title: Folding of maltose-binding protein. Evidence for the identity of the rate-determining step in vivo and in vitro.
abstract: The folding of maltose-binding protein, a periplasmic protein in Escherichia coli, was shown to proceed through the same rate-limiting step whether folding occurred in the cell under physiological conditions or in vitro in the absence of other proteins. Four species of maltose-binding protein containing aminoacyl substitutions identified as decreasing the rate of folding of the protein in vivo were purified, and their denaturant-induced folding transitions were analyzed by monitoring the intrinsic fluorescence of tryptophan. In all four cases the rate of folding in vitro was slower than that of the wild-type maltose-binding protein; thus the same step determines the rate of folding in vivo and in vitro. Furthermore, examination of the three-dimensional structure of maltose-binding protein as determined by x-ray crystallography (F. Quiocho, personal communication; Spurlino, J. C., Lu, G.-Y., and Quiocho, F. A. (1991) J. Biol. Chem. 266, 5202-5219) indicates that all 4 of the residues identified as crucial to folding lie in one structural element of the native protein. We conclude that the rate-limiting step both in vivo and in vitro involves formation of this element of structure.
authors.affiliation: Program in Genetics and Cell Biology, Washington State University, Pullman 99164-4660.
authors.forename: S Y
authors.initials: SY
authors.lastname: Chun
authors.forename: S
authors.initials: S
authors.lastname: Strobel
authors.forename: P
authors.initials: P
authors.lastname: Bassford
authors.forename: L L
authors.initials: LL
authors.lastname: Randall
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000215:Acylation; D001426:Bacterial Proteins / Q000737:chemistry*; D002352:Carrier Proteins / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins; D007700:Kinetics; D008320:Maltose; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D017510:Protein Folding; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; C461599:maltose transport system, E coli; D008320:Maltose