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 
  • R-Value Observed: 0.194 

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This is version 2.0 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 U S A 110: 18132-18137

  • DOI: 10.1073/pnas.1311407110
  • Primary Citation of Related Structures:  
    4KHZ, 4KI0

  • 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 to large proteins ...

    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
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
ABC transporter related proteinA, B381Escherichia coli DH1Mutation(s): 0 
Gene Names: ECDH1ME8569_3891EcDH1_3960malK
EC: 7.5.2.1
Membrane Entity: Yes 
UniProt
Find proteins for P68187 (Escherichia coli (strain K12))
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Go to UniProtKB:  P68187
Entity Groups  
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UniProt GroupP68187
Protein Feature View
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Maltose-binding periplasmic proteinC [auth E]380Escherichia coli K-12Mutation(s): 0 
Gene Names: b4034JW3994malE
Membrane Entity: Yes 
UniProt
Find proteins for P0AEX9 (Escherichia coli (strain K12))
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UniProt GroupP0AEX9
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Maltose transport system permease protein MalFD [auth F]514Escherichia coli K-12Mutation(s): 0 
Gene Names: b4033JW3993malF
Membrane Entity: Yes 
UniProt
Find proteins for P02916 (Escherichia coli (strain K12))
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UniProt GroupP02916
Protein Feature View
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Entity ID: 4
MoleculeChainsSequence LengthOrganismDetailsImage
Binding-protein-dependent transport systems inner membrane componentE [auth G]296Escherichia coli DH1Mutation(s): 0 
Gene Names: ECDH1ME8569_3888EcDH1_3964malG
Membrane Entity: Yes 
UniProt
Find proteins for P68183 (Escherichia coli (strain K12))
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UniProt GroupP68183
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Oligosaccharides

Help

Entity ID: 5
MoleculeChainsChain Length2D DiagramGlycosylation3D Interactions
alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranoseF [auth C]4N/A Oligosaccharides Interaction
Glycosylation Resources
GlyTouCan:  G87171PZ
GlyCosmos:  G87171PZ
GlyGen:  G87171PZ
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PGV
Query on PGV

Download Ideal Coordinates CCD File 
L [auth F],
M [auth F]
(1R)-2-{[{[(2S)-2,3-DIHYDROXYPROPYL]OXY}(HYDROXY)PHOSPHORYL]OXY}-1-[(PALMITOYLOXY)METHYL]ETHYL (11E)-OCTADEC-11-ENOATE
C40 H77 O10 P
ADYWCMPUNIVOEA-GPJPVTGXSA-N
 Ligand Interaction
ANP
Query on ANP

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H [auth A],
J [auth B]
PHOSPHOAMINOPHOSPHONIC ACID-ADENYLATE ESTER
C10 H17 N6 O12 P3
PVKSNHVPLWYQGJ-KQYNXXCUSA-N
 Ligand Interaction
UMQ
Query on UMQ

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K [auth E],
N [auth F],
O [auth F],
P [auth F],
Q [auth G],
K [auth E],
N [auth F],
O [auth F],
P [auth F],
Q [auth G],
R [auth G],
S [auth G],
T [auth G],
U [auth G],
V [auth G],
W [auth G]
UNDECYL-MALTOSIDE
C23 H44 O11
UYEMNFYVTFDKRG-ZNGNCRBCSA-N
 Ligand Interaction
MG
Query on MG

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G [auth A],
I [auth B]
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Biologically Interesting Molecules (External Reference) 1 Unique
Entity ID: 5
IDChainsNameType/Class2D Diagram3D Interactions
PRD_900010
Query on PRD_900010
F [auth C]alpha-maltotetraoseOligosaccharide / Substrate analog 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 
  • R-Value Observed: 0.194 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 81.592α = 85.3
b = 96.631β = 79.11
c = 112.321γ = 73
Software Package:
Software NamePurpose
HKL-2000data collection
PHASERphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-10-23
    Type: Initial release
  • Version 1.1: 2013-11-06
    Changes: Database references
  • Version 1.2: 2013-11-27
    Changes: Database references
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Atomic model, Data collection, Database references, Derived calculations, Structure summary