Klockner C, et al. (2009) Mutational Uncoupling of the Role of Sus1 in Nuclear Pore Complex Targeting of an mRNA Export Complex and Histone H2B Deubiquitination. J Biol Chem 284(18):12049-56
Abstract: Sus1 is an evolutionary conserved protein that functions both in transcription and mRNA export and has been proposed to contribute to coupling these processes in yeast. Sus1 mediates its different roles as a component of both the histone H2B deubiquitinating module (Sus1-Sgf11-Ubp8-Sgf73) of the SAGA transcriptional co-activator, and the mRNA export complex, TREX-2 (Sus1-Sac3-Thp1-Cdc31). We have dissected the different functions of Sus1 with respect to its partitioning in transcription and export complexes using a mutational approach. Here we show that the sus1-10 (E18>A, G20>A) and sus1-12 (V73>A, D75>A) alleles of Sus1 can be dissociated from TREX-2 while leaving its interaction with SAGA largely intact. Conversely, the binding to both TREX-2 and SAGA was impaired in the sus1-11 allele (G37>A, W38>A), in which two highly conserved residues were mutated. In vitro experiments demonstrated that dissociation of mutant Sus1 from its partners is caused by a reduced affinity towards the TREX-2 subunit, Sac3, and the SAGA factor, Sgf11, respectively. Consistent with the biochemical data, these sus1 mutant alleles showed differential genetic relationships with SAGA and mRNA export mutants. In vivo, all three sus1 mutants were impaired in targeting TREX-2 (i.e. Sac3) to the NPCs and exhibited nuclear mRNA export defects. This study has implications for how Sus1, in combination with distinct interaction partners, can regulate diverse aspects of gene expression.
|Status: Published||Type: Journal Article||PubMed ID: 19269973|
Topics addressed in this paper
Number of different genes curated to this paper: 13
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|Topics||Genes (#1 - 10 )|
|Fungal Related Genes/Proteins|
|Non-Fungal Related Genes/Proteins|
|Protein Physical Properties|
|Protein Sequence Features|
|Topics||Genes (#11 - 13 )|