A high-resolution structure of the pre-microRNA nuclear export machinery.
Nuclear export of microRNAs (miRNAs) by exportin-5 (Exp-5) is an essential step in miRNA biogenesis. Here, we present the 2.9 angstrom structure of the pre-miRNA nuclear export machinery formed by pre-miRNA complexed with Exp-5 and a guanine triphosphate (GTP)-bound form of the small nuclear guanine triphosphatase (GTPase) Ran (RanGTP). The x-ray structure shows that Exp-5:RanGTP recognizes the 2-nucleotide 3' overhang structure and the double-stranded stem of the pre-miRNA. Exp-5:RanGTP shields the pre-miRNA stem from degradation in a baseball mitt-like structure where it is held by broadly distributed weak interactions, whereas a tunnel-like structure of Exp-5 interacts strongly with the 2-nucleotide 3' overhang through hydrogen bonds and ionic interactions. RNA recognition by Exp-5:RanGTP does not depend on RNA sequence, implying that Exp-5:RanGTP can recognize a variety of pre-miRNAs.
Okada
Chimari
C
Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
Yamashita
Eiki
E
Lee
Soo Jae
SJ
Shibata
Satoshi
S
Katahira
Jun
J
Nakagawa
Atsushi
A
Yoneda
Yoshihiro
Y
Tsukihara
Tomitake
T
D021581:Active Transport, Cell Nucleus; D000818:Animals; D001665:Binding Sites; D055598:Chemical Phenomena; D003460:Crystallization; D018360:Crystallography, X-Ray; D004285:Dogs; D006801:Humans; D006860:Hydrogen Bonding; D028884:Karyopherins / Q000737:chemistry* / Q000378:metabolism; D035683:MicroRNAs / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D020931:ran GTP-Binding Protein / Q000737:chemistry / Q000378:metabolism
D028884:Karyopherins; D035683:MicroRNAs; C446511:XPO5 protein, human; D020931:ran GTP-Binding Protein