4KI0

Crystal structure of the maltose-binding protein/maltose transporter complex in an outward-facing conformation bound to maltohexaose


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.38 Å
  • R-Value Free: 0.228 
  • R-Value Work: 0.192 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structural basis for substrate specificity in the Escherichia coli maltose transport system.

Oldham, M.L.Chen, S.Chen, J.

(2013) Proc.Natl.Acad.Sci.USA 110: 18132-18137

  • DOI: 10.1073/pnas.1311407110
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • ATP-binding cassette (ABC) transporters are molecular pumps that harness the chemical energy of ATP hydrolysis to translocate solutes across the membrane. The substrates transported by different ABC transporters are diverse, ranging from small ions t ...

    ATP-binding cassette (ABC) transporters are molecular pumps that harness the chemical energy of ATP hydrolysis to translocate solutes across the membrane. The substrates transported by different ABC transporters are diverse, ranging from small ions to large proteins. Although crystal structures of several ABC transporters are available, a structural basis for substrate recognition is still lacking. For the Escherichia coli maltose transport system, the selectivity of sugar binding to maltose-binding protein (MBP), the periplasmic binding protein, does not fully account for the selectivity of sugar transport. To obtain a molecular understanding of this observation, we determined the crystal structures of the transporter complex MBP-MalFGK2 bound with large malto-oligosaccharide in two different conformational states. In the pretranslocation structure, we found that the transmembrane subunit MalG forms two hydrogen bonds with malto-oligosaccharide at the reducing end. In the outward-facing conformation, the transmembrane subunit MalF binds three glucosyl units from the nonreducing end of the sugar. These structural features explain why modified malto-oligosaccharides are not transported by MalFGK2 despite their high binding affinity to MBP. They also show that in the transport cycle, substrate is channeled from MBP into the transmembrane pathway with a polarity such that both MBP and MalFGK2 contribute to the overall substrate selectivity of the system.


    Organizational Affiliation

    Howard Hughes Medical Institute and Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ABC transporter related protein
A, B
381Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: malK
EC: 7.5.2.1
Membrane protein
mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
ATP Binding Cassette (ABC) Transporters
Protein: 
MalFGK2-MBP Maltose uptake transporter complex
Find proteins for P68187 (Escherichia coli (strain K12))
Go to UniProtKB:  P68187
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Maltose-binding periplasmic protein
E
380Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: malE
Membrane protein
mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
ATP Binding Cassette (ABC) Transporters
Protein: 
MalFGK2-MBP Maltose uptake transporter complex
Find proteins for P0AEX9 (Escherichia coli (strain K12))
Go to UniProtKB:  P0AEX9
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Maltose transport system permease protein MalF
F
514Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: malF
Membrane protein
mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
ATP Binding Cassette (ABC) Transporters
Protein: 
MalFGK2-MBP Maltose uptake transporter complex
Find proteins for P02916 (Escherichia coli (strain K12))
Go to UniProtKB:  P02916
Entity ID: 4
MoleculeChainsSequence LengthOrganismDetails
Binding-protein-dependent transport systems inner membrane component
G
296Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: malG
Membrane protein
mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
ATP Binding Cassette (ABC) Transporters
Protein: 
MalFGK2-MBP Maltose uptake transporter complex
Find proteins for P68183 (Escherichia coli (strain K12))
Go to UniProtKB:  P68183
Small Molecules
Ligands 5 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ANP
Query on ANP

Download SDF File 
Download CCD File 
A, B
PHOSPHOAMINOPHOSPHONIC ACID-ADENYLATE ESTER
C10 H17 N6 O12 P3
PVKSNHVPLWYQGJ-KQYNXXCUSA-N
 Ligand Interaction
GLC
Query on GLC

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Download CCD File 
F
ALPHA-D-GLUCOSE
C6 H12 O6
WQZGKKKJIJFFOK-DVKNGEFBSA-N
 Ligand Interaction
MG
Query on MG

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Download CCD File 
A, B
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
UMQ
Query on UMQ

Download SDF File 
Download CCD File 
E, F, G
UNDECYL-MALTOSIDE
UNDECYL-BETA-D-MALTOPYRANOSIDE
C23 H44 O11
UYEMNFYVTFDKRG-ZNGNCRBCSA-N
 Ligand Interaction
PGV
Query on PGV

Download SDF File 
Download CCD File 
F
(1R)-2-{[{[(2S)-2,3-DIHYDROXYPROPYL]OXY}(HYDROXY)PHOSPHORYL]OXY}-1-[(PALMITOYLOXY)METHYL]ETHYL (11E)-OCTADEC-11-ENOATE
PHOSPHATIDYLGLYCEROL, 2-VACCENOYL-1-PALMITOYL-SN-GLYCEROL-3-PHOSPHOGLYCEROL
C40 H77 O10 P
ADYWCMPUNIVOEA-GPJPVTGXSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.38 Å
  • R-Value Free: 0.228 
  • R-Value Work: 0.192 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 81.592α = 85.30
b = 96.631β = 79.11
c = 112.321γ = 73.00
Software Package:
Software NamePurpose
HKL-2000data collection
REFMACrefinement
PHASERphasing
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-10-23
    Type: Initial release
  • Version 1.1: 2013-11-06
    Type: Database references
  • Version 1.2: 2013-11-27
    Type: Database references