6ck4

G96A mutant of the PRPP riboswitch from T. mathranii bound to ppGpp

spinqualitylabelsall models 6ck4, resolution 3.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6ck4 is a 4 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: G4P, GTP, K, MG, MPD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Two classes of riboswitches related to the ykkC guanidine-I riboswitch bind phosphoribosyl pyrophosphate (PRPP) and guanosine tetraphosphate (ppGpp). Here we report the co-crystal structure of the PRPP aptamer and its ligand. We also report the structure of the G96A point mutant that prefers ppGpp over PRPP with a dramatic 40,000-fold switch in specificity. The ends of the aptamer form a helix that is not present in the guanidine aptamer and is involved in the expression platform. In the mutant, the base of ppGpp replaces G96 in three-dimensional space. This disrupts the S-turn, which is a primary structural feature of the ykkC RNA motif. These dramatic differences in ligand specificity are achieved with minimal mutations. ykkC aptamers are therefore a prime example of an RNA fold with a rugged fitness landscape. The ease with which the ykkC aptamer acquires new specificity represents a striking case of evolvability in RNA. Structures of two aptamers with differing ligand specificity reveal ruggedness in the functional landscape of RNA.,Knappenberger AJ, Reiss CW, Strobel SA Elife. 2018 Jun 7;7. pii: 36381. doi: 10.7554/eLife.36381. PMID:29877798 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Riboswitch 3D structures

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