THE FINM PROMOTER AND THE TRAM PROMOTER ARE THE PRINCIPAL PROMOTERS OF THE TRAM GENE OF THE ANTIBIOTIC-RESISTANCE PLASMID R100

finP multicopy repression and traJ multicopy derepression indicate tha t the ratio of sense to antisense transcripts is important in the regu lation of R100 conjugation. The extension of R100 traM transcripts int o traJ shows that promoters in traM can affect this ratio, making the regulation of traM transcription important in the regulation of R100 c onjugation, Since R100 traM, traY and tral proteins bind to the traM p romoter region, we examined traM transcription in R100-1 traM, tray an d tral mutants and compared it with traM transcription in both R100-1 and R100. We verified that the traM and finM promoters provide virtual ly ail the transcripts originating in the R100-1 traM gene. When eithe r is deleted, as in VAR22 or VAR30, the remaining promoter is highly a ctive. We show here that traY positively regulates R100-1 traM transcr iption, as has been found for F. We found that tral did not regulate R 100-1 traM transcription. The measured activity of the native R100 tra M promoter was 12% of that in R100-1, whereas the native R100 finM pro moter was 45% of that in R100-1. These data and data from the R100-1 t ray and tral mutants show that the activities of the two promoters Var ied independently.