A novel role for Sem1 and TREX-2 in transcription involves their impact on recruitment and H2B deubiquitylation activity of SAGA

Nucleic Acids Res. 2013 Jun;41(11):5655-68. doi: 10.1093/nar/gkt272. Epub 2013 Apr 17.


Transcription and mRNA export are linked processes. However, the molecular mechanisms of this coordination are not clear. Sus1 (hENY2) participates in this coordination as part of two protein complexes: SAGA, a transcriptional co-activator; TREX-2, which functions in mRNA biogenesis and export. Here, we investigate the coordinated action of SAGA and TREX-2 required for gene expression. We demonstrate that TREX-2 subunit Sem1 also participates in transcription activation. Like Sus1, Sem1 is required for the induction of ARG1 and GAL1, these being SAGA-regulated genes. Chromatin immunoprecipitations show that proper recruitment of certain SAGA subunits to the GAL1 promoter depends on Sem1. Notably, both in vivo and in vitro analyses reveal that Sem1 influences SAGA-dependent histone H2B deubiquitylation. Most of these phenotypes are also found to depend on another TREX-2 subunit, Thp1. These results unveil a new role for Sem1 in the activation of the SAGA-dependent gene GAL1 and influencing H2B deubiquitylation. Our work provides insights into a novel functional relationship between Sem1 and the SAGA complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arginase / biosynthesis
  • Arginase / genetics
  • Galactokinase / biosynthesis
  • Galactokinase / genetics
  • Gene Expression Regulation, Fungal*
  • Histones / metabolism*
  • Nuclear Proteins / metabolism
  • Promoter Regions, Genetic
  • Proteasome Endopeptidase Complex / metabolism*
  • Proteasome Endopeptidase Complex / physiology
  • Protein Subunits / metabolism
  • Protein Subunits / physiology
  • RNA-Binding Proteins / metabolism
  • Ribonucleoproteins / genetics
  • Saccharomyces cerevisiae Proteins / biosynthesis
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology
  • Trans-Activators / metabolism*
  • Transcriptional Activation*
  • Ubiquitination


  • Histones
  • Nuclear Proteins
  • Protein Subunits
  • RNA-Binding Proteins
  • Ribonucleoproteins
  • SAGA complex, S cerevisiae
  • SEM1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Sus1 protein, S cerevisiae
  • Thp1 protein, S cerevisiae
  • Trans-Activators
  • GAL1 protein, S cerevisiae
  • Galactokinase
  • Proteasome Endopeptidase Complex
  • ARG1 protein, S cerevisiae
  • Arginase