atoms from residues W154, T155, and T156, and a salt bridge provided by the E265 sidechain. In addition, a protruding loop of XopAI adopts dynamic conformations in response to arginine peptide binding and is probably involved in target protein recognition. These data suggest that XopAI binds to its target protein by the peptide-binding ability, and therefore, it promotes disease progression. Our findings reveal an unexpected and intriguing function of XopAI and pave the way for further investigation on the role of XopAI in pathogen invasion.

  • Organizational Affiliation

    Department of Life Science, NCHU, Taichung 40227, Taiwan. mhho@nchu.edu.tw.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Type III effector XopAI316Xanthomonas citriMutation(s): 0 
Gene Names: XopAIXAC3230
Find proteins for A0A0U5GCU5 (Xanthomonas citri pv. citri)
Explore A0A0U5GCU5 
Go to UniProtKB:  A0A0U5GCU5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A0U5GCU5
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.01 Å
  • R-Value Free: 0.195 
  • R-Value Work: 0.166 
  • R-Value Observed: 0.167 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 73.05α = 90
b = 73.05β = 90
c = 114.06γ = 90
Software Package:
Software NamePurpose
iMOSFLMdata reduction
pointlessdata scaling

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Ministry of Science and Technology (Taiwan)TaiwanMOST 106-2313-B-005-029

Revision History  (Full details and data files)

  • Version 1.0: 2019-08-21
    Type: Initial release
  • Version 1.1: 2019-10-30
    Changes: Data collection, Database references