title: Characterization of the rRNA genes of Ehrlichia chaffeensis and Anaplasma phagocytophila.
abstract: The rRNA genes of Ehrlichia chaffeensis and Anaplasma phagocytophila have been analyzed. The 16S rRNA genes were previously characterized for both of these agents. Southern hybridization was used to show that there are single copies of both the 16S and 23S rRNA genes in the genomes of each organism, and that the 16S rRNA genes were upstream from the 23S rRNA genes by at least 16 and 11 Kb for E. chaffeensis and A. phagocytophila, respectively. PCR amplification and gene walking was used to sequence the 23S and 5S rRNA genes, and show that these genes are contiguous and are likely expressed as a single operon. The level of homology between the E. chaffeensis and A. phagocytophila 23S and 5S rRNA genes, and 23S-5S spacers, was 91.8, 81.5, and 40%, respectively. To confirm the hybridization data, genome walking was used to sequence downstream of the 16S rRNA genes, and although no tRNA genes were identified, open reading frames encoding homologues of the Escherichia coli succinate dehydrogenase, subunit C, were found in both E. chaffeensis and A. phagocytophila. Phylogenetic analysis using the 23S rRNA gene suggests that reorganization of the phylum Proteobacteria by division of the class Alphaproteobacteria into two separate subclasses, may be appropriate.
authors.affiliation: Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. rfm2@cdc.gov
authors.forename: Robert F
authors.initials: RF
authors.lastname: Massung
authors.forename: Kemba
authors.initials: K
authors.lastname: Lee
authors.forename: Michael
authors.initials: M
authors.lastname: Mauel
authors.forename: Asiya
authors.initials: A
authors.lastname: Gusa
mesh_terms: D000595:Amino Acid Sequence; D000709:Anaplasma / Q000235:genetics*; D004269:DNA, Bacterial / Q000032:analysis; D021901:DNA, Intergenic; D018469:Ehrlichia chaffeensis / Q000235:genetics*; D018628:Gene Dosage; D005798:Genes, Bacterial; D020459:Genes, rRNA; D008969:Molecular Sequence Data; D009876:Operon; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment
chemical_list: D004269:DNA, Bacterial; D021901:DNA, Intergenic