1NMM

beta-1,4-galactosyltransferase mutant Cys342Thr complex with alpha-lactalbumin and GlcNAc


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.189 
  • R-Value Observed: 0.189 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

alpha-Lactalbumin (LA) stimulates milk beta-1,4-galactosyltransferase I (beta 4Gal-T1) to transfer glucose from UDP-glucose to N-acetylglucosamine. Crystal structure of beta 4Gal-T1 x LA complex with UDP-Glc.

Ramakrishnan, B.Shah, P.S.Qasba, P.K.

(2001) J Biol Chem 276: 37665-37671

  • DOI: 10.1074/jbc.M102458200
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • beta-1,4-Galactosyltransferase 1 (Gal-T1) transfers galactose (Gal) from UDP-Gal to N-acetylglucosamine (GlcNAc), which constitutes its normal galactosyltransferase (Gal-T) activity. In the presence of alpha-lactalbumin (LA), it transfers Gal to Glc, ...

    beta-1,4-Galactosyltransferase 1 (Gal-T1) transfers galactose (Gal) from UDP-Gal to N-acetylglucosamine (GlcNAc), which constitutes its normal galactosyltransferase (Gal-T) activity. In the presence of alpha-lactalbumin (LA), it transfers Gal to Glc, which is its lactose synthase (LS) activity. It also transfers glucose (Glc) from UDP-Glc to GlcNAc, constituting the glucosyltransferase (Glc-T) activity, albeit at an efficiency of only 0.3-0.4% of Gal-T activity. In the present study, we show that LA increases this activity almost 30-fold. It also enhances the Glc-T activity toward various N-acyl substituted glucosamine acceptors. Steady state kinetic studies of Glc-T reaction show that the K(m) for the donor and acceptor substrates are high in the absence of LA. In the presence of LA, the K(m) for the acceptor substrate is reduced 30-fold, whereas for UDP-Glc it is reduced only 5-fold. In order to understand this property, we have determined the crystal structures of the Gal-T1.LA complex with UDP-Glc x Mn(2+) and with N-butanoyl-glucosamine (N-butanoyl-GlcN), a preferred sugar acceptor in the Glc-T activity. The crystal structures reveal that although the binding of UDP-Glc is quite similar to UDP-Gal, there are few significant differences observed in the hydrogen bonding interactions between UDP-Glc and Gal-T1. Based on the present kinetic and crystal structural studies, a possible explanation for the role of LA in the Glc-T activity has been proposed.


    Organizational Affiliation

    Structural Glycobiology Section, Laboratory of Experimental and Computational Biology, Center for Cancer Research, NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702, USA.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ALPHA-LACTALBUMINA, C123Mus musculusMutation(s): 0 
Gene Names: Lalba
Find proteins for P29752 (Mus musculus)
Explore P29752 
Go to UniProtKB:  P29752
Protein Feature View
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  • Reference Sequence

Find similar proteins by: Sequence  |  Structure

Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
BETA-1,4-GALACTOSYLTRANSFERASEB, D286Bos taurusMutation(s): 1 
Gene Names: B4GALT1GALTGGTB2
EC: 2.4.1.22 (PDB Primary Data), 2.4.1.90 (PDB Primary Data), 2.4.1.38 (PDB Primary Data), 2.4.1 (UniProt), 2.4.1.275 (UniProt)
Find proteins for P08037 (Bos taurus)
Explore P08037 
Go to UniProtKB:  P08037
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NAG
Query on NAG

Download CCD File 
B, D
2-acetamido-2-deoxy-beta-D-glucopyranose
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
PG4
Query on PG4

Download CCD File 
D
TETRAETHYLENE GLYCOL
C8 H18 O5
UWHCKJMYHZGTIT-UHFFFAOYSA-N
 Ligand Interaction
CA
Query on CA

Download CCD File 
A, C
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.189 
  • R-Value Observed: 0.189 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 57.019α = 90
b = 95.626β = 101.37
c = 100.213γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
AMoREphasing
CNSrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-01-21
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 1.3: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Derived calculations, Structure summary