title: Identification of novel Saccharomyces cerevisiae proteins with nuclear export activity: cell cycle-regulated transcription factor ace2p shows cell cycle-independent nucleocytoplasmic shuttling.
abstract: Nuclear export of proteins containing leucine-rich nuclear export signals (NESs) is mediated by the NES receptor CRM1/Crm1p. We have carried out a yeast two-hybrid screen with Crm1p as a bait. The Crm1p-interacting clones were subscreened for nuclear export activity in a visual assay utilizing the Crm1p-inhibitor leptomycin B (LMB). This approach identified three Saccharomyces cerevisiae proteins not previously known to have nuclear export activity. These proteins are the 5' RNA triphosphatase Ctl1p, the cell cycle-regulated transcription factor Ace2p, and a protein encoded by the previously uncharacterized open reading frame YDR499W. Mutagenesis analysis show that YDR499Wp contains an NES that conforms to the consensus sequence for leucine-rich NESs. Mutagenesis of Ctl1p and Ace2p were unable to identify specific NES residues. However, a 29-amino-acid region of Ace2p, rich in hydrophobic residues, contains nuclear export activity. Ace2p accumulates in the nucleus at the end of mitosis and activates early-G(1)-specific genes. We now provide evidence that Ace2p is nuclear not only in late M-early G(1) but also during other stages of the cell cycle. This feature of Ace2p localization explains its ability to activate genes such as CUP1, which are not expressed in a cell cycle-dependent manner.
authors.affiliation: Howard Hughes Medical Institute, Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA.
authors.forename: T H
authors.initials: TH
authors.lastname: Jensen
authors.forename: M
authors.initials: M
authors.lastname: Neville
authors.forename: J C
authors.initials: JC
authors.lastname: Rain
authors.forename: T
authors.initials: T
authors.lastname: McCarthy
authors.forename: P
authors.initials: P
authors.lastname: Legrain
authors.forename: M
authors.initials: M
authors.lastname: Rosbash
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D016193:G1 Phase; D005982:Glutathione Transferase / Q000378:metabolism; D026901:Membrane Transport Proteins; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016366:Open Reading Frames; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: C066778:ACE2 protein, S cerevisiae; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D005231:Fatty Acids, Unsaturated; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C065637:choline transporter; D005982:Glutathione Transferase; C038753:leptomycin B