Inhibition of DNA polymerase eta by oxetanocin derivatives.

DNA polymerase eta is recently found as a responsible gene product of xeroderma pigmentosum variant. Differently from other eukaryotic DNA polymerases, such as alpha, beta or gamma, eta polymerase is categorized in Y family. Specific inhibitors for DNA polymerases are useful tools to study the exact role of enzyme in the living cells, however, the inhibitor for DNA polymerase eta has not been developed. We examined the inhibitory effects of several sugar-modified nucleotide analogs on DNA polymerase eta. The arabinonucleotides (araCTP), dideoxynucleotides (ddTTP) and 3'-modified nucleotides (3'-dCTP and 3'-azidothymidine tri-phosphate) did not show any inhibitory effect on DNA polymerase eta. On the other hand, the oxetanocin derivatives those have the oxetane ring as a sugar moiety, OXT-GTP and OXT-ATP, strongly inhibited this polymerase. These results suggest that DNA polymerase eta has a unique recognition mode against the sugar moiety of nucleotide compared with other eukaryotic nucleotide polymerases.