RESUMO
Thymine DNA glycosylase (TDG) is a base excision repair enzyme that interacts with the small ubiquitin-related modifier (SUMO)-targeted ubiquitin E3 ligase RNF4 and functions in the active DNA demethylation pathway. Here we showed that both SUMOylated and non-modified forms of endogenous TDG fluctuated during the cell cycle and in response to drugs that perturbed cell cycle progression, including hydroxyurea and nocodazole. Additionally, we detected a SUMOylation-independent association between TDG and RNF4 in vitro as well as in vivo, and observed that both forms of TDG were efficiently degraded in RNF4-depleted cells when arrested at S phase. Our findings provide insights into the in vivo dynamics of TDG SUMOylation and further clarify the TDG-RNF4 interaction.
Assuntos
Metilação de DNA , Proteínas Nucleares/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Sumoilação , Timina DNA Glicosilase/metabolismo , Fatores de Transcrição/metabolismo , Ciclo Celular/efeitos dos fármacos , Células Cultivadas , Humanos , Hidroxiureia/farmacologia , Mutação , Nocodazol/farmacologia , Timina DNA Glicosilase/genéticaRESUMO
A hallmark of small ubiquitin-related modifier (SUMO) is the production of a C-terminal tail containing diglycines (GGs), which are believed to be required for SUMOylation. Whether GGs are required components in SUMOylation remains unanswered experimentally. In this study we found that the SUMO-1/3-AA/-GS/-GN/-GA mutant can form sodium dodecyl sulfate (SDS)-dithiothreitol (DTT)-resistant complexes with cellular proteins, indicating that the GG motif is not strictly required for SUMOylation.