The N-terminal domain of Nup159 forms a beta-propeller that functions in mRNA export by tethering the helicase Dbp5 to the nuclear pore.
Nuclear export of mRNA in eukaryotic cells is mediated by soluble transport factors and components of the nuclear pore complex (NPC). The cytoplasmically oriented nuclear pore protein Nup159 plays a critical role in mRNA export through its conserved N-terminal domain (NTD). Here, we report the crystal structure of the Nup159 NTD, refined to 2.5 A. The structure reveals an unusually asymmetric seven-bladed beta-propeller that is structurally conserved throughout eukarya. Using structure-based conservation analysis, we have targeted specific surface residues for mutagenesis. Residue substitutions in a conserved loop of the NTD abolish in vitro binding to Dbp5, a DEAD box helicase required for mRNA export. In vivo, these mutations cause Dbp5 mislocalization and block mRNA export. These findings suggest that the Nup159 NTD functions in mRNA export as a binding platform, tethering shuttling Dbp5 molecules at the nuclear periphery and locally concentrating this mRNA remodeling factor at the cytoplasmic face of the NPC.
Weirich
Christine S
CS
Division of Cell and Developmental Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA.
Erzberger
Jan P
JP
Berger
James M
JM
Weis
Karsten
K
D000251:Adenosine Triphosphatases / Q000737:chemistry; D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism; D002850:Chromatography, Gel; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D017403:In Situ Hybridization; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D022022:Nuclear Pore / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020365:RNA Helicases / Q000737:chemistry* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*
C093510:NUP159 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; C492382:DBP5 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases