Folding of maltose-binding protein. Evidence for the identity of the rate-determining step in vivo and in vitro.
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.
Chun
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Program in Genetics and Cell Biology, Washington State University, Pullman 99164-4660.
Strobel
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Bassford
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Randall
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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
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