RNA polymerase induces DNA bending at yeast mitochondria] promoters

Yeast mitochondrial RNA polymerase can bind specifically to promoter-containing DNA fragments in vitro as detected by DNAse I or methidiumpropyl-EDTA. Fe(II) protection assays and gel retardation experiments. Retardation of RNA polymerase-DNA complexes was most pronounced when the promoter was located in the middle of a DNA fragment and was diminished when RNA polymerase was bound near one of the ends. This indicates that upon RNA polymerase-binding the DNA undergoes a conformational change which is most likely a bend. The degree of introduced bending correlated with the efficiency of transcription and promoter-binding in a series of promoter mutants, suggesting that bending is a functional event during promoter utilisation.