2BMX

Mycobacterium tuberculosis AhpC

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.195 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history. 

Literature

Structure and Mechanism of the Alkyl Hydroperoxidase Ahpc, a Key Element of the Mycobacterium Tuberculosis Defense System Against Oxidative Stress.

Guimaraes, B.G., Souchon, H., Honore, N., Saint-Joanis, B., Brosch, R., Shepard, W., Cole, S.T., Alzari, P.M.

(2005) J.Biol.Chem. 280: 25735

  • DOI: 10.1074/jbc.M503076200

  • PubMed Abstract: 

    • The peroxiredoxin AhpC from Mycobacterium tuberculosis (MtAhpC) is the foremost element of a NADH-dependent peroxidase and peroxynitrite reductase system, where it directly reduces peroxides and peroxynitrite and is in turn reduced by AhpD and other ...

    The peroxiredoxin AhpC from Mycobacterium tuberculosis (MtAhpC) is the foremost element of a NADH-dependent peroxidase and peroxynitrite reductase system, where it directly reduces peroxides and peroxynitrite and is in turn reduced by AhpD and other proteins. Overexpression of MtAhpC in isoniazid-resistant strains of M. tuberculosis harboring mutations in the catalase/peroxidase katG gene provides antioxidant protection and may substitute for the lost enzyme activities. We report here the crystal structure of oxidized MtAhpC trapped in an intermediate oligomeric state of its catalytic cycle. The overall structure folds into a ring-shaped hexamer of dimers instead of the usual pentamer of dimers observed in other reduced peroxiredoxins. Although the general structure of the functional dimer is similar to that of other 2-Cys peroxiredoxins, the alpha-helix containing the peroxidatic cysteine Cys61 undergoes a unique rigid-body movement to allow the formation of the disulfide bridge with the resolving cysteine Cys174. This conformational rearrangement creates a large internal cavity enclosing the active site, which might be exploited for the design of inhibitors that could block the catalytic cycle. Structural and mutagenesis evidence points to a model for the electron transfer pathway in MtAhpC that accounts for the unusual involvement of three cysteine residues in catalysis and suggests a mechanism by which MtAhpC can specifically interact with different redox partners.

    Organizational Affiliation: 

    Unité de Biochimie Structurale, CNRS URA 2185, 25 rue du Docteur Roux and Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ALKYL HYDROPEROXIDASE C
A, B, C
195Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv)Mutation(s): 1 
Gene Names: ahpC
EC: 1.11.1.15
Find proteins for P9WQB7 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Go to UniProtKB:  P9WQB7
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A, B, C
L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.195 
  • Space Group: P 6 2 2
Unit Cell:
Length (Å)Angle (°)
a = 139.265α = 90.00
b = 139.265β = 90.00
c = 148.525γ = 120.00
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
SHARPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-05-10
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance