The objective of the proposed studies is to understand how a set of RNA-binding proteins regulate eucaryotic transcription elongation and termination. Our recent studies indicate that specific RNA sequence elements can direct RNA polymerase II termination in a manner that does not lead to polyadenylation of the nascent transcript. In Saccharomyces cerevisiae this mechanism is used to produce 3-ends on non-polyadenylated small nuclear and small nucleolar RNAs (snRNAs and snoRNAs). In addition, we have shown that several mRNAs are regulated by a similar mechanism. This regulatory pathway requires the function of two RNA-binding proteins, Nrd1 and Nab3, and operates through recognition of specific cis-elements in the nascent transcript. This pathway also requires the Seni RNA helicase and both the pol II CTD and a CTD kinase. The immediate objective of the proposed studies is to understand precisely how Nrd1 and Nab3 function to cause transcription termination while the longer term objective is to understand the role of the CTD and SCAFs in regulating transcription by RNA polymerase II.In this proposal our specific aims are to: (1) Define cis-elements that regulate transcription elongation through the Nrd1 -Nab3 pathway; (2) Further dissect the genetic interactions among components of the Nrd1 pathway; (3) Develop a Nrd1p-Nab3p-dependent in vitro termination assay; and (4) Characterize mammalian Nrd1-Iike proteins (SCAFs) and determine whether they play a similar role in regulating transcription termination.The ability of sequences in the nascent pol II transcript to trigger termination of non-polyadenylated transcripts is a novel regulatory mechanism. This pathway is similar to the mechanism that regulates elongation of transcripts from the HIV LTR. Similar to HIV regulation, the Nrd1-Nab3 mechanism requires the pol II CTD and a CTD kinase. Further understanding of this pathway will be important in understanding how eucaryotic genes are regulated and how these pathways may be modulated for therapeutic reasons
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