2AWO

Crystal structure of the ADP-Mg-bound E. Coli MALK (Crystallized with ADP-Mg)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.277 
  • R-Value Work: 0.239 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

ATP hydrolysis is required to reset the ATP-binding cassette dimer into the resting-state conformation.

Lu, G.Westbrooks, J.M.Davidson, A.L.Chen, J.

(2005) Proc.Natl.Acad.Sci.Usa 102: 17969-17974

  • DOI: 10.1073/pnas.0506039102
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • ATP-binding cassette (ABC) transporters couple ATP binding and hydrolysis to the movement of substances across the membrane; conformational changes clearly play an important role in the transporter mechanism. Previously, we have shown that a dimer of ...

    ATP-binding cassette (ABC) transporters couple ATP binding and hydrolysis to the movement of substances across the membrane; conformational changes clearly play an important role in the transporter mechanism. Previously, we have shown that a dimer of MalK, the ATPase subunit of the maltose transporter from Escherichia coli, undergoes a tweezers-like motion in a transport cycle. The MalK monomer consists of an N-terminal nucleotide binding domain and a C-terminal regulatory domain. The two nucleotide-binding domains in a dimer are either open or closed, depending on whether ATP is present, while the regulatory domains maintain contacts to hold the dimer together. In this work, the structure of MalK in a posthydrolysis state is presented, obtained by cocrystallizing MalK with ATP-Mg(2+). ATP was hydrolyzed in the crystallization drop, and ADP-Mg(2+) was found in the resulting crystal structure. In contrast to the ATP-bound form where two ATP molecules are buried in a closed interface between the nucleotide-binding domains, the two nucleotide-binding domains of the ADP-bound form are open, indicating that ADP, unlike ATP, cannot stabilize the closed form. This conclusion is further supported by oligomerization studies of MalK in solution. At low protein concentrations, ATP promotes dimerization of MalK, whereas ADP does not. The structures of dimeric MalK in the nucleotide-free, ATP-bound, and ADP-bound forms provide a framework for understanding the nature of the conformational changes that occur in an ATP-binding cassette transporter hydrolysis cycle, as well as how conformational changes in MalK are coupled to solute transport.


    Organizational Affiliation

    Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Maltose/maltodextrin import ATP-binding protein malK
A, B, C, D
381Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: malK
EC: 7.5.2.1
Find proteins for P68187 (Escherichia coli (strain K12))
Go to UniProtKB:  P68187
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ADP
Query on ADP

Download SDF File 
Download CCD File 
A, B, C, D
ADENOSINE-5'-DIPHOSPHATE
C10 H15 N5 O10 P2
XTWYTFMLZFPYCI-KQYNXXCUSA-N
 Ligand Interaction
MG
Query on MG

Download SDF File 
Download CCD File 
A, B, C, D
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.277 
  • R-Value Work: 0.239 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 70.213α = 90.00
b = 101.975β = 90.73
c = 131.503γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
AMoREphasing
SCALEPACKdata scaling
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-12-13
    Type: Initial release
  • Version 1.1: 2008-05-01
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Source and taxonomy, Version format compliance