The Crystal Structure of 1D-myo-inositol 2-acetamido-2-deoxy-alpha-D-glucopyranoside Deacetylase (MshB)

Experimental Data Snapshot

  • Resolution: 1.70 Å
  • R-Value Free: 0.228 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.196 

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The Crystal Structure of 1-D-myo-Inositol 2-Acetamido-2-deoxy-alpha-D-glucopyranoside Deacetylase (MshB) from Mycobacterium tuberculosis Reveals a Zinc Hydrolase with a Lactate Dehydrogenase Fold.

Maynes, J.T.Garen, C.Cherney, M.M.Newton, G.Arad, D.Av-Gay, Y.Fahey, R.C.James, M.N.

(2003) J Biol Chem 278: 47166-47170

  • DOI: https://doi.org/10.1074/jbc.M308914200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Mycothiol (1-D-myo-inosityl 2-(N-acetyl-L-cysteinyl)amido-2-deoxy-alpha-D-glucopyranoside, MSH or AcCys-GlcN-inositol (Ins)) is the major reducing agent in actinomycetes, including Mycobacterium tuberculosis. The biosynthesis of MSH involves a deacetylase that removes the acetyl group from the precursor GlcNAc-Ins to yield GlcN-Ins. The deacetylase (MshB) corresponds to Rv1170 of M. tuberculosis with a molecular mass of 33,400 Da. MshB is a Zn2+ metalloprotein, and the deacetylase activity is completely dependent on the presence of a divalent metal cation. We have determined the x-ray crystallographic structure of MshB, which reveals a protein that folds in a manner resembling lactate dehydrogenase in the N-terminal domain and a C-terminal domain consisting of two beta-sheets and two alpha-helices. The zinc binding site is in the N-terminal domain occupying a position equivalent to that of the NAD+ co-factor of lactate dehydrogenase. The Zn2+ is 5 coordinate with 3 residues from MshB (His-13, Asp-16, His-147) and two water molecules. One water would be displaced upon binding of substrate (GlcNAc-Ins); the other is proposed as the nucleophilic water assisted by the general base carboxylate of Asp-15. In addition to the Zn2+ providing electrophilic assistance in the hydrolysis, His-144 imidazole could form a hydrogen bond to the oxyanion of the tetrahedral intermediate. The extensive sequence identity of MshB, the deacetylase, with mycothiol S-conjugate amidase, an amide hydrolase that mediates detoxification of mycothiol S-conjugate xenobiotics, has allowed us to construct a faithful model of the catalytic domain of mycothiol S-conjugate amidase based on the structure of MshB.

  • Organizational Affiliation

    Canadian Institutes of Health Research, Group in Protein Structure and Function, Department of Biochemistry, Faculty of Medicine, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
1D-myo-inositol 2-acetamido-2-deoxy-alpha-D-glucopyranoside Deacetylase (MshB)
A, B, C, D
303Mycobacterium tuberculosisMutation(s): 0 
Gene Names: Rv1170
Find proteins for P9WJN3 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Explore P9WJN3 
Go to UniProtKB:  P9WJN3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP9WJN3
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.70 Å
  • R-Value Free: 0.228 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.196 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 56.794α = 102.09
b = 73.964β = 108.16
c = 85.587γ = 97.18
Software Package:
Software NamePurpose
MOSFLMdata reduction
CCP4data scaling

Structure Validation

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Entry History 

Revision History  (Full details and data files)

  • Version 1.0: 2003-12-02
    Type: Initial release
  • Version 1.1: 2007-10-16
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-21
    Changes: Data collection, Database references, Derived calculations