Crystal structure of E. coli MalK in the nucleotide-free form

Experimental Data Snapshot

  • Resolution: 2.80 Å
  • R-Value Free: 0.304 
  • R-Value Work: 0.249 
  • R-Value Observed: 0.249 

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A tweezer-like motion of the ATP-binding cassette dimer in an ABC transport cycle

Chen, J.Lu, G.Lin, J.Davidson, A.L.Quiocho, F.A.

(2003) Mol Cell 12: 651-661

  • DOI: https://doi.org/10.1016/j.molcel.2003.08.004
  • Primary Citation of Related Structures:  
    1Q12, 1Q1B, 1Q1E

  • PubMed Abstract: 

    The ATPase components of ATP binding cassette (ABC) transporters power the transporters by binding and hydrolyzing ATP. Major conformational changes of an ATPase are revealed by crystal structures of MalK, the ATPase subunit of the maltose transporter from Escherichia coli, in three different dimeric configurations. While other nucleotide binding domains or subunits display low affinity for each other in the absence of the transmembrane segments, the MalK dimer is stabilized through interactions of the additional C-terminal domains. In the two nucleotide-free structures, the N-terminal nucleotide binding domains are separated to differing degrees, and the dimer is maintained through contacts of the C-terminal regulatory domains. In the ATP-bound form, the nucleotide binding domains make contact and two ATPs lie buried along the dimer interface. The two nucleotide binding domains of the dimer open and close like a pair of tweezers, suggesting a regulatory mechanism for ATPase activity that may be tightly coupled to translocation.

  • Organizational Affiliation

    Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA . chenjue@bilbo.bio.purdue.edu

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Maltose/maltodextrin transport ATP-binding protein malK
A, B, C, D
381Escherichia coli K-12Mutation(s): 0 
Gene Names: MALK OR B4035 OR Z5633 OR ECS5018
Find proteins for P68187 (Escherichia coli (strain K12))
Explore P68187 
Go to UniProtKB:  P68187
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP68187
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.80 Å
  • R-Value Free: 0.304 
  • R-Value Work: 0.249 
  • R-Value Observed: 0.249 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.617α = 77.63
b = 93.54β = 79.38
c = 99.796γ = 73.2
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-09-30
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.3: 2024-02-14
    Changes: Data collection, Database references