The N-terminal domain of Nup159 forms a beta-propeller that functions in mRNA export by tethering the helicase Dbp5 to the nuclear pore - PubMed (original) (raw)

The N-terminal domain of Nup159 forms a beta-propeller that functions in mRNA export by tethering the helicase Dbp5 to the nuclear pore

Christine S Weirich et al. Mol Cell. 2004.

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Abstract

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.

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