title: Structure of the N-terminal Mlp1-binding domain of the Saccharomyces cerevisiae mRNA-binding protein, Nab2.
abstract: Nuclear abundant poly(A) RNA-binding protein 2 (Nab2) is an essential yeast heterogeneous nuclear ribonucleoprotein that modulates both mRNA nuclear export and poly(A) tail length. The N-terminal domain of Nab2 (residues 1-97) mediates interactions with both the C-terminal globular domain of the nuclear pore-associated protein, myosin-like protein 1 (Mlp1), and the mRNA export factor, Gfd1. The solution and crystal structures of the Nab2 N-terminal domain show a primarily helical fold that is analogous to the PWI fold found in several other RNA-binding proteins. In contrast to other PWI-containing proteins, we find no evidence that the Nab2 N-terminal domain binds to nucleic acids. Instead, this domain appears to mediate protein:protein interactions that facilitate the nuclear export of mRNA. The Nab2 N-terminal domain has a distinctive hydrophobic patch centered on Phe73, consistent with this region of the surface being a protein:protein interaction site. Engineered mutations within this hydrophobic patch attenuate the interaction with the Mlp1 C-terminal domain but do not alter the interaction with Gfd1, indicating that this patch forms a crucial component of the interface between Nab2 and Mlp1.
authors.affiliation: MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Grant
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Marshall
authors.forename: Ji-Chun
authors.initials: JC
authors.lastname: Yang
authors.forename: Milo B
authors.initials: MB
authors.lastname: Fasken
authors.forename: Seth M
authors.initials: SM
authors.lastname: Kelly
authors.forename: Michelle T
authors.initials: MT
authors.lastname: Harreman
authors.forename: David
authors.initials: D
authors.lastname: Neuhaus
authors.forename: Anita H
authors.initials: AH
authors.lastname: Corbett
authors.forename: Murray
authors.initials: M
authors.lastname: Stewart
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000737:chemistry*; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry*; D010649:Phenylalanine; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D012996:Solutions
chemical_list: C080988:MLP1 protein, S cerevisiae; C080773:NAB2 protein, S cerevisiae; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D012996:Solutions; D010649:Phenylalanine