Transcriptional analysis of the cyclophilin A gene (cypA) of Streptomyces chrysomallus.

Streptomyces chrysomallus produces a 17.5-kDa cyclophilin (CypA) as a major cytosolic protein. Northern blotting of total RNA from S. chrysomallus showed that cypA is transcribed as a monocistronic 500-nt transcript during the vegetative growth phase only. Consistently, Western blot analysis and enzyme activity determinations revealed a high level of CypA which declined drastically when cultures entered postexponential phase. Primer extension experiments revealed that cypA is transcribed as a leaderless transcript with the startpoint of transcription and translation being the same AUG codon. Analysis of -10 and -35 regions revealed an EohrdB-specific promoter consensus sequence in accordance with the observed transcription during vegetative growth of cultures. The leaderless cypA mRNA sequence between codons 5 to 12 shows complementarity to an internal antidownstream box of 16S rRNA of Streptomyces lividans. This may indicate a possible interaction of the leaderless cypA transcript with the 16S mRNA in translation initiation.