title: Elucidation of the Mode of Action of a New Antibacterial Compound Active against Staphylococcus aureus and Pseudomonas aeruginosa.
abstract: Nosocomial and community-acquired infections caused by multidrug resistant bacteria represent a major human health problem. Thus, there is an urgent need for the development of antibiotics with new modes of action. In this study, we investigated the antibacterial characteristics and mode of action of a new antimicrobial compound, SPI031 (N-alkylated 3, 6-dihalogenocarbazol 1-(sec-butylamino)-3-(3,6-dichloro-9H-carbazol-9-yl)propan-2-ol), which was previously identified in our group. This compound exhibits broad-spectrum antibacterial activity, including activity against the human pathogens Staphylococcus aureus and Pseudomonas aeruginosa. We found that SPI031 has rapid bactericidal activity (7-log reduction within 30 min at 4x MIC) and that the frequency of resistance development against SPI031 is low. To elucidate the mode of action of SPI031, we performed a macromolecular synthesis assay, which showed that SPI031 causes non-specific inhibition of macromolecular biosynthesis pathways. Liposome leakage and membrane permeability studies revealed that SPI031 rapidly exerts membrane damage, which is likely the primary cause of its antibacterial activity. These findings were supported by a mutational analysis of SPI031-resistant mutants, a transcriptome analysis and the identification of transposon mutants with altered sensitivity to the compound. In conclusion, our results show that SPI031 exerts its antimicrobial activity by causing membrane damage, making it an interesting starting point for the development of new antibacterial therapies.
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Evelien
authors.initials: E
authors.lastname: Gerits
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Eline
authors.initials: E
authors.lastname: Blommaert
authors.affiliation: School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom.
authors.forename: Anna
authors.initials: A
authors.lastname: Lippell
authors.affiliation: School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: O'Neill
authors.affiliation: Department of Information Technology (INTEC, iMINDS), U.Ghent, Ghent, Belgium.
authors.forename: Bram
authors.initials: B
authors.lastname: Weytjens
authors.affiliation: Department of Information Technology (INTEC, iMINDS), U.Ghent, Ghent, Belgium.
authors.forename: Dries
authors.initials: D
authors.lastname: De Maeyer
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.|Department of Information Technology (INTEC, iMINDS), U.Ghent, Ghent, Belgium.
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Fierro
authors.affiliation: Department of Information Technology (INTEC, iMINDS), U.Ghent, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, U.Ghent, Ghent, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Marchal
authors.affiliation: CISTIM Leuven vzw, Bio-Incubator, KU Leuven, Leuven, Belgium.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Marchand
authors.affiliation: CISTIM Leuven vzw, Bio-Incubator, KU Leuven, Leuven, Belgium.|Centre for Drug Design and Discovery (CD3), Research and Development, KU Leuven, Leuven, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Chaltin
authors.affiliation: Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Spincemaille
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Katrijn
authors.initials: K
authors.lastname: De Brucker
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Karin
authors.initials: K
authors.lastname: Thevissen
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.|Department of Plant Systems Biology, VIB, Ghent, Belgium.
authors.forename: Bruno P A
authors.initials: BP
authors.lastname: Cammue
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Toon
authors.initials: T
authors.lastname: Swings
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Veerle
authors.initials: V
authors.lastname: Liebens
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.|imec, Smart Systems and Emerging Technologies Unit, Department of Life Science Technologies, Leuven, Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Fauvart
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Natalie
authors.initials: N
authors.lastname: Verstraeten
authors.affiliation: Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Michiels
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000187:drug effects; D002227:Carbazoles / Q000737:chemistry / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D005227:Fatty Acids / Q000096:biosynthesis; D020869:Gene Expression Profiling; D053263:Gene Regulatory Networks / Q000187:drug effects; D005798:Genes, Bacterial; D007700:Kinetics; D050356:Lipid Metabolism / Q000187:drug effects / Q000235:genetics; D008081:Liposomes / Q000737:chemistry; D046911:Macromolecular Substances / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D010743:Phospholipids / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002227:Carbazoles; D005227:Fatty Acids; D008081:Liposomes; D046911:Macromolecular Substances; D010743:Phospholipids