title: Interactions of Sen1, Nrd1, and Nab3 with multiple phosphorylated forms of the Rpb1 C-terminal domain in Saccharomyces cerevisiae.
abstract: The Saccharomyces cerevisiae SEN1 gene codes for a nuclear, ATP-dependent helicase which is embedded in a complex network of protein-protein interactions. Pleiotropic phenotypes of mutations in SEN1 suggest that Sen1 functions in many nuclear processes, including transcription termination, DNA repair, and RNA processing. Sen1, along with termination factors Nrd1 and Nab3, is required for the termination of noncoding RNA transcripts, but Sen1 is associated during transcription with coding and noncoding genes. Sen1 and Nrd1 both interact directly with Nab3, as well as with the C-terminal domain (CTD) of Rpb1, the largest subunit of RNA polymerase II. It has been proposed that Sen1, Nab3, and Nrd1 form a complex that associates with Rpb1 through an interaction between Nrd1 and the Ser5-phosphorylated (Ser5-P) CTD. To further study the relationship between the termination factors and Rpb1, we used two-hybrid analysis and immunoprecipitation to characterize sen1-R302W, a mutation that impairs an interaction between Sen1 and the Ser2-phosphorylated CTD. Chromatin immunoprecipitation indicates that the impairment of the interaction between Sen1 and Ser2-P causes the reduced occupancy of mutant Sen1 across the entire length of noncoding genes. For protein-coding genes, mutant Sen1 occupancy is reduced early and late in transcription but is similar to that of the wild type across most of the coding region. The combined data suggest a handoff model in which proteins differentially transfer from the Ser5- to the Ser2-phosphorylated CTD to promote the termination of noncoding transcripts or other cotranscriptional events for protein-coding genes.
authors.affiliation: Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Chinchilla
authors.forename: Juan B
authors.initials: JB
authors.lastname: Rodriguez-Molina
authors.forename: Doris
authors.initials: D
authors.lastname: Ursic
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Finkel
authors.forename: Aseem Z
authors.initials: AZ
authors.lastname: Ansari
authors.forename: Michael R
authors.initials: MR
authors.lastname: Culbertson
mesh_terms: D019943:Amino Acid Substitution; D004265:DNA Helicases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D046912:Multiprotein Complexes / Q000302:isolation & purification / Q000378:metabolism; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020365:RNA Helicases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D046912:Multiprotein Complexes; C090564:NAB3 protein, S cerevisiae; C082119:NGR1 protein, S cerevisiae; C491211:NRD1 protein, S cerevisiae; D009687:Nuclear Proteins; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C542347:SEN1 protein, S cerevisiae; D004265:DNA Helicases; D020365:RNA Helicases