The structural basis of myotonic dystrophy from the crystal structure of CUG repeats.
Myotonic dystrophy (DM) type 1 is associated with an expansion of (>50) CTG repeats within the 3' untranslated region (UTR) of the dystrophin myotonin protein kinase gene (dmpk). In the corresponding mRNA transcript, the CUG repeats form an extended stem-loop structure. The double-stranded RNA of the stem sequesters RNA binding proteins away from their normal cellular targets resulting in aberrant transcription, alternative splicing patterns, or both, thereby leading to DM. To better understand the structural basis of DM type 1, we determined to 1.58-A resolution the x-ray crystal structure of an 18-bp RNA containing six CUG repeats. The CUG repeats form antiparallel double-stranded helices that stack end-on-end in the crystal to form infinite, pseudocontinuous helices similar to the long CUG stem loops formed by the expanded CUG repeats in DM type 1. The CUG helix is very similar in structure to A-form RNA with the exception of the unique U-U mismatches. This structure provides a high-resolution view of a toxic, trinucleotide repeat RNA.
Mooers
Blaine H M
BH
Department of Chemistry, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403-1229, USA.
Logue
Jeremy S
JS
Berglund
J Andrew
JA
D020413:3' Untranslated Regions; D003461:Crystallography; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009223:Myotonic Dystrophy / Q000201:enzymology*; D065636:Myotonin-Protein Kinase; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics; D018911:Trinucleotide Repeats
D020413:3' Untranslated Regions; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases