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Abstract

We describe de novo-designed α-helical barrels (αHBs) that bind and discriminate between lipophilic biologically active molecules. αHBs have five or more α-helices arranged around central hydrophobic channels the diameters of which scale with oligomer state. We show that pentameric, hexameric, and heptameric αHBs bind the environmentally sensitive dye 1,6-diphenylhexatriene (DPH) in the micromolar range and fluoresce. Displacement of the dye is used to report the binding of nonfluorescent molecules: palmitic acid and retinol bind to all three αHBs with submicromolar inhibitor constants; farnesol binds the hexamer and heptamer; but β-carotene binds only the heptamer. A co-crystal structure of the hexamer with farnesol reveals oriented binding in the center of the hydrophobic channel. Charged side chains engineered into the lumen of the heptamer facilitate binding of polar ligands: a glutamate variant binds a cationic variant of DPH, and introducing lysine allows binding of the biosynthetically important farnesol diphosphate.

Original languageEnglish
Pages (from-to)1808-1816
Number of pages9
JournalACS Synthetic Biology
Volume7
Issue number7
Early online date30 Jun 2018
DOIs
Publication statusPublished - 20 Jul 2018

Structured keywords

  • BrisSynBio
  • Bristol BioDesign Institute
  • BCS and TECS CDTs

Keywords

  • coiled coil
  • molecular dynamics
  • rational peptide design
  • small-molecule binding
  • α-helical barrel
  • Synthetic biology

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