Open AccessThe Hrp pathogenicity island of Erwinia amylovora and identification of three novel genes required for systemic infection ‡
Author(s) -
OH CHANGSIK,
KIM JIHYUN F.,
BEER STEVEN V.
Publication year - 2005
Publication title -
molecular plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.945
H-Index - 103
eISSN - 1364-3703
pISSN - 1464-6722
DOI - 10.1111/j.1364-3703.2005.00269.x
Subject(s) - biology , orfs , erwinia , gene , virulence , pathogenicity island , genetics , pseudomonas syringae , yersinia pseudotuberculosis , microbiology and biotechnology , gene cluster , open reading frame , xanthomonas campestris , peptide sequence
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 tRNA Phe , 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 ( h rp ‐associated s ystemic v irulence). They encode a homologue of an amidinotransferase for phaseolotoxin biosynthesis and homologues of a nikkomycin‐biosynthetic protein of Pseudomonas syringae .