title: Remarkable sequence relatedness in the DNA encoding the major outer membrane protein of Chlamydia psittaci (koala type I) and Chlamydia pneumoniae.
abstract: DNA encoding the major outer membrane protein (MOMP) of the koala type-I strain of Chlamydia psittaci (pathogen responsible for blindness and infertility in koalas) was cloned and sequenced. Comparison with momp gene sequences from other chlamydial species revealed a remarkable degree of homology (> 97%) with that of the human pathogen, Chlamydia pneumoniae. In comparison, the sequence only shared 75% DNA sequence homology with other C. psittaci members and 69% homology with C. trachomatis. The open reading frame consisted of 1167 bp encoding a 389-amino acid (aa) pre-MOMP including a leader sequence of 23 aa, similar to the C. pneumoniae gene. These genes were closely related even within the four variable domains (86-100% homology). Specific antibodies were capable of distinguishing between koala type I and C. pneumoniae. This very high degree of relatedness between C. pneumoniae, a human pathogen, and an individual strain of C. psittaci in the momp gene raises further questions on the host specificity, classification and evolutionary relationships of the different chlamydial species.
authors.affiliation: Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, Brisbane, Australia.
authors.forename: A A
authors.initials: AA
authors.lastname: Girjes
authors.forename: F N
authors.initials: FN
authors.lastname: Carrick
authors.forename: M F
authors.initials: MF
authors.lastname: Lavin
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001483:Base Sequence; D016993:Chlamydophila pneumoniae / Q000235:genetics*; D002691:Chlamydophila psittaci / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; D021382:Protein Sorting Signals