title: Piperidinols that show anti-tubercular activity as inhibitors of arylamine N-acetyltransferase: an essential enzyme for mycobacterial survival inside macrophages.
abstract: Latent M. tuberculosis infection presents one of the major obstacles in the global eradication of tuberculosis (TB). Cholesterol plays a critical role in the persistence of M. tuberculosis within the macrophage during latent infection. Catabolism of cholesterol contributes to the pool of propionyl-CoA, a precursor that is incorporated into cell-wall lipids. Arylamine N-acetyltransferase (NAT) is encoded within a gene cluster that is involved in the cholesterol sterol-ring degradation and is essential for intracellular survival. The ability of the NAT from M. tuberculosis (TBNAT) to utilise propionyl-CoA links it to the cholesterol-catabolism pathway. Deleting the nat gene or inhibiting the NAT enzyme prevents intracellular survival and results in depletion of cell-wall lipids. TBNAT has been investigated as a potential target for TB therapies. From a previous high-throughput screen, 3-benzoyl-4-phenyl-1-methylpiperidinol was identified as a selective inhibitor of prokaryotic NAT that exhibited antimycobacterial activity. The compound resulted in time-dependent irreversible inhibition of the NAT activity when tested against NAT from M. marinum (MMNAT). To further evaluate the antimycobacterial activity and the NAT inhibition of this compound, four piperidinol analogues were tested. All five compounds exert potent antimycobacterial activity against M. tuberculosis with MIC values of 2.3-16.9 µM. Treatment of the MMNAT enzyme with this set of inhibitors resulted in an irreversible time-dependent inhibition of NAT activity. Here we investigate the mechanism of NAT inhibition by studying protein-ligand interactions using mass spectrometry in combination with enzyme analysis and structure determination. We propose a covalent mechanism of NAT inhibition that involves the formation of a reactive intermediate and selective cysteine residue modification. These piperidinols present a unique class of antimycobacterial compounds that have a novel mode of action different from known anti-tubercular drugs.
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, United Kingdom.
authors.forename: Areej
authors.initials: A
authors.lastname: Abuhammad
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Fullam
authors.forename: Edward D
authors.initials: ED
authors.lastname: Lowe
authors.forename: David
authors.initials: D
authors.lastname: Staunton
authors.forename: Akane
authors.initials: A
authors.lastname: Kawamura
authors.forename: Isaac M
authors.initials: IM
authors.lastname: Westwood
authors.forename: Sanjib
authors.initials: S
authors.lastname: Bhakta
authors.forename: Alun Christopher
authors.initials: AC
authors.lastname: Garner
authors.forename: David L
authors.initials: DL
authors.lastname: Wilson
authors.forename: Peter T
authors.initials: PT
authors.lastname: Seden
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Davies
authors.forename: Angela J
authors.initials: AJ
authors.lastname: Russell
authors.forename: Elspeth F
authors.initials: EF
authors.lastname: Garman
authors.forename: Edith
authors.initials: E
authors.lastname: Sim
mesh_terms: D000818:Animals; D000995:Antitubercular Agents / Q000737:chemistry / Q000494:pharmacology*; D001191:Arylamine N-Acetyltransferase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D062105:Molecular Docking Simulation; D009161:Mycobacterium / Q000187:drug effects* / Q000201:enzymology*; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology*; D011487:Protein Conformation
chemical_list: D000995:Antitubercular Agents; D004791:Enzyme Inhibitors; D010880:Piperidines; D001191:Arylamine N-Acetyltransferase