title: Role for dithiolopyrrolones in disrupting bacterial metal homeostasis.
abstract: Natural products harbor unique and complex structures that provide valuable antibiotic scaffolds. With an increase in antibiotic resistance, natural products once again hold promise for new antimicrobial therapies, especially those with unique scaffolds that have been overlooked due to a lack of understanding of how they function. Dithiolopyrrolones (DTPs) are an underexplored class of disulfide-containing natural products, which exhibit potent antimicrobial activities against multidrug-resistant pathogens. DTPs were thought to target RNA polymerase, but conflicting observations leave the mechanisms elusive. Using a chemical genomics screen inEscherichia coli, we uncover a mode of action for DTPs-the disruption of metal homeostasis. We show that holomycin, a prototypical DTP, is reductively activated, and reduced holomycin chelates zinc with high affinity. Examination of reduced holomycin against zinc-dependent metalloenzymes revealed that it inhibitsE. coliclass II fructose bisphosphate aldolase, but not RNA polymerase. Reduced holomycin also strongly inhibits metallo-β-lactamases in vitro, major contributors to clinical carbapenem resistance, by removing active site zinc. These results indicate that holomycin is an intracellular metal-chelating antibiotic that inhibits a subset of metalloenzymes and that RNA polymerase is unlikely to be the primary target. Our work establishes a link between the chemical structures of DTPs and their antimicrobial action; the ene-dithiol group of DTPs enables high-affinity metal binding as a central mechanism to inhibit metabolic processes. Our study also validates the use of chemical genomics in characterizing modes of actions of antibiotics and emphasizes the potential of metal-chelating natural products in antimicrobial therapy.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Chan
authors.affiliation: Graduate Group in Biophysics, University of California, San Francisco, CA 94143.
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Shiver
authors.affiliation: Department of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Wever
authors.affiliation: Department of Chemistry, Duke University, NC 27708.
authors.forename: Sayyeda Zeenat A
authors.initials: SZ
authors.lastname: Razvi
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Traxler
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599; boli@email.unc.edu.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000627:therapeutic use; D001688:Biological Products / Q000737:chemistry / Q000627:therapeutic use; D020134:Catalytic Domain / Q000187:drug effects; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors / Q000235:genetics; D004220:Disulfides / Q000737:chemistry / Q000627:therapeutic use; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D023281:Genomics; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D007769:Lactams / Q000737:chemistry / Q000494:pharmacology*; D008667:Metalloproteins / Q000037:antagonists & inhibitors / Q000235:genetics; D008670:Metals / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry* / Q000627:therapeutic use; D014050:Toluene / Q000031:analogs & derivatives* / Q000737:chemistry / Q000627:therapeutic use; D015032:Zinc / Q000378:metabolism; D001618:beta-Lactamases / Q000187:drug effects / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001688:Biological Products; D004220:Disulfides; D007769:Lactams; D008667:Metalloproteins; D008670:Metals; D011758:Pyrroles; D014050:Toluene; C015265:holomycin; D012321:DNA-Directed RNA Polymerases; D001618:beta-Lactamases; D015032:Zinc; C004848:dithiol
keywords: antibiotics; metallophore; mode of action; natural products; zinc chelation