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 sho wed that cypA is transcribed as a monocistronic 500-nt transcript during th e vegetative growth phase only. Consistently, Western blot analysis and enz yme activity determinations revealed a high level of CypA which declined dr astically when cultures entered postexponential phase. Primer extension exp eriments revealed that cypA is transcribed as a leaderless transcript with the startpoint of transcription and translation being the same AUG codon. A nalysis of -10 and -35 regions revealed an E sigma(hrdB)-specific promoter consensus sequence in accordance with the observed transcription during veg etative growth of cultures. The leaderless cypA mRNA sequence between codon s 5 to 12 shows complementarity to an internal antidownstream box of 16S rR NA of Streptomyces lividans. This may indicate a possible interaction of th e leaderless cypA transcript with the 16S mRNA in translation initiation. ( C) 1999 Federation of European Microbiological Societies. Published by Else vier Science B.V. All rights reserved.