3bw1 | pdb_00003bw1
Crystal structure of homomeric yeast Lsm3 exhibiting novel octameric ring organisation
Structural highlights
FunctionLSM3_YEAST Component of LSm protein complexes, which are involved in RNA processing and may function in a chaperone-like manner. Component of the cytoplasmic LSM1-LSM7 complex which is thought to be involved in mRNA degradation by activating the decapping step. 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 snRNP, U4/U6.U5 snRNP, and free U6 snRNP). It binds directly to the U6 snRNA and plays a role in the biogenesis and stability of the U6 snRNP and U4/U6 snRNP complexes. It probably also is involved degradation of nuclear pre-mRNA by targeting them for decapping. LSM3 binds specifically to the 3'-terminal U-tract of U6 snRNA. LSM2-LSM8 probably is involved in processing of pre-tRNAs, pre-rRNAs and U3 snoRNA. LSM3, probably in a complex that contains LSM2-LSM7 but not LSM1 or LSM8, associates with the precursor of the RNA component of RNase P (pre-P RNA) and may be involved in maturing pre-P RNA. LSM3 is required for processing of pre-tRNAs, pre-rRNAs and U3 snoRNA.[1] [2] [3] [4] [5] [6] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSm and Sm-like (Lsm) proteins are core components of the ribonucleoprotein complexes essential to key nucleic acid processing events within the eukaryotic cell. They assemble as polyprotein ring scaffolds that have the capacity to bind RNA substrates and other necessary protein factors. The crystal structure of yeast Lsm3 reveals a new organisation of the L/Sm beta-propeller ring, containing eight protein subunits. Little distortion of the characteristic L/Sm fold is required to form the octamer, indicating that the eukaryotic Lsm ring may be more pliable than previously thought. The homomeric Lsm3 octamer is found to successfully recruit Lsm6, Lsm2 and Lsm5 directly from yeast lysate. Our crystal structure shows the C-terminal tail of each Lsm3 subunit to be engaged in connections across rings through specific beta-sheet interactions with elongated loops protruding from neighbouring octamers. While these loops are of distinct length for each Lsm protein and generally comprise low-complexity polar sequences, several Lsm C-termini comprise hydrophobic sequences suitable for beta-sheet interactions. The Lsm3 structure thus provides evidence for protein-protein interactions likely utilised by the highly variable Lsm loops and termini in the recruitment of RNA processing factors to mixed Lsm ring scaffolds. Our coordinates also provide updated homology models for the active Lsm[1-7] and Lsm[2-8] heptameric rings. Crystal structure of Lsm3 octamer from Saccharomyces cerevisiae: implications for Lsm ring organisation and recruitment.,Naidoo N, Harrop SJ, Sobti M, Haynes PA, Szymczyna BR, Williamson JR, Curmi PM, Mabbutt BC J Mol Biol. 2008 Apr 11;377(5):1357-71. Epub 2008 Jan 11. PMID:18329667[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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