Polypeptide GalNAc-T2 interacts with RNA polymerase II and enhances transcriptional activity

ZLOCOWSKI N; CEJAS, RB; BOCCO, JL; IRAZOQUI FJ

Mendoza

Congreso; Sociedad Argentina de Investigaciones Bioquímicas (SAIB); 2012

The RNA polymerase II (Pol II) transcription machinery is responsible for the transcription of thousands of protein-encoding genes in eukaryotic cells. The structure and regulation of the Pol II machinery are critical for transcription, and participation of general transcription factors is required. In view of the binding ability of the lectin domain of polypeptide GalNAc-transferases (ppGalNAc-Ts), we studied the interaction of ppGalNAc-T2 with Pol II, the effect of acetylation of ppGalNAc-T2 on such interaction, and the role of the lectin domain of ppGalNAc-T2 in transcriptional activity. Non-acetylated ppGalNAc-T2 bound to the C-terminal domain (CTD) and glycosylated CTD of Pol II. ppGalNAc-T2 interaction with Pol II is abolished by acetylation of ppGalNAc-T2. The K521Q mutation, which mimicked acetylation of the lectin domain, had a similar effect on Pol II binding. In vivo assays also revealed the interaction of ppGalNAc-T2 with Pol II. Reporter gene assays reported a correlation between high ppGalNAc-T2 expression levels and enhanced transcriptional activity while K521Q mutation eliminated the transcriptional activation. These findings clearly demonstrate the important role of the lectin domain of ppGalNAc-T2 in the regulation of transcriptional activity. ppGalNAc-Ts in general may play key roles in transcriptional activity as activators that can be modulated by acetylation.