5TBK

Crystal structure of human importin a3 bound to RCC1


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.45 Å
  • R-Value Free: 0.296 
  • R-Value Work: 0.278 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Three-dimensional context rather than NLS amino acid sequence determines importin alpha subtype specificity for RCC1.

Sankhala, R.S.Lokareddy, R.K.Begum, S.Pumroy, R.A.Gillilan, R.E.Cingolani, G.

(2017) Nat Commun 8: 979-979

  • DOI: 10.1038/s41467-017-01057-7
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Active nuclear import of Ran exchange factor RCC1 is mediated by importin α3. This pathway is essential to generate a gradient of RanGTP on chromatin that directs nucleocytoplasmic transport, mitotic spindle assembly and nuclear envelope formation. H ...

    Active nuclear import of Ran exchange factor RCC1 is mediated by importin α3. This pathway is essential to generate a gradient of RanGTP on chromatin that directs nucleocytoplasmic transport, mitotic spindle assembly and nuclear envelope formation. Here we identify the mechanisms of importin α3 selectivity for RCC1. We find this isoform binds RCC1 with one order of magnitude higher affinity than the generic importin α1, although the two isoforms share an identical NLS-binding groove. Importin α3 uses its greater conformational flexibility to wedge the RCC1 β-propeller flanking the NLS against its lateral surface, preventing steric clashes with its Armadillo-core. Removing the β-propeller, or inserting a linker between NLS and β-propeller, disrupts specificity for importin α3, demonstrating the structural context rather than NLS sequence determines selectivity for isoform 3. We propose importin α3 evolved to recognize topologically complex NLSs that lie next to bulky domains or are masked by quaternary structures.Importin α3 facilitates the nuclear transport of the Ran guanine nucleotide exchange factor RCC1. Here the authors reveal the molecular basis for the selectivity of RCC1 for importin α3 vs the generic importin α1 and discuss the evolution of importin α isoforms.


    Organizational Affiliation

    Department of Biochemistry, University of Utah, 15N Medical Drive East, Salt Lake City, UT, 84112-5650, USA.,Institute of Biomembranes and Bioenergetics, National Research Council, Via Amendola 165/A, Bari, 70126, Italy. gino.cingolani@jefferson.edu.,Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA, 19107, USA.,Macromolecular Diffraction Facility, Cornell High Energy Synchrotron Source (MacCHESS), Cornell University, 161 Synchrotron Drive, Ithaca, NY, 14853, USA.,Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA, 19107, USA. gino.cingolani@jefferson.edu.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Importin subunit alpha-3
A, B, C, D, E, F, G, H
521Homo sapiensMutation(s): 0 
Gene Names: KPNA4 (QIP1)
Find proteins for O00629 (Homo sapiens)
Go to Gene View: KPNA4
Go to UniProtKB:  O00629
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Regulator of chromosome condensation
I, K, L, M, N, O, P, J
421Homo sapiensMutation(s): 0 
Gene Names: RCC1 (CHC1)
Find proteins for P18754 (Homo sapiens)
Go to Gene View: RCC1
Go to UniProtKB:  P18754
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.45 Å
  • R-Value Free: 0.296 
  • R-Value Work: 0.278 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 127.403α = 75.65
b = 162.494β = 85.63
c = 161.592γ = 72.17
Software Package:
Software NamePurpose
PHASERphasing
HKL-2000data scaling
HKL-2000data reduction
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical SciencesUnited StatesGM074846
National Institutes of Health/National Institute of General Medical SciencesUnited StatesGM100888

Revision History 

  • Version 1.0: 2017-09-13
    Type: Initial release
  • Version 1.1: 2017-10-04
    Type: Author supporting evidence
  • Version 1.2: 2017-11-01
    Type: Author supporting evidence, Database references