Chemical synthesis of oxanine-contained oligodeoxynucleotides.

Oxanine, one of major damaged product from deamination of guanine base mediated by NO or HNO2-induced nitrosative reaction, has been considered as a genotoxic lesion. To analyze the biophysical properties of oxanine in context of oligodeoxynucleotide, the chemical incorporation of 2'-deoxyoxanosine (dOxo, nucleoside form of oxanine) into oligodeoxynucleotide is required. Here, we developed the chemical synthesis procedures of dimethoxytritylated dOxo-phosphoramidite (DMT-dOxo-amidite) and oxanine-contained oligonucleotide.

Differential transcriptional regulation of two distinct S-adenosylmethionine synthetase genes (SAM1 and SAM2) of Saccharomyces cerevisiae.

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.