2AHB

X-ray crystal structure of R46A,R161A mutant of Mycobacterium tuberculosis FabH


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.218 

wwPDB Validation   3D Report Full Report


This is version 1.6 of the entry. See complete history


Literature

Probing the Mechanism of the Mycobacterium tuberculosis {beta}-Ketoacyl-Acyl Carrier Protein Synthase III mtFabH: FACTORS INFLUENCING CATALYSIS AND SUBSTRATE SPECIFICITY

Brown, A.K.Sridharan, S.Kremer, L.Lindenberg, S.Dover, L.G.Sacchettini, J.C.Besra, G.S.

(2005) J Biol Chem 280: 32539-32547

  • DOI: https://doi.org/10.1074/jbc.M413216200
  • Primary Citation of Related Structures:  
    1M1M, 2AHB, 2AJ9

  • PubMed Abstract: 

    Mycolic acids are the dominant feature of the Mycobacterium tuberculosis cell wall. These alpha-alkyl, beta-hydroxy fatty acids are formed by the condensation of two fatty acids, a long meromycolic acid and a shorter C(24)-C(26) fatty acid. The component fatty acids are produced via a combination of type I and II fatty acid synthases (FAS) with FAS-I products being elongated by FAS-II toward meromycolic acids. The beta-ketoacyl-acyl carrier protein (ACP) synthase III encoded by mtfabH (mtFabH) links FAS-I and FAS-II, catalyzing the condensation of FAS-I-derived acyl-CoAs with malonyl-acyl carrier protein (ACP). The acyl-CoA chain length specificity of mtFabH was assessed in vitro; the enzyme extended longer, physiologically relevant acyl-CoA primers when paired with AcpM, its natural partner, than with Escherichia coli ACP. The ability of the enzyme to use E. coli ACP suggests that a similar mode of binding is likely with both ACPs, yet it is clear that unique factors inherent to AcpM modulate the substrate specificity of mtFabH. Mutation of proposed key mtFabH residues was used to define their catalytic roles. Substitution of supposed acyl-CoA binding residues reduced transacylation, with double substitutions totally abrogating activity. Mutation of Arg(46) revealed its more critical role in malonyl-AcpM decarboxylation than in the acyl-CoA binding role. Interestingly, this effect was suppressed intragenically by Arg(161) --> Ala substitution. Our structural studies suggested that His(258), previously implicated in malonyl-ACP decarboxylation, also acts as an anchor point for a network of water molecules that we propose promotes deprotonation and transacylation of Cys(122).


  • Organizational Affiliation

    School of Cellular and Molecular Biosciences, University of Newcastle upon Tyne, UK.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Beta- ketoacyl-ACP synthase III
A, B
356Mycobacterium tuberculosisMutation(s): 2 
Gene Names: fabH
EC: 2.3.1.41
UniProt
Find proteins for P9WNG3 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Explore P9WNG3 
Go to UniProtKB:  P9WNG3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP9WNG3
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.218 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 103.445α = 90
b = 81.412β = 106.91
c = 97.281γ = 90
Software Package:
Software NamePurpose
ADVXdata collection
SCALEPACKdata scaling
MOLREPphasing
CNSrefinement
Adxvdata processing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-08-23
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2011-11-16
    Changes: Atomic model
  • Version 1.4: 2017-10-11
    Changes: Data collection, Refinement description
  • Version 1.5: 2021-10-20
    Changes: Database references
  • Version 1.6: 2023-08-23
    Changes: Data collection, Refinement description