Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/1999
Publication Date: N/A
Interpretive Summary: A recent study of ribosomal RNA genes and phenotypic traits indicates that the order Chlamydiales contains at least four distinct bacterial families, including Chlamydiaceae, Simkaniaceae, Parachlamydiaeae, and Waddliaceae. Chlamydiaceae has nine species, and most of these species cause widespread disease that can be fatal in humans or livestock. Additional markers are needed to facilitate identification of these species, and in this study on such possible marker, rnpB, was examined. Sequence, functional, and structural characteristics were identified in rnpB that were unique for the family Chlamydiales. The rnpB sequences from Chlamydiaceae species could be readily distinguished from one another and were highly conserved within species. These findings suggest that rnpB will be an appropriate target for nucleic acid based differentiation of the species and families in Chlamydiales.
Technical Abstract: The sequence of the RNase P RNA gene (rnpB) was determined for 60 strains representing all nine species in the Chlamydiaceae family and for the related Chlamydiales species, Parachlamydia acanthamoebae and Simkania negevensis. These sequences were used to infer evolutionary relationships among the Chlamydiaceae. The analysis separated Chlamydophila and Chlamydia into two lineages, with Chlamydophila forming three distinct clusters: the Chlamydophila pneumoniae strains, the Chlamydophila pecorum strains, and a third cluster comprising the species Chlamydophila psittaci, Chlamydophila abortus, Chlamydophila caviae and Chlamydophila felis. The Chlamydia line of descent contained two clusters, with the Chlamydia suis strains distinctly separated from strains of Chlamydia trachomatis and Chlamydia muridarum. This analysis indicated that the rnpB sequence and structure are distinctive markers for species in the Chlamydiaceae. We also demonstrated that the Rnase P RNA derived from C. trachomatis is able to cleave a tRNA precursor in the absence of protein. Our findings are discussed in relation to the structure of Chlamydia Rnase P RNA.