Structural and mechanistic insights into nuclear transport and delivery of the critical pluripotency factor Oct4 to DNA.
Oct4 is a master regulator of the induction and maintenance of cellular pluripotency, and has crucial roles in early stages of differentiation. It is the only factor that cannot be substituted by other members of the same protein family to induce pluripotency. However, although Oct4 nuclear transport and delivery to target DNA are critical events for reprogramming to pluripotency, little is known about the molecular mechanism. Oct4 is imported to the nucleus by the classical nuclear transport mechanism, which requires importin α as an adaptor to bind the nuclear localization signal (NLS). Although there are structures of complexes of the NLS of transcription factors (TFs) in complex with importin α, there are no structures available for complexes involving intact TFs. We have therefore modeled the structure of the complex of the whole Oct4 POU domain and importin α2 using protein-protein docking and molecular dynamics. The model explains how the Ebola virus VP24 protein has a negative effect on the nuclear import of STAT1 by importin α but not on Oct4, and how Nup 50 facilitates cargo release from importin α. The model demonstrates the structural differences between the Oct4 importin α bound and DNA bound crystal states. We propose that the 'expanded linker' between the two DNA-binding domains of Oct4 is an intrinsically disordered region and that its conformational changes have a key role in the recognition/binding to both DNA and importin α. Moreover, we propose that this structural change enables efficient delivery to DNA after release from importin α.
a Graduate School of Integrated Basic Sciences , Nihon University , 3-25-40 Sakurajousui, Setagaya-ku, Tokyo 156-8550 , Japan.
Takahide
T
Okuyama
b Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences , Nihon University , 3-25-40 Sakurajousui, Setagaya, Tokyo 156-8550 , Japan.|c National Institutes of Biomedical Innovation, Health and Nutrition , 7-6-8 Saito-Asagi, Ibaraki, Osaka 675-0085 , Japan.
Ryosuke
R
Yamagishi
b Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences , Nihon University , 3-25-40 Sakurajousui, Setagaya, Tokyo 156-8550 , Japan.
Jiro
J
Shimada
b Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences , Nihon University , 3-25-40 Sakurajousui, Setagaya, Tokyo 156-8550 , Japan.
Masaaki
M
Ikeda
b Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences , Nihon University , 3-25-40 Sakurajousui, Setagaya, Tokyo 156-8550 , Japan.
Yayoi
Y
Maruoka
a Graduate School of Integrated Basic Sciences , Nihon University , 3-25-40 Sakurajousui, Setagaya-ku, Tokyo 156-8550 , Japan.|b Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences , Nihon University , 3-25-40 Sakurajousui, Setagaya, Tokyo 156-8550 , Japan.|c National Institutes of Biomedical Innovation, Health and Nutrition , 7-6-8 Saito-Asagi, Ibaraki, Osaka 675-0085 , Japan.
Hiroki
0000-0002-7930-1038
H
Kaneko
D021581:Active Transport, Cell Nucleus / Q000235:genetics; D001665:Binding Sites; D002467:Cell Nucleus / Q000737:chemistry / Q000235:genetics; D065150:Cellular Reprogramming / Q000235:genetics; D029043:Ebolavirus / Q000737:chemistry / Q000235:genetics / Q000472:pathogenicity; D019142:Hemorrhagic Fever, Ebola / Q000235:genetics* / Q000821:virology; D006801:Humans; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics; D019913:Nuclear Localization Signals / Q000737:chemistry / Q000235:genetics; D050814:Octamer Transcription Factor-3 / Q000737:chemistry* / Q000235:genetics; D011485:Protein Binding; D060066:Protein Interaction Maps; D050794:STAT1 Transcription Factor / Q000737:chemistry / Q000235:genetics; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics; D028901:alpha Karyopherins / Q000737:chemistry* / Q000235:genetics
D046912:Multiprotein Complexes; D019913:Nuclear Localization Signals; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D050794:STAT1 Transcription Factor; C446938:VP24 protein, Ebola virus; D014764:Viral Proteins; D028901:alpha Karyopherins; C087978:karyopherin alpha 2
DNA delivery; Oct4; importin α; nuclear transport; protein docking study