Structural insights into recognition of c-di-AMP by the ydaO riboswitch.

ABSTRACT: Bacterial second messenger cyclic di-AMP (c-di-AMP) is implicated in signaling DNA damage and cell wall stress through interactions with several protein receptors and a widespread ydaO-type riboswitch. We report the crystal structures of c-di-AMP riboswitches from Thermoanaerobacter pseudethanolicus and Thermovirga lienii determined at ∼3.0-Å resolution. In both species, the RNA adopts an unforeseen 'square'-shaped pseudosymmetrical architecture that features two three-way junctions, a turn and a pseudoknot, positioned in the square corners. Uncharacteristically for riboswitches, the structure is stapled by two ligand molecules that span the interior of the structure and employ similar noncanonical interactions for RNA recognition. Mutations in either ligand-binding site negatively affect

SUBMITTER: Gao A 

PROVIDER: S-EPMC4294798 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature