Crystal Structure of Importin-alpha from Neurospora crassa complexed with SV40NLS

Experimental Data Snapshot

  • Resolution: 1.76 Å
  • R-Value Free: 0.211 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.184 

Starting Model: experimental
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Structure of Importin-alpha from a Filamentous Fungus in Complex with a Classical Nuclear Localization Signal.

Bernardes, N.E.Takeda, A.A.Dreyer, T.R.Freitas, F.Z.Bertolini, M.C.Fontes, M.R.

(2015) PLoS One 10: e0128687-e0128687

  • DOI: https://doi.org/10.1371/journal.pone.0128687
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Neurospora crassa is a filamentous fungus that has been extensively studied as a model organism for eukaryotic biology, providing fundamental insights into cellular processes such as cell signaling, growth and differentiation. To advance in the study of this multicellular organism, an understanding of the specific mechanisms for protein transport into the cell nucleus is essential. Importin-α (Imp-α) is the receptor for cargo proteins that contain specific nuclear localization signals (NLSs) that play a key role in the classical nuclear import pathway. Structures of Imp-α from different organisms (yeast, rice, mouse, and human) have been determined, revealing that this receptor possesses a conserved structural scaffold. However, recent studies have demonstrated that the Impα mechanism of action may vary significantly for different organisms or for different isoforms from the same organism. Therefore, structural, functional, and biophysical characterization of different Impα proteins is necessary to understand the selectivity of nuclear transport. Here, we determined the first crystal structure of an Impα from a filamentous fungus which is also the highest resolution Impα structure already solved to date (1.75 Å). In addition, we performed calorimetric analysis to determine the affinity and thermodynamic parameters of the interaction between Imp-α and the classical SV40 NLS peptide. The comparison of these data with previous studies on Impα proteins led us to demonstrate that N. crassa Imp-α possess specific features that are distinct from mammalian Imp-α but exhibit important similarities to rice Imp-α, particularly at the minor NLS binding site.

  • Organizational Affiliation

    Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista, UNESP, Botucatu, SP, Brazil.

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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Importin subunit alphaA [auth B]495Neurospora crassaMutation(s): 0 
Gene Names: 3H10.030
Find proteins for Q9C2K9 (Neurospora crassa)
Explore Q9C2K9 
Go to UniProtKB:  Q9C2K9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9C2K9
Sequence Annotations
  • Reference Sequence

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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Large T antigenB [auth A],
8Betapolyomavirus macacaeMutation(s): 0 
EC: 3.6.4
Find proteins for P03070 (Simian virus 40)
Explore P03070 
Go to UniProtKB:  P03070
Entity Groups  
UniProt GroupP03070
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.76 Å
  • R-Value Free: 0.211 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.184 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 45.127α = 90
b = 64.494β = 90
c = 185.65γ = 90
Software Package:
Software NamePurpose
CBASSdata collection
PHENIXmodel building
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-07-01
    Type: Initial release
  • Version 1.1: 2023-09-20
    Changes: Data collection, Database references, Refinement description