3JZJ

Crystal structures of the GacH receptor of Streptomyces glaucescens GLA.O in the unliganded form and in complex with acarbose and an acarbose homolog. Comparison with acarbose-loaded maltose binding protein of Salmonella typhimurium.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.40 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.201 
  • R-Value Observed: 0.203 

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This is version 2.1 of the entry. See complete history


Literature

Crystal Structures of the Solute Receptor GacH of Streptomyces glaucescens in Complex with Acarbose and an Acarbose Homolog: Comparison with the Acarbose-Loaded Maltose-Binding Protein of Salmonella typhimurium.

Vahedi-Faridi, A.Licht, A.Bulut, H.Scheffel, F.Keller, S.Wehmeier, U.F.Saenger, W.Schneider, E.

(2010) J Mol Biol 397: 709-723

  • DOI: https://doi.org/10.1016/j.jmb.2010.01.054
  • Primary Citation of Related Structures:  
    3JYR, 3JZJ, 3K00, 3K01, 3K02

  • PubMed Abstract: 

    GacH is the solute binding protein (receptor) of the putative oligosaccharide ATP-binding cassette transporter GacFG, encoded in the acarbose biosynthetic gene cluster (gac) from Streptomyces glaucescens GLA.O. In the context of the proposed function of acarbose (acarviosyl-1,4-maltose) as a 'carbophor,' the transporter, in complex with a yet to be identified ATPase subunit, is supposed to mediate the uptake of longer acarbose homologs and acarbose for recycling purposes. Binding assays using isothermal titration calorimetry identified GacH as a maltose/maltodextrin-binding protein with a low affinity for acarbose but with considerable binding activity for its homolog, component 5C (acarviosyl-1,4-maltose-1,4-glucose-1,1-glucose). In contrast, the maltose-binding protein of Salmonella typhimurium (MalE) displays high-affinity acarbose binding. We determined the crystal structures of GacH in complex with acarbose, component 5C, and maltotetraose, as well as in unliganded form. As found for other solute receptors, the polypeptide chain of GacH is folded into two distinct domains (lobes) connected by a hinge, with the interface between the lobes forming the substrate-binding pocket. GacH does not specifically bind the acarviosyl group, but displays specificity for binding of the maltose moiety in the inner part of its binding pocket. The crystal structure of acarbose-loaded MalE showed that two glucose units of acarbose are bound at the same region and position as maltose. A comparative analysis revealed that in GacH, acarbose is buried deeper into the binding pocket than in MalE by exactly one glucose ring shift, resulting in a total of 18 hydrogen-bond interactions versus 21 hydrogen-bond interactions for MalE(acarbose). Since the substrate specificity of ATP-binding cassette import systems is determined by the cognate binding protein, our results provide the first biochemical and structural evidence for the proposed role of GacHFG in acarbose metabolism.


  • Organizational Affiliation

    Institut für Chemie und Biochemie/Kristallographie, Freie Universität Berlin, Berlin, Germany.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Acarbose/maltose binding protein GacH409Streptomyces glaucescensMutation(s): 0 
Gene Names: gacH
UniProt
Find proteins for B0B0V1 (Streptomyces glaucescens)
Explore B0B0V1 
Go to UniProtKB:  B0B0V1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupB0B0V1
Sequence Annotations
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  • Reference Sequence
Oligosaccharides

Help

Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
4,6-dideoxy-4-{[(1S,4R,5S,6S)-4,5,6-trihydroxy-3-(hydroxymethyl)cyclohex-2-en-1-yl]amino}-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose
B
3N/AN/A
Glycosylation Resources
GlyTouCan:  G66431MI
GlyCosmos:  G66431MI
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download Ideal Coordinates CCD File 
C [auth A]SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
Biologically Interesting Molecules (External Reference) 1 Unique
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.40 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.201 
  • R-Value Observed: 0.203 
  • Space Group: P 41 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 72.093α = 90
b = 72.093β = 90
c = 160.386γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
MOLREPphasing
REFMACrefinement
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-02-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Refinement description, Version format compliance
  • Version 1.2: 2017-11-01
    Changes: Advisory, Refinement description
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Database references, Derived calculations, Non-polymer description, Structure summary
  • Version 2.1: 2024-02-21
    Changes: Advisory, Data collection, Database references, Structure summary