The nucleotide sequence of the 60 kDa cysteine rich outer membrane protein of Chlamydia pneumoniae strain IOL-207.

Members of the species chlamydia are characterised by their obligate intracellular life cycle. The genus comprises three species; Chlamydia trachomatis, Chlamydia psittaci and Chlamydia pneumoniae. C. pneumoniae causes acute respiratory infections in humans. This organism has only recently been shown to warrant its own species classification within the chlamydial genus based on immunological, ultrastructural and DNA hybridization studies (1). As yet no other host has been reported for C. pneumoniae. The complete nucleotide sequence for the 60kDa cysteine rich outer membrane protein (CrP) of Chlamydia pneumoniae was determined using dideoxy chain termination sequencing on double stranded plasmid DNA. The sequence shows 71 %, 72 % and 85% homology to the C. trachomatis serovars LI and B and the C. psittaci 60kDa CrP genes respectively. The structural gene consists of an open reading frame of 1668 base pairs, (Fig. 1) starting with ATG at 113 bp and ending with a TAA termination codon. The DNA sequence contained two hairpin loop structures, 13 bp and 57 bp downstream of its presumed termination codon With free energies of -37.4 kcal mol ' and 12.2 kcal mol ' respectively. The first hairpin loop was predicted to be more stable but this structure was not characteristic of a Rhoindependent RNA transcriptional terminator (2). The second hairpin loop structure found 57 bp from the termination codon was characteristic of a Rho-independent terminator having four downstream thymine residues. This dual termination structure was also present in the 60kDa CrP genes of C. trachomatis serovars LJ and B (3).