3swn

Structure of the LSm657 Complex: An Assembly Intermediate of the LSm1 7 and LSm2 8 Rings

spinqualitylabelsall models 3swn, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3swn is a 12 chain structure with sequence from Fission yeast. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ZN Gene: lsm7, SPCC285.12 (Fission yeast), lsm5, SPBC20F10.09 (Fission yeast), lsm6, SPAC2F3.17c (Fission yeast) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [LSM7_SCHPO] Component of LSm protein complexes, which are involved in RNA processing and may function in a chaperone-like manner. Probable component of the spliceosome. [LSM6_SCHPO] Component of LSm protein complexes, which are involved in RNA processing and may function in a chaperone-like manner, facilitating the efficient association of RNA processing factors with their substrates. Component of the cytoplasmic LSM1-LSM7 complex, which is thought to be involved in mRNA degradation by activating the decapping step in the 5'-to-3' mRNA decay pathway. Component of the nuclear LSM2-LSM8 complex, which is involved in splicing of nuclear mRNAs. LSM2-LSM8 associates with multiple snRNP complexes containing the U6 snRNA (U4/U6 di-snRNP, spliceosomal U4/U6.U5 tri-snRNP, and free U6 snRNP). It binds directly to the 3'-terminal U-tract of U6 snRNA and plays a role in the biogenesis and stability of the U6 snRNP and U4/U6 snRNP complexes. LSM2-LSM8 probably also is involved degradation of nuclear pre-mRNA by targeting them for decapping, and in processing of pre-tRNAs, pre-rRNAs and U3 snoRNA (By similarity). [LSM5_SCHPO] Component of LSm protein complexes, which are involved in RNA processing and may function in a chaperone-like manner. LSm5 is required for processing of pre-tRNAs, pre-rRNAs and U3 snoRNA (By similarity). Publication Abstract from PubMed The nuclear LSm2-8 (like Sm) complex and the cytoplasmic LSm1-7 complex play a central role in mRNA splicing and degradation, respectively. The LSm proteins are related to the spliceosomal Sm proteins that form a heteroheptameric ring around small nuclear RNA. The assembly process of the heptameric Sm complex is well established and involves several smaller Sm assembly intermediates. The assembly of the LSm complex, however, is less well studied. Here, we solved the 2.5 A-resolution structure of the LSm assembly intermediate that contains LSm5, LSm6, and LSm7. The three monomers display the canonical Sm fold and arrange into a hexameric LSm657-657 ring. We show that the order of the LSm proteins within the ring is consistent with the order of the related SmE, SmF, and SmG proteins in the heptameric Sm ring. Nonetheless, differences in RNA binding pockets prevent the prediction of the nucleotide binding preferences of the LSm complexes. Using high-resolution NMR spectroscopy, we confirm that LSm5, LSm6, and LSm7 also assemble into a 60-kDa hexameric ring in solution. With a combination of pull-down and NMR experiments, we show that the LSm657 complex can incorporate LSm23 in order to assemble further towards native LSm rings. Interestingly, we find that the NMR spectra of the LSm57, LSm657-657, and LSm23-657 complexes differ significantly, suggesting that the angles between the LSm building blocks change depending on the ring size of the complex. In summary, our results identify LSm657 as a plastic and functional building block on the assembly route towards the LSm1-7 and LSm2-8 complexes. Structure of the LSm657 complex: an assembly intermediate of the LSm1-7 and LSm2-8 rings.,Mund M, Neu A, Ullmann J, Neu U, Sprangers R J Mol Biol. 2011 Nov 25;414(2):165-76. Epub 2011 Oct 6. PMID:22001694 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Sm-like protein

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