title: Allicin Induces Thiol Stress in Bacteria through S-Allylmercapto Modification of Protein Cysteines.
abstract: Allicin (diallyl thiosulfinate) from garlic is a highly potent natural antimicrobial substance. It inhibits growth of a variety of microorganisms, among them antibiotic-resistant strains. However, the precise mode of action of allicin is unknown. Here, we show that growth inhibition of Escherichia coli during allicin exposure coincides with a depletion of the glutathione pool and S-allylmercapto modification of proteins, resulting in overall decreased total sulfhydryl levels. This is accompanied by the induction of the oxidative and heat stress response. We identified and quantified the allicin-induced modification S-allylmercaptocysteine for a set of cytoplasmic proteins by using a combination of label-free mass spectrometry and differential isotope-coded affinity tag labeling of reduced and oxidized thiol residues. Activity of isocitrate lyase AceA, an S-allylmercapto-modified candidate protein, is largely inhibited by allicin treatment in vivo Allicin-induced protein modifications trigger protein aggregation, which largely stabilizes RpoH and thereby induces the heat stress response. At sublethal concentrations, the heat stress response is crucial to overcome allicin stress. Our results indicate that the mode of action of allicin is a combination of a decrease of glutathione levels, unfolding stress, and inactivation of crucial metabolic enzymes through S-allylmercapto modification of cysteines.
authors.affiliation: From the Institute of Biochemistry and Pathobiochemistry-Microbial Biochemistry.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Müller
authors.affiliation: From the Institute of Biochemistry and Pathobiochemistry-Microbial Biochemistry.
authors.forename: Jakob
authors.initials: J
authors.lastname: Eller
authors.affiliation: Department of Plant Physiology, Rheinisch-Westfälische Technische Hochschule Aachen University, 52056 Aachen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Albrecht
authors.affiliation: Angewandte Mikrobiologie, and.
authors.forename: Pascal
authors.initials: P
authors.lastname: Prochnow
authors.affiliation: Medizinisches Proteom-Center, Ruhr University Bochum, 44780 Bochum, Germany and.
authors.forename: Katja
authors.initials: K
authors.lastname: Kuhlmann
authors.affiliation: Angewandte Mikrobiologie, and.
authors.forename: Julia Elisabeth
authors.initials: JE
authors.lastname: Bandow
authors.affiliation: Department of Plant Physiology, Rheinisch-Westfälische Technische Hochschule Aachen University, 52056 Aachen, Germany.
authors.forename: Alan John
authors.initials: AJ
authors.lastname: Slusarenko
authors.affiliation: From the Institute of Biochemistry and Pathobiochemistry-Microbial Biochemistry, lars.leichert@ruhr-uni-bochum.de.
authors.forename: Lars Ingo Ole
authors.identifier: 0000-0002-5666-9681
authors.initials: LI
authors.lastname: Leichert
mesh_terms: D003545:Cysteine / Q000378:metabolism; D004220:Disulfides; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005737:Garlic / Q000737:chemistry; D005978:Glutathione / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D013441:Sulfinic Acids / Q000494:pharmacology*
chemical_list: D004220:Disulfides; D029968:Escherichia coli Proteins; D010936:Plant Extracts; D013438:Sulfhydryl Compounds; D013441:Sulfinic Acids; C006452:allicin; D005978:Glutathione; D003545:Cysteine
keywords: Escherichia coli (E. coli); S-allylmercapto modification; allicin; antibiotic action; bacteria; disulfide; garlic (Allium sativum); redox proteomics; thiol