3KJT

Stimulation of the maltose transporter by a mutant sucrose binding protein gives insights into ABC transporter coupling


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.5 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.213 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Studies of the maltose transport system reveal a mechanism for coupling ATP hydrolysis to substrate translocation without direct recognition of substrate.

Gould, A.D.Shilton, B.H.

(2010) J.Biol.Chem. 285: 11290-11296

  • DOI: 10.1074/jbc.M109.089078
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The ATPase activity of the maltose transporter (MalFGK(2)) is dependent on interactions with the maltose-binding protein (MBP). To determine whether direct interactions between the translocated sugar and MalFGK(2) are important for the regulation of ...

    The ATPase activity of the maltose transporter (MalFGK(2)) is dependent on interactions with the maltose-binding protein (MBP). To determine whether direct interactions between the translocated sugar and MalFGK(2) are important for the regulation of ATP hydrolysis, we used an MBP mutant (sMBP) that is able to bind either maltose or sucrose. We observed that maltose- and sucrose-bound sMBP stimulate equal levels of MalFGK(2) ATPase activity. Therefore, the ATPase activity of MalFGK(2) is coupled to translocation of maltose solely by interactions between MalFGK(2) and MBP. For both maltose and sucrose, the ability of sMBP to stimulate the MalFGK(2) ATPase was greatly reduced compared with wild-type MBP, indicating that the mutations in sMBP have interfered with important interactions between MBP and MalFGK(2). High resolution crystal structure analysis of sMBP shows that in the closed conformation with bound sucrose, three of four mutations are buried, and the fourth causes only a minor change in the accessible surface. In contrast, in the open form of sMBP, all of the mutations are accessible, and the main chain of Tyr(62)-Gly(69) is destabilized and occupies an alternative conformation due to the W62Y mutation. On this basis, the compromised ability of sMBP to stimulate ATP hydrolysis by MalFGK(2) is most likely due to a disruption of interactions between MalFGK(2) and the open, rather than the closed, conformation of sMBP. Modeling the open sMBP structure bound to MalFGK(2) in the transition state for ATP hydrolysis points to an important site of interaction and suggests a mechanism for coupling ATP hydrolysis to substrate translocation that is independent of the exact structure of the substrate.


    Organizational Affiliation

    Department of Biochemistry, University of Western Ontario, London, Ontario N6B 2G3, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Maltose-binding periplasmic protein
A
372Escherichia coli (strain K12)Mutation(s): 4 
Gene Names: malE
Find proteins for P0AEX9 (Escherichia coli (strain K12))
Go to UniProtKB:  P0AEX9
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.5 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.213 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 43.890α = 90.00
b = 65.540β = 101.14
c = 57.500γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
CNSphasing
HKL-2000data collection
HKL-2000data reduction
PDB_EXTRACTdata extraction
SCALAdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-02-09
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance