6N88

Cryo-EM structure of the Importin7:Importin beta:Histone H1.0 complex

Summary for 6N88

• Entry DOI: 10.2210/pdb6n88/pdb
• Related: 6N89
• EMDB information: 0366 0367 0368
• Descriptor: MGC52556 protein, Importin subunit beta-1, Histone H1.0 (3 entities in total)
• Functional Keywords: imp7:impb:h1.0, importin, histone h1, nuclear import, disordered interactions, transport protein
• Biological source: Xenopus laevis (African clawed frog); More
• Total number of polymer chains: 3
• Total formula weight: 237738.15

Authors

Bilokapic, S.,Ivic, N.,Halic, M. (deposition date: 2018-11-28, release date: 2019-02-27, Last modification date: 2024-03-20)

Primary citation

Ivic, N.,Potocnjak, M.,Solis-Mezarino, V.,Herzog, F.,Bilokapic, S.,Halic, M.
Fuzzy Interactions Form and Shape the Histone Transport Complex.
Mol. Cell, 73:1191-, 2019

PubMed Abstract: Protein transport into the nucleus is mediated by transport receptors. Import of highly charged proteins, such as histone H1 and ribosomal proteins, requires a dimer of two transport receptors. In this study, we determined the cryo-EM structure of the Imp7:Impβ:H1.0 complex, showing that the two importins form a cradle that accommodates the linker histone. The H1.0 globular domain is bound to Impβ, whereas the acidic loops of Impβ and Imp7 chaperone the positively charged C-terminal tail. Although it remains disordered, the H1 tail serves as a zipper that closes and stabilizes the structure through transient non-specific interactions with importins. Moreover, we found that the GGxxF and FxFG motifs in the Imp7 C-terminal tail are essential for Imp7:Impβ dimerization and H1 import, resembling importin interaction with nucleoporins, which, in turn, promote complex disassembly. The architecture of many other complexes might be similarly defined by rapidly exchanging electrostatic interactions mediated by disordered regions.

PubMed: 30824373
DOI: 10.1016/j.molcel.2019.01.032

Experimental method

ELECTRON MICROSCOPY (6.2 Å)