biostudies-literatureKnappenberger AJU.S. Department of Health and Human ServicesNIGMS NIH HHS1361-1366https://www.ebi.ac.uk/biostudies/studies/S-EPMC7311191biostudies-literatureUnknown59(13)The modularity of protein domains is well-known, but the existence of independent domains that confer function in RNA is less established. Recently, a family of RNA aptamers termed <i>ykkC</i> was discovered; they bind at least four ligands of very different chemical composition, including guanidine, phosphoribosyl pyrophosphate (PRPP), and guanosine tetraphosphate (ppGpp) (graphical abstract). Structures of these aptamers revealed an architecture characterized by two coaxial helical stacks. The first helix appears to be a generic scaffold, while the second helix forms the most contacts to the ligands. To determine if these two regions within the aptamer are modular units for ligand recognition, we swapped the ligand-binding coaxial stacks of a guanidine aptamer and a PRPP aptamer. This opBiochemistryA Modular RNA Domain That Confers Differential Ligand Specificity.PMC7311191P01 GM022778GM022778T32 GM100884Focht CMStrobel SAReiss CWKnappenberger AJfalseA Modular RNA Domain That Confers Differential Ligand Specificity.The modularity of protein domains is well-known, but the existence of independent domains that confer function in RNA is less established. Recently, a family of RNA aptamers termed <i>ykkC</i> was discovered; they bind at least four ligands of very different chemical composition, including guanidine, phosphoribosyl pyrophosphate (PRPP), and guanosine tetraphosphate (ppGpp) (graphical abstract). Structures of these aptamers revealed an architecture characterized by two coaxial helical stacks. The first helix appears to be a generic scaffold, while the second helix forms the most contacts to the ligands. To determine if these two regions within the aptamer are modular units for ligand recognition, we swapped the ligand-binding coaxial stacks of a guanidine aptamer and a PRPP aptamer. This op2020-01-01T00:00:00Z2020 Apr2026-04-29T00:17:24.53Z2022-02-09T12:46:07.826ZS-EPMC73111913220241610.1021/acs.biochem.0c00117