Productive and abortive initiation of transcription in vitro at the lac UV5 promoter

Abstract

The rates of productive and abortive initiation of transcription in vitro at the lac UV5 promoter [Escherichia coli] were determined and compared to values determined for phage .lambda. and T7 promoters. The rate constants for productive initiation of lac transcript are consistently lower over a range of low to moderate concentration of initiating ATP. Abortive initiation of lac dinucleoside tetraphosphate is also slower at low to moderate concentrations of ATP. These data demonstrate the existence of significant differences in initiation rate among promoters. These differences may be a consequence of the initial mRNA sequences and extents of RNA polymerase cycling during initiation of promoter-specific transcription.