Genetic control of chromatin structure 5' to the qa-x and qa-2 genes of Neurospora.

The roles of the qa-1F and qa-1S regulatory genes of Neurospora in modifying the chromatin structure of two qa structural genes have been studied by mapping DNase I hypersensitive sites in qa chromatin isolated from wild-type, qa-1F- (non-inducible) mutants, qa-1Sc (constitutive) mutants, qa-1S- (non-inducible) mutants, and from activator protein-independent mutants of qa-2 (qa-2ai). DNase I hypersensitive sites in the 5' region of the qa-x and qa-2 structural genes increase in number and sensitivity upon induction of transcription with quinic acid. Both qa-1F- and qa-1Sc mutations are associated with alterations in the DNase I sensitivity of the qa-x and qa-2 region, the latter mutations resulting in the common 5'-flanking region of these genes being accessible to DNase I. The qa-1F+ genotype is correlated with increased DNase I cleavage in the -200 to -88 region of qa-2, a region previously implicated in qa-1F regulation of RNA polymerase II access to the qa-2 promoters.