[Show abstract][Hide abstract] ABSTRACT: Expression of a number of genes encoding enzymes involved in phospholipid biosynthesis in yeast Saccharomyces cerevisiae is known to be repressed on the addition of myo-inositol and choline to the culture medium (inositol-choline regulation). All genes subject to this inositol-choline regulation have an octamer sequence 5'-CATRTGAA-3' in their upstream regions and those octamer sequences play an important role in this regulation. To confirm the role of the octamer sequence further, we studied the transcriptional regulation of two distinct S-adenosylmethionine synthetase genes (SAM1 and SAM2) of S. cerevisiae. Quantitative RT-PCR analysis showed that only the SAM2 gene was subject to the inositol-choline regulation, consistent with the fact that only the SAM2 gene has two octamer sequences in its upstream region. Furthermore, functional promoter analysis revealed that the proximal octamer sequence of the SAM2 gene has an essential role for this regulation.
[Show abstract][Hide abstract] ABSTRACT: The design of molecules that target desired DNA sequences has been one of the major challenges in the field of molecular recognition. We report here a general strategy for defining the sequence-preference of DNA-binding short peptide by using its heterodimer. Our method successfully identified specific sequences of short peptides derived from native DNA-binding proteins. The usefulness of this approach has been demonstrated by identifying preferred DNA targets for a peptide composed only of D-amino acids.