title: Structure and RNA interactions of the N-terminal RRM domains of PTB.
abstract: The polypyrimidine tract binding protein (PTB) is an important regulator of alternative splicing that also affects mRNA localization, stabilization, polyadenylation, and translation. NMR structural analysis of the N-terminal half of PTB (residues 55-301) shows a canonical structure for RRM1 but reveals novel extensions to the beta strands and C terminus of RRM2 that significantly modify the beta sheet RNA binding surface. Although PTB contains four RNA recognition motifs (RRMs), it is widely held that only RRMs 3 and 4 are involved in RNA binding and that RRM2 mediates homodimerization. However, we show here not only that the RRMs 1 and 2 contribute substantially to RNA binding but also that full-length PTB is monomeric, with an elongated structure determined by X-ray solution scattering that is consistent with a linear arrangement of the constituent RRMs. These new insights into the structure and RNA binding properties of PTB suggest revised models of its mechanism of action.
authors.affiliation: Department of Biological Sciences, Imperial College, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Simpson
authors.forename: Tom P
authors.initials: TP
authors.lastname: Monie
authors.forename: Andrea
authors.initials: A
authors.lastname: Szendröi
authors.forename: Natalia
authors.initials: N
authors.lastname: Davydova
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Tyzack
authors.forename: Maria R
authors.initials: MR
authors.lastname: Conte
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Read
authors.forename: Peter D
authors.initials: PD
authors.lastname: Cary
authors.forename: Dmitri I
authors.initials: DI
authors.lastname: Svergun
authors.forename: Peter V
authors.initials: PV
authors.lastname: Konarev
authors.forename: Stephen
authors.initials: S
authors.lastname: Curry
authors.forename: Stephen
authors.initials: S
authors.lastname: Matthews
mesh_terms: D000595:Amino Acid Sequence; D019281:Dimerization; D006801:Humans; D008958:Models, Molecular; D008970:Molecular Weight; D019906:Nuclear Magnetic Resonance, Biomolecular; D038941:Polypyrimidine Tract-Binding Protein / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D038941:Polypyrimidine Tract-Binding Protein; D012313:RNA