Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors and generated by PISA (software)

Biological Assembly 2  

 3D View: Structure | Electron Density | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 2 assigned by authors and generated by PISA (software)

Biological Assembly 3  

 3D View: Structure | Electron Density | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 3 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 238.62 kDa 
• Atom Count: 16868 
• Modelled Residue Count: 2049 
• Deposited Residue Count: 2088 
• Unique protein chains: 1

4S3Q

Amylomaltase MalQ from Escherichia coli in complex with maltose

• DOI: 10.2210/pdb4S3Q/pdb

• Classification: TRANSFERASE
• Organism(s): Escherichia coli K-12
• Expression System: Escherichia coli BL21
• Mutation(s): No 


• Deposited: 2015-03-26 Released: 2015-07-08 
• Deposition Author(s): Weiss, S.C., Schiefner, A.

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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 

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

• PubMed: 26139606 
• DOI: 10.1074/jbc.M115.667337
• Primary Citation of Related Structures:  
  4S3P, 4S3Q, 4S3R


• 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 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.

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Organizational Affiliation: 

From the Lehrstuhl für Biologische Chemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85350 Freising-Weihenstephan, Germany [e-mail].

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
4-alpha-glucanotransferase	A, B, C	696	Escherichia coli K-12	Mutation(s): 0  Gene Names: b3416, JW3379, malA, malQ EC: 2.4.1.25
Find proteins for P15977 (Escherichia coli (strain K12)) Explore P15977  Go to UniProtKB:  P15977

Oligosaccharides

Help

Entity ID: 2
Molecule	Chains	Chain Length	2D Diagram	Glycosylation
alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose	D	2		N/A

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
IOD	G [auth A], H [auth A], I [auth A], L [auth B], M [auth B], N [auth B], P [auth C], Q [auth C]	IODIDE ION I XMBWDFGMSWQBCA-UHFFFAOYSA-M
EDO	E [auth A], F [auth A], J [auth B], K [auth B], O [auth C]	1,2-ETHANEDIOL C2 H6 O2 LYCAIKOWRPUZTN-UHFFFAOYSA-N

Biologically Interesting Molecules (External Reference) 1 Unique

Entity ID: 2
ID	Chains	Name	Type/Class	2D Diagram	3D Interactions
PRD_900001	D	alpha-maltose	Oligosaccharide /  Nutrient		--

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 = 75.132	α = 76.11
b = 77.019	β = 75.48
c = 128.403	γ = 66.31

Software Package:

Software Name	Purpose
XSCALE	data scaling
REFMAC	refinement
PDB_EXTRACT	data extraction
MAR345	data collection
XDS	data reduction
PHASER	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2015-03-26 
• Released Date: 2015-07-08 
Deposition Author(s): Weiss, S.C., Schiefner, A.

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
• 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