No strict alignment is required between a transcriptional activator binding site and the 'TATA box' of a yeast gene

Abstract

GAL4 is a transcriptional activator of the galactose metabolism genes in the yeast Saccharomyces cerevisiae. We show that GAL4 expressed in yeast activated transcription equally well when a single GAL4 binding site was placed at any of nine positions upstream of the GAL1 (galactokinase gene) 'TATA box'. We chose a sufficient number of positions for the binding site to ensure that, in several of these positions, GAL4 was on the opposite of the DNA helix with respect to the TATA box. Smaller GAL4 derivatives were similar to wild-type GAL4 in that they also activated transcription in a manner independent of the side of the DNA helix they bound with respect to the TATA box. Unlike wild-type GAL4, however, these smaller GAL4 derivatives activated transcription better when we placed a binding site progressively closer to the TATA box over a distance of 34 base pairs.