title: [Putative promoter region of type III effector gene avrAC(Xcc8004) in Xanthomonas campestris pv. campestris].
abstract: OBJECTIVE
  Xanthomonas campestris pv. campestris (Xcc) is the cause agent of black rot of crucifers. Xcc uses type III secretion system (T3SS) to deliver T3SS effectors (T3SEs) directly into host cells, where they play important roles in pathogenesis. Many identified T3SEs genes contain plant-inducible promoter(PIP) box and -10 box in their promoter regions. However, the relation among PIP-box, -10 box and -10 region, -35 region of the classic promoter is unclear, and the conservative characteristic of -10 box sequence is hardly reported. The aim of this study was to analyze the putative promoter region of T3SE gene avrAC(Xcc8004).
  
  
  METHODS
  Through 5' RACE, the transcriptional start site of avrAC(Xcc8004) was identified. Fusion PCR was introduced to generate the site-mutagenesis of -10 box for constructing the GUS fusion report strains.
  
  
  RESULTS
  The 5' RACE results indicate that the transcription start site was A. After analysis, we found that -35 region was located 8 bp downstream of PIP-box, and -10 box was exactly overlapped with -10 region. The whole motif of PIP-box, -35 region, and -10 box was then counted as: TTCAC-N15-TTCGC-N8-TTGATG-N18-TACGTT. The GUS assay results demonstrate that the site-mutagenesis of -10 box caused a higher expression of avrAC(Xcc8004). The GUS activities in the mutant strains delta hrpX and delta hrpG were significantly lower than that in the wild type Xcc strains.
  
  
  CONCLUSIONS
  PIP-box is tandem with -35 region, -10 box is just the same as -10 region, -10 box is important for the transcription of avrAC(Xcc8004), and HrpG and HrpX activate the expression of avrAC(X8004), despite of -10 box site-mutagenesis.
authors.forename: Guofeng
authors.initials: G
authors.lastname: Jiang
authors.forename: Qiuju
authors.initials: Q
authors.lastname: Wu
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Liang
authors.forename: Lichao
authors.initials: L
authors.lastname: Yang
authors.forename: Liyan
authors.initials: L
authors.lastname: Yang
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Wu
authors.forename: Bole
authors.initials: B
authors.lastname: Jiang
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D016959:Xanthomonas campestris / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins