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Updated: Jul 3, 2026
11:01
Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase
Published on: November 23, 2016
Arylamine N-acetyltransferases in mycobacteria
Edith Sim1, James Sandy, Dimitrios Evangelopoulos
1Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX13QT, UK. edith.sim@pharm.ox.ac.uk
Current Drug Metabolism
|August 6, 2008
Summary
Mycobacterial N-acetyltransferase (NAT) enzymes, homologous to human NAT2, are crucial for isoniazid inactivation and survival within macrophages. Their structures suggest roles in cell wall lipid synthesis and amide bond formation.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Human arylamine N-acetyltransferase 2 (NAT2) inactivates isoniazid, an anti-tubercular drug, via acetyltransfer from acetyl-CoA.
- Homologous NAT proteins are present in various mycobacteria, including Mycobacterium tuberculosis, M. bovis BCG, M. smegmatis, and M. marinum.
- Previous crystallographic studies revealed the structure of Salmonella typhimurium NAT.
Purpose of the Study:
- To elucidate the structural basis of mycobacterial NAT function.
- To compare the structure and CoA binding of M. marinum NAT with human NAT2.
- To explore the potential roles of mycobacterial NAT in cell wall lipid synthesis and survival.
Main Methods:
- X-ray crystallography was used to determine the structures of M. marinum and M. smegmatis NATs.
- Structures were analyzed in both native forms and complexed with isoniazid.
- Comparison of mycobacterial NAT structures with human NAT2 and Salmonella typhimurium NAT.
Main Results:
- Mycobacterial NATs share a similar fold with three domains and a catalytic triad (cysteine, histidine, aspartate).
- M. marinum NAT exhibits a more open CoA binding mode compared to human NAT2.
- Gene deletion studies suggest NAT protein's essential role in M. bovis BCG survival within macrophages, linked to cholesterol degradation (hsaA-D) and stress response genes.
- Homology to streptomyces amide synthases suggests a role in intramolecular amide bond formation.
Conclusions:
- Mycobacterial NAT structures provide insights into their catalytic mechanisms and potential roles beyond drug inactivation.
- The distinct CoA binding mode of M. marinum NAT may relate to its proposed function in cell wall lipid synthesis.
- NAT's coordinated expression with cholesterol degradation genes highlights its importance for mycobacterial survival in host macrophages.
- Structural differences suggest mycobacterial amide synthases may not utilize soluble CoA intermediates in their reaction mechanisms.
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