title: Fast and faster: a designed variant of the B-domain of protein A folds in 3 microsec.
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.
authors.affiliation: Department of Biochemistry, Vanderbilt University Medical Center, 5140 MRB III, 465 21st Avenue South, Nashville, TN 37232-8725, USA.
authors.forename: Pooja
authors.initials: P
authors.lastname: Arora
authors.forename: Terrence G
authors.initials: TG
authors.lastname: Oas
authors.forename: Jeffrey K
authors.initials: JK
authors.lastname: Myers
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000235:genetics; D013205:Staphylococcal Protein A / Q000737:chemistry* / Q000235:genetics
chemical_list: D013205:Staphylococcal Protein A