5gvq
Solution structure of the first RRM domain of human spliceosomal protein SF3b49
Structural highlights
DiseaseSF3B4_HUMAN Defects in SF3B4 are the cause of acrofacial dysostosis type 1 (AFD1) [MIM:154400. AFD1 is a form of acrofacial dysostosis, a group of disorders which are characterized by malformation of the craniofacial skeleton and the limbs. The major facial features of AFD1 include downslanted palpebral fissures, midface retrusion, and micrognathia, the latter of which often requires the placement of a tracheostomy in early childhood. Limb defects typically involve the anterior (radial) elements of the upper limbs and manifest as small or absent thumbs, triphalangeal thumbs, radial hyoplasia or aplasia, and radioulnar synostosis. Phocomelia of the upper limbs and, occasionally, lower-limb defects have also been reported.[1] FunctionSF3B4_HUMAN Subunit of the splicing factor SF3B required for 'A' complex assembly formed by the stable binding of U2 snRNP to the branchpoint sequence (BPS) in pre-mRNA. Sequence independent binding of SF3A/SF3B complex upstream of the branch site is essential, it may anchor U2 snRNP to the pre-mRNA. May also be involved in the assembly of the 'E' complex. SF3B4 has been found in complex 'B' and 'C' as well. Belongs also to the minor U12-dependent spliceosome, which is involved in the splicing of rare class of nuclear pre-mRNA intron. Publication Abstract from PubMedThe spliceosomal protein SF3b49, a component of the splicing factor 3b (SF3b) protein complex in the U2 small nuclear ribonucleoprotein, contains two RNA recognition motif (RRM) domains. In yeast, the first RRM domain (RRM1) of Hsh49 protein (yeast orthologue of human SF3b49) reportedly interacts with another component, Cus1 protein (orthologue of human SF3b145). Here, we solved the solution structure of the RRM1 of human SF3b49 and examined its mode of interaction with a fragment of human SF3b145 using NMR methods. Chemical shift mapping showed that the SF3b145 fragment spanning residues 598-631 interacts with SF3b49 RRM1, which adopts a canonical RRM fold with a topology of beta1-alpha1-beta2-beta3-alpha2-beta4. Furthermore, a docking model based on NOESY measurements suggests that residues 607-616 of the SF3b145 fragment adopt a helical structure that binds to RRM1 predominantly via alpha1, consequently exhibiting a helix-helix interaction in almost antiparallel. This mode of interaction was confirmed by a mutational analysis using GST pull-down assays. Comparison with structures of all RRM domains when complexed with a peptide found that this helix-helix interaction is unique to SF3b49 RRM1. Additionally, all amino acid residues involved in the interaction are well conserved among eukaryotes, suggesting evolutionary conservation of this interaction mode between SF3b49 RRM1 and SF3b145. Solution structure of the first RNA recognition motif domain of human spliceosomal protein SF3b49 and its mode of interaction with a SF3b145 fragment.,Kuwasako K, Nameki N, Tsuda K, Takahashi M, Sato A, Tochio N, Inoue M, Terada T, Kigawa T, Kobayashi N, Shirouzu M, Ito T, Sakamoto T, Wakamatsu K, Guntert P, Takahashi S, Yokoyama S, Muto Y Protein Sci. 2017 Feb;26(2):280-291. doi: 10.1002/pro.3080. Epub 2016 Nov 27. PMID:27862552[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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