title: Solution structure of the U2 snRNP protein Rds3p reveals a knotted zinc-finger motif.
abstract: Rds3p, a component of the U2 snRNP subcomplex SF3b, is essential for pre-mRNA splicing and is extremely well conserved in all eukaryotic species. We report here the solution structure of Rds3p, which reveals an unusual knotted fold unrelated to previously known knotted proteins. Rds3p has a triangular shape with a GATA-like zinc finger at each vertex. Pairs of cysteines contributing to each finger are arranged nonsequentially in a permuted arrangement reminiscent of domain-swapping but which here involves segments of subdomains within a single chain. We suggest that the structure arose through a process of segment swapping after gene duplication. The fingers are connected through beta-strands and loops, forming an overall topology strongly resembling a "triquetra knot." The conservation and surface properties of Rds3p suggest that it functions as a platform for protein assembly within the multiprotein SF3b complex of U2 snRNP. The recombinant protein used for structure determination is biologically active, as it restores splicing activity in a yeast splicing extract depleted of native Rds3p.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, United Kingdom.
authors.forename: Anne-Marie M
authors.initials: AM
authors.lastname: van Roon
authors.forename: Nikolaus M
authors.initials: NM
authors.lastname: Loening
authors.forename: Eiji
authors.initials: E
authors.lastname: Obayashi
authors.forename: Ji-Chun
authors.initials: JC
authors.lastname: Yang
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Newman
authors.forename: Helena
authors.initials: H
authors.lastname: Hernández
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Nagai
authors.forename: David
authors.initials: D
authors.lastname: Neuhaus
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry; D011487:Protein Conformation; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D012996:Solutions; D016335:Zinc Fingers
chemical_list: D002352:Carrier Proteins; C478922:RDS3 protein, S cerevisiae; D017413:Ribonucleoprotein, U2 Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; D012996:Solutions; D003545:Cysteine