title: Promoter analysis of macrophage- and tick cell-specific differentially expressed Ehrlichia chaffeensis p28-Omp genes.
abstract: BACKGROUND
  Ehrlichia chaffeensis is a rickettsial agent responsible for an emerging tick-borne illness, human monocytic ehrlichiosis. Recently, we reported that E. chaffeensis protein expression is influenced by macrophage and tick cell environments. We also demonstrated that host response differs considerably for macrophage and tick cell-derived bacteria with delayed clearance of the pathogen originating from tick cells.
  
  
  RESULTS
  In this study, we mapped differences in the promoter regions of two genes of p28-Omp locus, genes 14 and 19, whose expression is influenced by macrophage and tick cell environments. Primer extension and quantitative RT-PCR analysis were performed to map transcription start sites and to demonstrate that E. chaffeensis regulates transcription in a host cell-specific manner. Promoter regions of genes 14 and 19 were evaluated to map differences in gene expression and to locate RNA polymerase binding sites.
  
  
  CONCLUSIONS
  RNA analysis and promoter deletion analysis aided in identifying differences in transcription, DNA sequences that influenced promoter activity and RNA polymerase binding regions. This is the first description of a transcriptional machinery of E. chaffeensis. In the absence of available genetic manipulation systems, the promoter analysis described in this study can serve as a novel molecular tool for mapping the molecular basis for gene expression differences in E. chaffeensis and other related pathogens belonging to the Anaplasmataceae family.
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA. lpeddire@vet.k-state.edu
authors.forename: Lalitha
authors.initials: L
authors.lastname: Peddireddi
authors.forename: Chuanmin
authors.initials: C
authors.lastname: Cheng
authors.forename: Roman R
authors.initials: RR
authors.lastname: Ganta
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D002874:Chromosome Mapping; D004285:Dogs; D018469:Ehrlichia chaffeensis / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008264:Macrophages / Q000382:microbiology*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000235:genetics; D013045:Species Specificity; D013987:Ticks / Q000382:microbiology*; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: D001425:Bacterial Outer Membrane Proteins; D012329:RNA, Bacterial