Chromatin structure of the 5' flanking region of the yeast LEU2 gene.

The chromatin structure of the LEU2 gene and its flanks has been studied by means of nuclease digestion, both with micrococcal nuclease and DNase I. The gene is organized in a array of positioned nucleosomes. Within the promoter region, the nucleosome positioning places the regulatory sequences, putative TATA box and upstream activator sequence outside the nucleosomal cores. The tRNA3Leu gene possesses a characteristic structure and is protected against nucleases. Most of the 5' flank is sensitive to DNase I digestion, although no clear hypersensitive sites were found. The chromatin structure is independent of either the transcriptional state of the gene or the chromosomal or episomal location. Finally, in the plasmid pJDB207, which lacks most of the promoter, we have found that the chromatin structure of the coding region is similar to that of the wild-type allele.