Biochemical methods open tracks to understand how transcription factors modulate RNA polymerase II activity. It is now well established that post-translational modifications play a critical role in modulating transcription efficiency. We focus on RNA polymerase II. The coupling between transcription and post-transcriptional events rely upon phosphorylation of multiple heptapeptide repeats in the carboxyl-terminal domain (CTD) of RNA polymerase II largest subunit. Several protein kinases such as the CDK9 subunit of P-TEFb (the Positive Transcription Factor) and phosphatases have been identified as CTD kinases or CTD phosphatases.

PNG - 133.8 ko
A phosphorylation/dephosphorylation cycle controls transcription and RNA maturation

As an example, phosphorylation of the CTD is well established to be a major rate-limiting step for immunodeficiency virus (HIV) transcription. Recruitment of P-TEFb is critical and involves association of its Cyclin T1 subunit with the viral protein Tat and the TAR structure at the 5’end of the viral transcript. These findings indicated that RNA protein interactions also contributed to regulate RNA polymerase activity.

PNG - 67.7 ko

Dernière mise à jour : 14 septembre 2007