Unraveling the mechanistic features of RNA polymerase II termination by the 5'-3' exoribonuclease Rat1.

Within a complex with Rai1, the 5'-3' exoribonuclease Rat1 promotes termination of RNA polymerase II (RNAPII) on protein-coding genes, but its underlying molecular mechanism is still poorly understood. Using in vitro transcription termination assays, we have found that RNAPII is prone to more effective termination by Rat1/Rai1 when its catalytic ...
site is disrupted due to NTP misincorporation, implying that paused RNAPII, which is often found in vivo near termination sites, could adopt a similar configuration to Rat1/Rai1 and trigger termination. Intriguingly, yeast Rat1/Rai1 does not terminate Escherichia coli RNAP, implying that a specific interaction between Rat1/Rai1 and RNAPII may be required for termination. Furthermore, the efficiency of termination increases as the RNA transcript undergoing degradation by Rat1 gets longer, which suggests that Rat1 may generate a driving force for dissociating RNAPII from the template while degrading the nascent transcripts to catch up to the polymerase. These results indicate that multiple mechanistic features contribute to Rat1-mediated termination of RNAPII.
Mesh Terms:
Adenosine Triphosphate, Base Sequence, Exoribonucleases, Models, Genetic, Molecular Sequence Data, Mutation, Nuclear Proteins, RNA Polymerase II, RNA, Fungal, Saccharomyces cerevisiae Proteins, Transcription Factors, Transcription Termination, Genetic
Nucleic Acids Res.
Date: Mar. 11, 2015
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