2QC3

Crystal structure of MCAT from Mycobacterium tuberculosis


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.198 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

The Crystal Structure of MCAT from Mycobacterium tuberculosis Reveals Three New Catalytic Models.

Li, Z.Huang, Y.Ge, J.Fan, H.Zhou, X.Li, S.Bartlam, M.Wang, H.Rao, Z.

(2007) J.Mol.Biol. 371: 1075-1083

  • DOI: 10.1016/j.jmb.2007.06.004

  • PubMed Abstract: 
  • The malonyl coenzyme A (CoA)-acyl carrier protein (ACP) transacylase (MCAT) plays a key role in cell wall biosynthesis in Mycobacterium tuberculosis and other bacteria. The M. tuberculosis MCAT (MtMCAT) is encoded by the FabD gene and catalyzes the t ...

    The malonyl coenzyme A (CoA)-acyl carrier protein (ACP) transacylase (MCAT) plays a key role in cell wall biosynthesis in Mycobacterium tuberculosis and other bacteria. The M. tuberculosis MCAT (MtMCAT) is encoded by the FabD gene and catalyzes the transacylation of malonate from malonyl-CoA to holo-ACP. Malonyl-ACP is the substrate in fatty acid biosynthesis and is a by-product of the transacylation reaction. This ability for fatty acid biosynthesis enables M. tuberculosis to survive in hostile environments, and thus understanding the mechanism of biosynthesis is important for the design of new anti-tuberculosis drugs. The 2.3 A crystal structure of MtMCAT reported here shows that its catalytic mechanism differs from those of ScMCAT and EcMCAT, whose structures have previously been determined. In MtMCAT, the C(beta)-O(gamma) bond of Ser91 turns upwards, resulting in a different orientation and thus an overall change of the active pocket compared to other known MCAT enzymes. We identify three new nucleophilic attack chains from the MtMCAT structure: His90-Ser91, Asn155-Wat6-Ser91 and Asn155-His90-Ser91. Enzyme activity assays show that His90A, Asn155A and His90A-Asn155A mutants all have substantially reduced MCAT activity, indicating that M. tuberculosis MCAT supports a unique means of proton transfer. Furthermore, His194 cannot form part of a His-Ser catalytic dyad and only stabilizes the substrate. This new discovery should provide a deeper insight into the catalytic mechanisms of MCATs.


    Organizational Affiliation

    Tsinghua-Nankai-IBP Joint Research Group for Structural Biology, Tsinghua University, Beijing 100084, China.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Malonyl CoA-acyl carrier protein transacylase
A
303Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv)Mutation(s): 0 
Gene Names: fabD
EC: 2.3.1.39
Find proteins for P9WNG5 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Go to UniProtKB:  P9WNG5
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACY
Query on ACY

Download SDF File 
Download CCD File 
A
ACETIC ACID
C2 H4 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.198 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 36.520α = 90.00
b = 48.171β = 98.89
c = 77.414γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data scaling
CNSphasing
CNSrefinement
HKL-2000data reduction
MAR345dtbdata collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-08-28
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Source and taxonomy, Version format compliance