title: Discovery of Potent Pantothenamide Inhibitors of Staphylococcus aureus Pantothenate Kinase through a Minimal SAR Study: Inhibition Is Due to Trapping of the Product.
abstract: The potent antistaphylococcal activity of N-substituted pantothenamides (PanAms) has been shown to at least partially be due to the inhibition of Staphylococcus aureus's atypical type II pantothenate kinase (SaPanKII), the first enzyme of coenzyme A biosynthesis. This mechanism of action follows from SaPanKIIhaving a binding mode for PanAms that is distinct from those of other PanKs. To dissect the molecular interactions responsible for PanAm inhibitory activity, we conducted a mini SAR study in tandem with the cocrystallization of SaPanKIIwith two classic PanAms (N5-Pan and N7-Pan), culminating in the synthesis and characterization of two new PanAms, N-Pip-PanAm and MeO-N5-PanAm. The cocrystal structures showed that all of the PanAms are phosphorylated by SaPanKIIbut remain bound at the active site; this occurs primarily through interactions with Tyr240' and Thr172'. Kinetic analysis showed a strong correlation between kcat(slow PanAm turnover) and IC50(inhibition of pantothenate phosphorylation) values, suggesting that SaPanKIIinhibition occurs via a delay in product release. In-depth analysis of the PanAm-bound structures showed that the capacity for accepting a hydrogen bond from the amide of Thr172' was a stronger determinant for PanAm potency than the capacity to π-stack with Tyr240'. The two new PanAms, N-Pip-PanAm and MeO-N5-PanAm, effectively combine both hydrogen bonding and hydrophobic interactions, resulting in the most potent SaPanKIIinhibition described to date. Taken together, our results are consistent with an inhibition mechanism wherein PanAms act as SaPanKIIsubstrates that remain bound upon phosphorylation. The phospho-PanAm-SaPanKIIinteractions described herein may help future antistaphylococcal drug development.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Hughes
authors.affiliation: Department of Biochemistry, Stellenbosch University , Stellenbosch 7600, South Africa.
authors.forename: Leanne
authors.initials: L
authors.lastname: Barnard
authors.forename: Katayoun
authors.initials: K
authors.lastname: Mottaghi
authors.forename: Wolfram
authors.initials: W
authors.lastname: Tempel
authors.affiliation: Department of Biochemistry and Molecular Biology, Tulane School of Medicine , New Orleans, Louisiana 70112, United States.
authors.forename: Tetyana
authors.initials: T
authors.lastname: Antoshchenko
authors.forename: Bum Soo
authors.initials: BS
authors.lastname: Hong
authors.forename: Abdellah
authors.initials: A
authors.lastname: Allali-Hassani
authors.forename: David
authors.initials: D
authors.lastname: Smil
authors.forename: Masoud
authors.initials: M
authors.lastname: Vedadi
authors.affiliation: Department of Biochemistry, Stellenbosch University , Stellenbosch 7600, South Africa.
authors.forename: Erick
authors.initials: E
authors.lastname: Strauss
authors.affiliation: Department of Biochemistry and Molecular Biology, Tulane School of Medicine , New Orleans, Louisiana 70112, United States.
authors.forename: Hee-Won
authors.initials: HW
authors.lastname: Park
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D007700:Kinetics; D008958:Models, Molecular; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D017853:Phosphotransferases (Alcohol Group Acceptor); C023088:pantothenate kinase
keywords: X-ray crystallography; coenzyme A; enzyme inhibition; growth inhibition; pantothenamide; pantothenate kinase