The kink-turn is a widespread motif in RNA consisting of a three-nucleotide bulge flanked on one side by consecutive A3G mismatches. Important examples are found in the ribosome, U4 RNA, and in snoRNAs involved in RNA modification. The motif is a common protein binding site, and the RNA has been found to adopt a tightly kinked conformation in crystal structures. However, in free solution there is a dynamic exchange between kinked and extended conformations, with the equilibrium driven toward the kinked form by the addition of metal ions. Here we used fluorescence resonance energy transfer (FRET) to show that the L7Ae protein of Archaeoglobus fulgidus binds to RNA containing a kink-turn with nanomolar affinity, and induces folding into the tightly kinked conformation even in the absence of metal ions. Thus this RNA may act as a relatively flexible hinge during RNA folding, until fixed into its ultimate kinked structure by the binding of L7 or related protein.

Archaeal Proteins↗

PubMed2002

Postischemic microcirculatory blood flow correlates negatively and independently with plasma C-reactive protein in longstanding type 1 diabetes.

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Blood Flow Velocity↗