[Molecular mechanisms of coupling processes of transcription termination and polyadenylation of pro-mRNA]

The recent literature data devoted to coordination of the processes of the transcription termination and polyadenylation have been analyzed. The model of coupling of these processes synthesizing the available conceptions is proposed. The effective transcription termination occurs under simultaneous interactions of RNA polymerase (Pol II) both with the signal element of DNA (terminator or enhancer) and the transcript polyadenylation site. The unique C-terminal domain (CTD) of the largest enzyme subunit contacts pre-mRNA. The cleavage factors are associated with this domain. Pol II is an essential cofactor in the cleavage reaction. The mechanism of this reaction influence on the termination transcription is unknown but the cleavage is accompanied by degradation of the 3' end part of the transcript. The RNA release from Pol II induces destabilization of the contact between the enzyme and the DNA duplex immediately after the transcription bubble, which promotes release Pol II from the template.