3TON

Crystral Structure of the C-terminal Subunit of Human Maltase-Glucoamylase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.95 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.232 
  • R-Value Observed: 0.235 

wwPDB Validation   3D Report Full Report


This is version 1.0 of the entry. See complete history


Literature

Structural insight into substrate specificity of human intestinal maltase-glucoamylase

Ren, L.M.Qin, X.H.Cao, X.F.Wang, L.L.Bai, F.Bai, G.Shen, Y.

(2011) Protein Cell 2: 827-836

  • DOI: https://doi.org/10.1007/s13238-011-1105-3
  • Primary Citation of Related Structures:  
    3TON, 3TOP

  • PubMed Abstract: 
  • Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities ...

    Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities. In this study, we report crystal structures of MGAM-C alone at a resolution of 3.1 Å, and in complex with its inhibitor acarbose at a resolution of 2.9 Å. Structural studies, combined with biochemical analysis, revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites (+ 2 and + 3 subsites), accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N. Moreover, we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides. These results provide important information for understanding the substrate specificity of alpha-glucosidases during the process of terminal starch digestion, and for designing more efficient drugs to control type 2 diabetes or obesity.


    Organizational Affiliation

    State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Maltase-glucoamylase, intestinalA, B908Homo sapiensMutation(s): 0 
Gene Names: MGAMMGAMGAML
EC: 3.2.1.20 (PDB Primary Data), 3.2.1.3 (PDB Primary Data)
UniProt & NIH Common Fund Data Resources
Find proteins for O43451 (Homo sapiens)
Explore O43451 
Go to UniProtKB:  O43451
PHAROS:  O43451
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO43451
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.95 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.232 
  • R-Value Observed: 0.235 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 106.232α = 90
b = 106.232β = 90
c = 517.557γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
PHASESphasing
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-11-23
    Type: Initial release