Department of Biotechnology, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Biochem Biophys Res Commun. 2013 Aug 16;438(1):26-31. doi: 10.1016/j.bbrc.2013.07.013. Epub 2013 Jul 13.
Damaged DNA-binding protein (DDB) is a heterodimer composed of two subunits, p127 and p48, which have been designated DDB1 and DDB2, respectively. DDB2 recognizes and binds to UV-damaged DNA during nucleotide excision repair. Here, we demonstrated that DDB2 was SUMOylated in a UV-dependent manner, and its major SUMO E3 ligase was PIASy as determined by RNA interference-mediated knockdown. The UV-induced physical interaction between DDB2 and PIASy supported this notion. PIASy knockdown reduced the removal of cyclobutane pyrimidine dimers (CPDs) from total genomic DNA, but did not affect that of 6-4 pyrimidine pyrimidone photoproducts (6-4PPs). Thus, DDB2 plays an indispensable role in CPD repair, but not in 6-4PP repair, which is consistent with the observation that DDB2 was SUMOylated by PIASy. These results suggest that the SUMOylation of DDB2 facilitates CPD repair.
受损的 DNA 结合蛋白（DDB）是一种由两个亚基组成的异二聚体，分别命名为 DDB1 和 DDB2。DDB2 在核苷酸切除修复过程中识别和结合 UV 损伤的 DNA。在这里，我们证明了 DDB2 以 UV 依赖的方式被 SUMO 化，其主要的 SUMO E3 连接酶是 PIASy，这是通过 RNA 干扰介导的敲低确定的。UV 诱导的 DDB2 和 PIASy 之间的物理相互作用支持了这一观点。PIASy 的敲低减少了总基因组 DNA 中环丁烷嘧啶二聚体（CPD）的去除，但不影响 6-4 嘧啶嘧啶酮光产物（6-4PP）的去除。因此，DDB2 在 CPD 修复中起着不可或缺的作用，但在 6-4PP 修复中则不然，这与 DDB2 被 PIASy SUMO 化的观察结果一致。这些结果表明，DDB2 的 SUMO 化促进了 CPD 修复。
