4S3Q

Amylomaltase MalQ from Escherichia coli in complex with maltose


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.223 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Structural Basis for the Interconversion of Maltodextrins by MalQ, the Amylomaltase of Escherichia coli.

Weiss, S.C.Skerra, A.Schiefner, A.

(2015) J Biol Chem 290: 21352-21364

  • DOI: 10.1074/jbc.M115.667337
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • Amylomaltase MalQ is essential for the metabolism of maltose and maltodextrins in Escherichia coli. It catalyzes transglycosylation/disproportionation reactions in which glycosyl or dextrinyl units are transferred among linear maltodextrins of variou ...

    Amylomaltase MalQ is essential for the metabolism of maltose and maltodextrins in Escherichia coli. It catalyzes transglycosylation/disproportionation reactions in which glycosyl or dextrinyl units are transferred among linear maltodextrins of various lengths. To elucidate the molecular basis of transglycosylation by MalQ, we have determined three crystal structures of this enzyme, i.e. the apo-form, its complex with maltose, and an inhibitor complex with the transition state analog acarviosine-glucose-acarbose, at resolutions down to 2.1 Å. MalQ represents the first example of a mesophilic bacterial amylomaltase with known structure and exhibits an N-terminal extension of about 140 residues, in contrast with previously described thermophilic enzymes. This moiety seems unique to amylomaltases from Enterobacteriaceae and folds into two distinct subdomains that associate with different parts of the catalytic core. Intriguingly, the three MalQ crystal structures appear to correspond to distinct states of this enzyme, revealing considerable conformational changes during the catalytic cycle. In particular, the inhibitor complex highlights the requirement of both a 3-OH group and a 4-OH group (or α1-4-glycosidic bond) at the acceptor subsite +1 for the catalytically competent orientation of the acid/base catalyst Glu-496. Using an HPLC-based MalQ enzyme assay, we could demonstrate that the equilibrium concentration of maltodextrin products depends on the length of the initial substrate; with increasing numbers of glycosidic bonds, less glucose is formed. Thus, both structural and enzymatic data are consistent with the extremely low hydrolysis rates observed for amylomaltases and underline the importance of MalQ for the metabolism of maltodextrins in E. coli.


    Organizational Affiliation

    From the Lehrstuhl für Biologische Chemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85350 Freising-Weihenstephan, Germany schiefner@wzw.tum.de.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
4-alpha-glucanotransferase
A, B, C
696Escherichia coli K-12Mutation(s): 0 
Gene Names: b3416JW3379malAmalQ
EC: 2.4.1.25
Find proteins for P15977 (Escherichia coli (strain K12))
Go to UniProtKB:  P15977
Protein Feature View
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MAL
Query on MAL

Download CCD File 
A
MALTOSE
C12 H22 O11
GUBGYTABKSRVRQ-ASMJPISFSA-N
 Ligand Interaction
IOD
Query on IOD

Download CCD File 
A, B, C
IODIDE ION
I
XMBWDFGMSWQBCA-UHFFFAOYSA-M
 Ligand Interaction
EDO
Query on EDO

Download CCD File 
A, B, C
1,2-ETHANEDIOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.223 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 75.132α = 76.11
b = 77.019β = 75.48
c = 128.403γ = 66.31
Software Package:
Software NamePurpose
XSCALEdata scaling
REFMACrefinement
PDB_EXTRACTdata extraction
MAR345data collection
XDSdata reduction
PHASERphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2015-07-08
    Type: Initial release
  • Version 1.1: 2015-07-15
    Changes: Database references
  • Version 1.2: 2015-09-16
    Changes: Database references
  • Version 1.3: 2017-11-22
    Changes: Refinement description