Fast and faster: a designed variant of the B-domain of protein A folds in 3 microsec

Protein Sci. 2004 Apr;13(4):847-53. doi: 10.1110/ps.03541304.

Abstract

We have introduced the mutation glycine 29 to alanine, designed to increase the rate of protein folding, into the B-domain of protein A (BdpA). From NMR lineshape analysis, we find the G29A mutation increases the folding rate constant by threefold; the folding time is 3 microsec. Although wild-type BdpA folds extremely fast, simple-point mutations can still speed up the folding; thus, the folding rate is not evolutionarily maximized. The short folding time of G29A BdpA (the shortest time yet reported) makes it an attractive candidate for an all-atom molecular dynamics simulation that could potentially show a complete folding reaction starting from an extended chain. We also constructed a fluorescent variant of BdpA by mutating phenylalanine 13 to tryptophan, allowing fluorescence-based time-resolved temperature-jump measurements. Temperature jumps and NMR complement each other, and give a very complete picture of the folding kinetics.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Substitution / genetics
  • Kinetics
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Protein Denaturation
  • Protein Folding*
  • Protein Structure, Tertiary / genetics
  • Staphylococcal Protein A / chemistry*
  • Staphylococcal Protein A / genetics

Substances

  • Staphylococcal Protein A