Kinetic characterization of early intermediates in the folding of E. coli tryptophan-synthase beta 2 subunit.
This report describes the use of fluorescence energy transfer between an intrinsic energy donor (tryptophan 177) and two chemically added acceptors to study intermediates in the folding of the beta 2 subunit of E. coli tryptophan-synthase. Two early folding steps are thus identified and characterized. One is very rapid (its rate constant at 12 degrees C is 0.02 sec-1) and corresponds to the folding of the N-terminal domain into a structure whose overall features approximate well those of the native domain. The second step is somewhat slower (its rate constant at 12 degrees C is 0.008 sec-1) and involves a conformational rearrangement of the N-terminal domain brought about by the interactions between the N- and C-terminal domains within a monomeric beta chain. This brings to five the number of intermediates which have been identified and ordered on the folding pathway of the dimeric beta 2 subunit.
Blond
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Département de Biochimie et Génétique Moléculaire, Institut Pasteur, Paris, France.
Goldberg
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D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D009282:Naphthalenesulfonates; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D011487:Protein Conformation; D011489:Protein Denaturation; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014367:Tryptophan Synthase / Q000378:metabolism*
D009282:Naphthalenesulfonates; D010446:Peptide Fragments; C006421:1,5-I-AEDANS; D014367:Tryptophan Synthase