title: The Bacterial Sec Pathway of Protein Export: Screening and Follow-Up.
abstract: Most noncytoplasmic bacterial proteins are exported through the SecYEG channel in the cytoplasmic membrane. This channel and its associated proteins, collectively referred to as the Sec pathway, have strong appeal as a possible antibiotic drug target, yet progress toward new drugs targeting this pathway has been slow, perhaps due partly to many researchers' focus on a single component, the SecA ATPase. Here we report on a pathway-based screen in which beta-galactosidase (β-gal) activity is trapped in the cytoplasm of Escherichia coli cells if translocation through SecYEG is impaired. Several hit compounds passed a counterscreen distinguishing between β-gal overexpression and impaired β-gal export. However, the most extensively characterized hit gave limited E. coli growth inhibition (EC(50) ≥ 400 µM), and growth inhibition could not be unambiguously linked to the compound's effect on the Sec pathway. Our study and others underscore the challenges of finding potent druglike hits against this otherwise promising drug target.
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA crowther@uw.edu.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Crowther
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Weller
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Jackson C
authors.initials: JC
authors.lastname: Jones
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Weaver
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, WA, USA.
authors.forename: Erkang
authors.initials: E
authors.lastname: Fan
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Wesley C
authors.initials: WC
authors.lastname: Van Voorhis
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Rosen
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D004305:Dose-Response Relationship, Drug; D055808:Drug Discovery / Q000379:methods; D015870:Gene Expression / Q000187:drug effects; D057166:High-Throughput Screening Assays; D021381:Protein Transport / Q000187:drug effects; D054852:Small Molecule Libraries; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D054852:Small Molecule Libraries; D001616:beta-Galactosidase
keywords: SecE; SecG; SecY; drug development; protein translocation; translocase