title: Structural Characterization of the Chaetomium thermophilum TREX-2 Complex and its Interaction with the mRNA Nuclear Export Factor Mex67:Mtr2.
abstract: The TREX-2 complex integrates mRNA nuclear export into the gene expression pathway and is based on a Sac3 scaffold to which Thp1, Sem1, Sus1, and Cdc31 bind. TREX-2 also binds the mRNA nuclear export factor, Mex67:Mtr2, through the Sac3 N-terminal region (Sac3N). Here, we characterize Chaetomium thermophilum TREX-2, show that the in vitro reconstituted complex has an annular structure, and define the structural basis for interactions between Sac3, Sus1, Cdc31, and Mex67:Mtr2. Crystal structures show that the binding of C. thermophilum Sac3N to the Mex67 NTF2-like domain (Mex67(NTF2L)) is mediated primarily through phenylalanine residues present in a series of repeating sequence motifs that resemble those seen in many nucleoporins, and Mlp1 also binds Mex67:Mtr2 using a similar motif. Deletion of Sac3N generated growth and mRNA export defects in Saccharomyces cerevisiae, and we propose TREX-2 and Mlp1 function to facilitate export by concentrating mature messenger ribonucleoparticles at the nuclear pore entrance.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK; Biochemie-Zentrum der Universität Heidelberg, INF328, 69120 Heidelberg, Germany.
authors.forename: Lyudmila
authors.initials: L
authors.lastname: Dimitrova
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
authors.forename: Eugene
authors.initials: E
authors.lastname: Valkov
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Aibara
authors.affiliation: Biochemie-Zentrum der Universität Heidelberg, INF328, 69120 Heidelberg, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Flemming
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: McLaughlin
authors.affiliation: Biochemie-Zentrum der Universität Heidelberg, INF328, 69120 Heidelberg, Germany. Electronic address: ed.hurt@bzh.uni-heidelberg.de.
authors.forename: Ed
authors.initials: E
authors.lastname: Hurt
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK. Electronic address: ms@mrc-lmb.cam.ac.uk.
authors.forename: Murray
authors.initials: M
authors.lastname: Stewart
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D002597:Chaetomium; D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000737:chemistry* / Q000648:ultrastructure; D008958:Models, Molecular; D008969:Molecular Sequence Data; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry* / Q000648:ultrastructure; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D034443:RNA Transport; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000648:ultrastructure; D017386:Sequence Homology, Amino Acid
chemical_list: D005656:Fungal Proteins; D029543:Nucleocytoplasmic Transport Proteins; D016601:RNA-Binding Proteins