Expression of Chlamydia pneumoniae polymorphic membrane protein family genes

The genome of the obligate intracellular bacterium Chlamydia pneumoniae CWL 029 encodes a family of 21 proteins with predicted outer membrane localizat ion. These polymorphic membrane proteins (Pmps) are heterogeneous in both a mino acid sequence and predicted size but are unified by the conserved amin o acid motifs GGAI and FXXN repeated in the N-terminal half of each protein . Reverse transcriptase PCR analysis showed that all pmp genes are transcri bed. To determine whether all proteins are expressed, specific antisera wer e generated by immunization with mutually exclusive synthetic peptides repr esenting each of the 21 predicted Pmps. Each antiserum reacted with, and wa s typically immunospecific for, the corresponding peptide immunogen by enzy me-linked immunosorbent assay. Western blot analyses of purified elementary bodies showed that 11 of the 21 Pmps were detectable. Attempts to demonstr ate by Sarykosyl fractionation that the Pmps were localized to the outer me mbrane revealed that several of the Pmps were unstable and readily degraded . Analyses of additional C. pneumoniae strains showed that although some Pm ps are conserved, others vary between strains, in both molecular weight and level of expression.