title: Comparative analysis of the XopD type III secretion (T3S) effector family in plant pathogenic bacteria.
abstract: XopD is a type III effector protein that is required for Xanthomonas campestris pathovar vesicatoria (Xcv) growth in tomato. It is a modular protein consisting of an N-terminal DNA-binding domain, two ethylene-responsive element binding factor-associated amphiphilic repression (EAR) transcriptional repressor motifs and a C-terminal small ubiquitin-related modifier (SUMO) protease. In tomato, XopD functions as a transcriptional repressor, resulting in the suppression of defence responses at late stages of infection. A survey of available genome sequences for phytopathogenic bacteria revealed that XopD homologues are limited to species within three genera of Proteobacteria--Xanthomonas, Acidovorax and Pseudomonas. Although the EAR motif(s) and SUMO protease domain are conserved in all XopD-like proteins, variation exists in the length and sequence identity of the N-terminal domains. Comparative analysis of the DNA sequences surrounding xopD and xopD-like genes led to revised annotation of the xopD gene. Edman degradation sequence analysis and functional complementation studies confirmed that the xopD gene from Xcv encodes a 760-amino-acid protein with a longer N-terminal domain than previously predicted. None of the XopD-like proteins studied complemented Xcv ΔxopD mutant phenotypes in tomato leaves, suggesting that the N-terminus of XopD defines functional specificity. Xcv ΔxopD strains expressing chimeric fusion proteins containing the N-terminus of XopD fused to the EAR motif(s) and SUMO protease domain of the XopD-like protein from X. campestris pathovar campestris strain B100 were fully virulent in tomato, demonstrating that the N-terminus of XopD controls specificity in tomato.
authors: Department of Biology, Stanford University, Stanford, CA 94305-5020, USA.
authors: Jung-Gun
authors: JG
authors: Kim
authors: Kyle W
authors: KW
authors: Taylor
authors: Mary Beth
authors: MB
authors: Mudgett
mesh_terms: D001419:Bacteria / Q000378:metabolism* / Q000472:pathogenicity*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000382:microbiology; D010802:Phylogeny; D010944:Plants / Q000382:microbiology*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000737:chemistry / Q000378:metabolism; D016959:Xanthomonas campestris / Q000378:metabolism / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D025841:Small Ubiquitin-Related Modifier Proteins