title: Small-molecule inhibitors of gram-negative lipoprotein trafficking discovered by phenotypic screening.
abstract: In Gram-negative bacteria, lipoproteins are transported to the outer membrane by the Lol system. In this process, lipoproteins are released from the inner membrane by the ABC transporter LolCDE and passed to LolA, a diffusible periplasmic molecular chaperone. Lipoproteins are then transferred to the outer membrane receptor protein, LolB, for insertion in the outer membrane. Here we describe the discovery and characterization of novel pyridineimidazole compounds that inhibit this process. Escherichia coli mutants resistant to the pyridineimidazoles show no cross-resistance to other classes of antibiotics and map to either the LolC or LolE protein of the LolCDE transporter complex. The pyridineimidazoles were shown to inhibit the LolA-dependent release of the lipoprotein Lpp from E. coli spheroplasts. These results combined with bacterial cytological profiling are consistent with LolCDE-mediated disruption of lipoprotein targeting to the outer membrane as the mode of action of these pyridineimidazoles. The pyridineimidazoles are the first reported inhibitors of the LolCDE complex, a target which has never been exploited for therapeutic intervention. These compounds open the door to further interrogation of the outer membrane lipoprotein transport pathway as a target for antimicrobial therapy.
authors.affiliation: Department of Bioscience, Infection Innovative Medicines Unit, AstraZeneca R&D Boston, Waltham, Massachusetts, USA sarah.mcleod@astrazeneca.com.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: McLeod
authors.affiliation: Department of Chemistry, Infection Innovative Medicines Unit, AstraZeneca R&D Boston, Waltham, Massachusetts, USA.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Fleming
authors.affiliation: Department of Bioscience, Infection Innovative Medicines Unit, AstraZeneca R&D Boston, Waltham, Massachusetts, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: MacCormack
authors.affiliation: Department of Bioscience, Infection Innovative Medicines Unit, AstraZeneca R&D Boston, Waltham, Massachusetts, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: McLaughlin
authors.affiliation: Department of Bioscience, Infection Innovative Medicines Unit, AstraZeneca R&D Boston, Waltham, Massachusetts, USA.
authors.forename: James D
authors.initials: JD
authors.lastname: Whiteaker
authors.affiliation: University of Morioka, Takizawa, Iwate, Japan.
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Narita
authors.affiliation: University of Morioka, Takizawa, Iwate, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Mori
authors.affiliation: University of Morioka, Takizawa, Iwate, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Tokuda
authors.affiliation: Department of Bioscience, Infection Innovative Medicines Unit, AstraZeneca R&D Boston, Waltham, Massachusetts, USA.
authors.forename: Alita A
authors.initials: AA
authors.lastname: Miller
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D007093:Imidazoles / Q000737:chemistry / Q000494:pharmacology*; D008074:Lipoproteins / Q000378:metabolism*; D015394:Molecular Structure; D009154:Mutation; D010641:Phenotype; D021381:Protein Transport / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D007093:Imidazoles; D008074:Lipoproteins