A STRAND-SPECIFIC ENDONUCLEOLYTIC ACTIVITY WITH DNA SITE PREFERENCE FOR CLEAVAGE IN CHLAMYDIA-TRACHOMATIS

Endonucleolytic activity was detected in high-salt extracts of Chlamyd ia trachomatis cell lysates. This nucleolytic activity showed specific ity for one strand of a PCR fragment containing the strong chlamydial promoter that regulates synthesis of two short plasmid-specified RNAs. Strand specificity aas also observed with supercoiled DNA containing the same region; once again, the same strand was cleaved. The sensitiv e strand is the nontemplate strand for two short transcripts which ini tiate at the same nucleotide. Alignment of sequences on either side of the nick sites revealed a consensus which may be required for recogni tion of the enzymatic activity.