5t83
Structure of a guanidine-I riboswitch from S. acidophilusStructure of a guanidine-I riboswitch from S. acidophilus
Structural highlights
Publication Abstract from PubMedThe guanidine-I riboswitch is a conserved RNA element with approximately 2,000 known examples across four phyla of bacteria. It exists upstream of nitrogen metabolism and multidrug resistance transporter genes and alters expression through the specific recognition of a free guanidinium cation. Here we report the structure of a guanidine riboswitch aptamer from Sulfobacillus acidophilus at 2.7 A resolution. Helices P1, P1a, P1b, and P2 form a coaxial stack that acts as a scaffold for ligand binding. A previously unidentified P3 helix docks into P1a to form the guanidinium binding pocket, which is completely enclosed. Every functional group of the ligand is recognized through hydrogen bonding to guanine bases and phosphate oxygens. Guanidinium binding is further stabilized through cation-pi interactions with guanine bases. This allows the riboswitch to recognize guanidinium while excluding other bacterial metabolites with a guanidino group, including the amino acid arginine. Structural Basis for Ligand Binding to the Guanidine-I Riboswitch.,Reiss CW, Xiong Y, Strobel SA Structure. 2017 Jan 3;25(1):195-202. doi: 10.1016/j.str.2016.11.020. Epub 2016, Dec 22. PMID:28017522[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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