Chaperonins and protein folding: unity and disunity of mechanisms.
Chaperonin-facilitated folding of proteins involves two partial reactions. The first partial reaction, the formation of stable binary complexes between chaperonin-60 and non-native states of the target protein, is common to the chaperonin-facilitated folding of all target proteins investigated to date. The structural basis for this interaction is not presently understood. The second partial reaction, the dissociation of the target protein in a form committed to the native state, appears to proceed by a variety of mechanisms, dependent upon the nature of the target protein in question. Those target proteins (e.g. rubisco, rhodanese, citrate synthase) which require the presence of chaperonin-10, also appear to require the hydrolysis of ATP to bring about the dissociation of the target protein from chaperonin-60. With one exception (pre-beta-lactamase) those target proteins which do not require the presence of chaperonin-10 to be released from chaperonin-60, also do not require the hydrolysis of ATP, since non-hydrolysable analogues of ATP support the release of the target protein in a state committed to the native state. The question of whether or not chaperonin-facilitated folding constitutes a catalysed event is addressed.
Lorimer
G H
GH
Central Research and Development Department, Dupont Company Experimental Station E402, Wilmington, Delaware 19880.
Todd
M J
MJ
Viitanen
P V
PV
D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D018835:Chaperonin 10; D018834:Chaperonin 60; D018833:Chaperonins; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D008954:Models, Biological; D017510:Protein Folding; D011506:Proteins / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000096:biosynthesis*
D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D006360:Heat-Shock Proteins; D011506:Proteins; D018833:Chaperonins; D012273:Ribulose-Bisphosphate Carboxylase