title: Discovery of antibacterial cyclic peptides that inhibit the ClpXP protease.
abstract: A method to rapidly screen libraries of cyclic peptides in vivo for molecules with biological activity has been developed and used to isolate cyclic peptide inhibitors of the ClpXP protease. Fluorescence activated cell sorting was used in conjunction with a fluorescent reporter to isolate cyclic peptides that inhibit the proteolysis of tmRNA-tagged proteins in Escherichia coli. Inhibitors shared little sequence similarity and interfered with unexpected steps in the ClpXP mechanism in vitro. One cyclic peptide, IXP1, inhibited the degradation of unrelated ClpXP substrates and has bactericidal activity when added to growing cultures of Caulobacter crescentus, a model organism that requires ClpXP activity for viability. The screen used here could be adapted to identify cyclic peptide inhibitors of any enzyme that can be expressed in E. coli in conjunction with a fluorescent reporter.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Cheng
authors.forename: Todd A
authors.initials: TA
authors.lastname: Naumann
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Horswill
authors.forename: Sue-Jean
authors.initials: SJ
authors.lastname: Hong
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: Venters
authors.forename: John W
authors.initials: JW
authors.lastname: Tomsho
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Benkovic
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Keiler
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors*; D016935:Caulobacter crescentus / Q000201:enzymology; D049071:Endopeptidase Clp / Q000037:antagonists & inhibitors*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D019151:Peptide Library; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D013379:Substrate Specificity
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008164:Luminescent Proteins; D019151:Peptide Library; D010456:Peptides, Cyclic; D011480:Protease Inhibitors; D049071:Endopeptidase Clp