1 Department of Molecular Biology, Faculty of Science, Aarhus University, Aarhus University2 Department of Molecular Biology and Genetics - Gene Expression and Gene Medicine, Department of Molecular Biology and Genetics, Science and Technology, Aarhus University3 Department of Molecular Biology and Genetics - Gene Expression and Gene Medicine, Department of Molecular Biology and Genetics, Science and Technology, Aarhus University
In S. cerevisiae the RNA polymerase II-associated THO complex facilitates loading of the RNA-dependent ATPase Sub2p/UAP56 onto nascent transcripts. Mutation of individual THO components or Sub2p elicits dual transcription and mRNA nuclear export phenotypes. In addition Sub2p also has been implicated in pre-mRNA splicing, however, so far the precise function of THO/Sub2p remains unknown. Here we report a link between THO/Sub2p and mRNA 3’-end formation. In a search for mutant alleles affected at specific steps along the mRNA biogenic pathways of transcription, processing and nuclear export, we find that genetic interactions of the THO deletion mutant ∆mft1 strongly cluster with mRNA 3’-end processing mutants. High-resolution transcriptional run-on experiments corroborate this finding by showing that the transcription elongation defect observed in THO complex- and sub2-mutants occurs in very close proximity to cleavage/polyadenylation site sequences. Moreover, yeast extracts prepared from THO deletion- or sub2 mutant-strains are deficient for pre-mRNA 3’-end cleavage in an in vitro system uncoupled from transcription. The molecular basis for the link between THO/Sub2 and 3’ end processing will be discussed.