Crystal structure of MalK, the ATPase subunit of the trehalose/maltose ABC transporter of the archaeon Thermococcus litoralis

EMBO J. 2000 Nov 15;19(22):5951-61. doi: 10.1093/emboj/19.22.5951.


The members of the ABC transporter family transport a wide variety of molecules into or out of cells and cellular compartments. Apart from a translocation pore, each member possesses two similar nucleoside triphosphate-binding subunits or domains in order to couple the energy-providing reaction with transport. In the maltose transporter of several Gram-negative bacteria and the archaeon Thermo coccus litoralis, the nucleoside triphosphate-binding subunit contains a C-terminal regulatory domain. A dimer of the subunit is attached cytoplasmically to the translocation pore. Here we report the crystal structure of this dimer showing two bound pyrophosphate molecules at 1.9 A resolution. The dimer forms by association of the ATPase domains, with the two regulatory domains attached at opposite poles. Significant deviation from 2-fold symmetry is seen at the interface of the dimer and in the regions corresponding to those residues known to be in contact with the translocation pore. The structure and its relationship to function are discussed in the light of known mutations from the homologous Escherichia coli and Salmonella typhimurium proteins.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry*
  • ATP-Binding Cassette Transporters / genetics
  • Adenosine Triphosphatases / chemistry*
  • Adenosine Triphosphatases / genetics
  • Amino Acid Sequence
  • Archaeal Proteins / chemistry
  • Archaeal Proteins / genetics
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Binding Sites
  • Carrier Proteins / chemistry
  • Crystallization
  • Crystallography, X-Ray
  • Dimerization
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Escherichia coli Proteins*
  • Maltose-Binding Proteins
  • Models, Molecular
  • Molecular Sequence Data
  • Monosaccharide Transport Proteins*
  • Protein Structure, Tertiary
  • Protein Subunits
  • Salmonella typhimurium / enzymology
  • Salmonella typhimurium / genetics
  • Sequence Homology, Amino Acid
  • Thermococcus / enzymology*
  • Thermococcus / genetics


  • ATP-Binding Cassette Transporters
  • Archaeal Proteins
  • Bacterial Proteins
  • Carrier Proteins
  • Escherichia coli Proteins
  • MalG protein, E coli
  • MalK protein, Bacteria
  • MalK protein, E coli
  • MalK protein, Salmonella typhimurium
  • Maltose-Binding Proteins
  • Monosaccharide Transport Proteins
  • Protein Subunits
  • maltose transport system, E coli
  • Adenosine Triphosphatases