3k0j | pdb_00003k0j

Crystal structure of the E. coli ThiM riboswitch in complex with thiamine pyrophosphate and the U1A crystallization module

spinqualitylabelsall models 3k0j, resolution 3.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3k0j is a 6 chain structure with sequence from Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: MG, TPP Gene: SNRPA, U1A protein (HUMAN) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [SNRPA_HUMAN] Binds stem loop II of U1 snRNA. It is the first snRNP to interact with pre-mRNA. This interaction is required for the subsequent binding of U2 snRNP and the U4/U6/U5 tri-snRNP. In a snRNP-free form (SF-A) may be involved in coupled pre-mRNA splicing and polyadenylation process. Binds preferentially to the 5'-UGCAC-3' motif in vitro. 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 PubMed The thi-box riboswitch regulates gene expression in response to the intracellular concentration of thiamine pyrophosphate (TPP) in archaea, bacteria, and eukarya. To complement previous biochemical, genetic, and structural studies of this phylogenetically widespread RNA domain, we have characterized its interaction with TPP by isothermal titration calorimetry. This shows that TPP binding is highly dependent on Mg(2+) concentration. The dissociation constant decreases from approximately 200 nM at 0.5 mM Mg(2+) concentration to approximately 9 nM at 2.5 mM Mg(2+) concentration. Binding is enthalpically driven, but the unfavorable entropy of binding decreases as Mg(2+) concentration rises, suggesting that divalent cations serve to pre-organize the RNA. Mutagenesis, biochemical analysis, and a new crystal structure of the riboswitch suggest that a critical element that participates in organizing the riboswitch structure is the tertiary interaction formed between the P3 and L5 regions. This tertiary contact is distant from the TPP binding site, but calorimetric analysis reveals that even subtle mutations in L5 can have readily detectable effects on TPP binding. The thermodynamic signatures of these mutations, namely decreased favorable enthalpy of binding and small effects on entropy of binding, are consistent with the P3-L5 association contributing allosterically to TPP-induced compaction of the RNA. Thermodynamic analysis of ligand binding and ligand binding-induced tertiary structure formation by the thiamine pyrophosphate riboswitch.,Kulshina N, Edwards TE, Ferre-D'Amare AR RNA. 2010 Jan;16(1):186-96. Epub 2009 Nov 30. PMID:19948769 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Nucleoprotein 3D structures

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