Stabilizing and Understanding a Miniprotein by Rational Redesign

Biochemistry. 2019 Jul 16;58(28):3060-3064. doi: 10.1021/acs.biochem.9b00067. Epub 2019 Jul 8.

Abstract

Miniproteins reduce the complexity of the protein-folding problem allowing systematic studies of contributions to protein folding and stabilization. Here, we describe the rational redesign of a miniprotein, PPα, comprising a polyproline II helix, a loop, and an α helix. The redesign provides a de novo framework for interrogating noncovalent interactions. Optimized PPα has significantly improved thermal stability with a midpoint unfolding temperature (TM) of 51 °C. Its nuclear magnetic resonance structure indicates a density of stabilizing noncovalent interactions that is higher than that of the parent peptide, specifically an increased number of CH-π interactions. In part, we attribute this to improved long-range electrostatic interactions between the two helical elements. We probe further sequence-stability relationships in the miniprotein through a series of rational mutations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Peptides / chemistry*
  • Peptides / genetics*
  • Protein Conformation
  • Protein Folding
  • Protein Stability
  • Protein Structure, Secondary

Substances

  • Peptides
  • polyproline