Unusual Topological RNA Architecture with an Eight-Stranded Helical Fragment Containing A-, G-, and U-Tetrads.
Human telomeric RNA performs various cellular functions such as telomere length regulation, heterochromatin formation, and chromosome end protection. Using a combination of nuclear magnetic resonance, circular dichroism, and gel electrophoresis, we observed an unusual topological structure formed by human telomere RNA r(GUUAGGGU). Our results showed that every set of four strands formed a parallel G-quadruplex as symmetry-related units containing four G-tetrads, two U-tetrads, and one A-tetrad. An eight-stranded helical fragment containing A-, G-, and U-tetrads provided a central intercalated scaffold that connected two G-quadruplex units in an alternating antiparallel arrangement, giving rise to a novel RNA architecture. This higher order RNA structure is so stable that it would be surprising if similar structures do not occur in nature. Our findings provide a new insight into the behavior of human telomeric RNA molecules.
Division of Chemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki , 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
Chao-Da
CD
Xiao
Division of Chemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki , 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
Takumi
T
Ishizuka
Division of Chemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki , 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
Xiao-Qing
XQ
Zhu
Department of Chemistry, Graduate School of Science, Kyoto University , Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
Yue
Y
Li
Department of Chemistry, Graduate School of Science, Kyoto University , Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
Hiroshi
H
Sugiyama
Division of Chemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki , 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
Yan
0000-0003-0379-8866
Y
Xu
D000225:Adenine / Q000737:chemistry*; D054856:G-Quadruplexes; D006801:Humans; D008958:Models, Molecular; D012313:RNA / Q000737:chemistry*; D020871:RNA Stability; D016615:Telomere / Q000737:chemistry*; D014529:Uridine / Q000737:chemistry*
D012313:RNA; D000225:Adenine; D014529:Uridine