Multiple tandem promoters of the major outer membrane protein gene (omp1) of Chlamydia psittaci.

The transcription of omp1, the gene encoding the major outer membrane protein, was studied for two strains of Chlamydia psittaci, guinea pig inclusion conjunctivitis (GPIC) and mouse pneumonitis (Mn). The transcriptional initiation sites for the omp1 of each strain were mapped by S1 nuclease and primer extension analyses. Three different sizes of omp1 transcripts were observed for GPIC and four were observed for Mn. The production of these transcripts appeared to be the consequence of multiple tandem promoters. The order in which the omp1 RNA transcripts appeared during the growth cycle of the C. psittaci strains was found to differ from that of C. trachomatis.