PDBsum entry 4b8p

Protein transport

PDB id: 4b8p

Contents

Protein chains

421 a.a.

Ligands

THR-VAL-LEU-GLY-LYS-ARG-LYS ×2

Waters ×220

PDB id:

4b8p

Name:

Protein transport

Title:

Rimp_alpha_a89nls

Structure:

Importin subunit alpha-1a. Chain: a, b. Fragment: nls binding domain, residues 73-526. Engineered: yes. A89nls. Chain: c, d. Engineered: yes

Source:

Oryza sativa japonica group. Japanese rice. Organism_taxid: 39947. Expressed in: escherichia coli. Expression_system_taxid: 469008. Synthetic construct. Organism_taxid: 32630.

Resolution:

2.30Å R-factor: 0.190 R-free: 0.204

Authors:

C.-W.Chang,R.L.M.Counago,S.J.Williams,M.Boden,B.Kobe

Key ref:

C.W.Chang et al. (2012). Crystal structure of rice importin-α and structural basis of its interaction with plant-specific nuclear localization signals. Plant Cell, 24, 5074-5088. PubMed id: 23250448

Date:

29-Aug-12 Release date: 09-Jan-13

Protein chains

Q71VM4  (IMA1A_ORYSJ) -  Importin subunit alpha-1a from Oryza sativa subsp. japonica

Seq: 526 a.a.

Struc: 421 a.a.

Enzyme reactions

• Enzyme class: E.C.?

Plant Cell 24:5074-5088 (2012)

PubMed id: 23250448

Crystal structure of rice importin-α and structural basis of its interaction with plant-specific nuclear localization signals.

C.W.Chang, R.L.Couñago, S.J.Williams, M.Bodén, B.Kobe.

ABSTRACT

In the classical nucleocytoplasmic import pathway, nuclear localization signals (NLSs) in cargo proteins are recognized by the import receptor importin-α. Importin-α has two separate NLS binding sites (the major and the minor site), both of which recognize positively charged amino acid clusters in NLSs. Little is known about the molecular basis of the unique features of the classical nuclear import pathway in plants. We determined the crystal structure of rice (Oryza sativa) importin-α1a at 2-Å resolution. The structure reveals that the autoinhibitory mechanism mediated by the importin-β binding domain of importin-α operates in plants, with NLS-mimicking sequences binding to both minor and major NLS binding sites. Consistent with yeast and mammalian proteins, rice importin-α binds the prototypical NLS from simian virus 40 large T-antigen preferentially at the major NLS binding site. We show that two NLSs, previously described as plant specific, bind to and are functional with plant, mammalian, and yeast importin-α proteins but interact with rice importin-α more strongly. The crystal structures of their complexes with rice importin-α show that they bind to the minor NLS binding site. By contrast, the crystal structures of their complexes with mouse (Mus musculus) importin-α show preferential binding to the major NLS binding site. Our results reveal the molecular basis of a number of features of the classical nuclear transport pathway specific to plants.