Hrp pathogenicity island of Erwinia amylovora and identification of three novel genes required for systemic infection

• Published in: Molecular plant pathology 2005-03, Vol.6 (2), p.125-138
• Main Authors: Oh, C.S, Kim, J.F, Beer, S.V
• Format: Article
• Language: English
• Subjects: amidinotransferases; apples; avirulence proteins; Bacterial plant pathogens; bacterial proteins; Biological and medical sciences; biosynthesis; blight; chromosomes; Enterobacteriaceae; Erwinia amylovora; Fundamental and applied biological sciences. Psychology; Malus domestica; molecular sequence data; nucleotide sequences; open reading frames; Pantoea agglomerans pv. gypsophilae; Pantoea stewartii subsp. stewartii; pathogenicity islands; Pectobacterium carotovorum subsp. atrosepticum; Pectobacterium chrysanthemi; phaseolotoxin; Phytopathology. Animal pests. Plant and forest protection; plant pathogenic bacteria; Pseudomonas syringae; sequence analysis; Systematics. Structure, properties and multiplication. Genetics; virulence; Xanthomonas campestris; Yersinia pseudotuberculosis
• ISSN: 1464-6722; 1364-3703
• DOI: 10.1111/j.1364-3703.2005.00269.x

SUMMARY Sequence analysis of the region bordering the hrp/dsp gene cluster of Erwinia amylovora strain Ea321, which causes fire blight, revealed characteristics of pathogenicity islands (PAIs). Included are genes for a phage integrase, a tRNAPhe, several orthologues of genes of YAPI, a PAI of Yersinia pseudotuberculosis, and several putative virulence genes with HrpL‐dependent promoter motifs. The island is designated the Hrp PAI of E. amylovora. It is comprised of a chromosomal region of c. 62 kb with 60 open reading frames (ORFs). Comparison of the Hrp PAI of E. amylovora with those of four closely related bacteria showed that orfB, a homologue of avrBsT of Xanthomonas campestris pv. vesicatoria, and orfA, its putative chaperone gene, are present only in the Hrp PAI of E. amylovora. As regions flanking the hrp/dsp gene cluster are quite diverse, addition and deletion may have occurred during divergent evolution of the five bacteria. Among ORFs of the PAI of Ea321, three new HrpL‐dependent genes were identified. Because they are required for full virulence in apple, they were designated hsvC, hsvB and hsvA (hrp‐associated systemic virulence). They encode a homologue of an amidinotransferase for phaseolotoxin biosynthesis and homologues of a nikkomycin‐biosynthetic protein of Pseudomonas syringae.