Plasticity of the RNA kink turn structural motif.
The kink turn (K-turn) is an RNA structural motif found in many biologically significant RNAs. While most examples of the K-turn have a similar fold, the crystal structure of the Azoarcus group I intron revealed a novel RNA conformation, a reverse kink turn bent in the direction opposite that of a consensus K-turn. The reverse K-turn is bent toward the major grooves rather than the minor grooves of the flanking helices, yet the sequence differs from the K-turn consensus by only a single nucleotide. Here we demonstrate that the reverse bend direction is not solely defined by internal sequence elements, but is instead affected by structural elements external to the K-turn. It bends toward the major groove under the direction of a tetraloop-tetraloop receptor. The ability of one sequence to form two distinct structures demonstrates the inherent plasticity of the K-turn sequence. Such plasticity suggests that the K-turn is not a primary element in RNA folding, but instead is shaped by other structural elements within the RNA or ribonucleoprotein assembly.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.
Alexandra H
AH
Antonioli
Jesse C
JC
Cochrane
Sarah V
SV
Lipchock
Scott A
SA
Strobel
D020627:Azoarcus / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D018360:Crystallography, X-Ray; D007438:Introns; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry*; D012329:RNA, Bacterial / Q000737:chemistry*
D012329:RNA, Bacterial; D012313:RNA