S. Basu et al., A SPECIFIC MONOVALENT METAL-ION INTEGRAL TO THE AA PLATFORM OF THE RNA TETRALOOP RECEPTOR, Nature structural biology, 5(11), 1998, pp. 986-992
Metal ions are essential for the folding and activity of large catalyt
ic RNAs. While divalent metal ions have been directly implicated in RN
A tertiary structure formation, the role of monovalent ions has been l
argely unexplored. Here we report the first specific monovalent metal
ion binding site within a catalytic RNA. As seen crystallographically,
a potassium ion is coordinated immediately below AA platforms of the
Tetrahymena ribozyme P4-P6 domain, including that within the tetraloop
receptor. Interference and kinetic experiments demonstrate that potas
sium ion binding within the tetraloop receptor stabilizes the folding
of the P4-P6 domain and enhances the activity of the Azoarcus group I
intron. Since a monovalent ion binding site is integral to the tetralo
op receptor, a tertiary structural motif that occurs frequently in RNA
, monovalent metal ions are likely to participate in the folding and a
ctivity of a wide diversity of RNAs.