Nested allosteric interactions in the cytoplasmic chaperonin containing TCP-1.
Initial rates of ATP hydrolysis by the chaperonin containing TCP-1 (CCT) from bovine testis were measured as a function of ATP concentration. Two allosteric transitions are observed: one at relatively low concentrations of ATP (<100 microM) and the second at higher concentrations of ATP. The data suggest that CCT has positive intra-ring cooperativity and negative inter-ring cooperativity in ATP hydrolysis, with respect to ATP, as previously observed in the case of GroEL. It is shown that the relatively weak positive intra-ring cooperativity found in the case of CCT may be due to heterogeneity in its subunit composition. Our results suggest that nested allosteric behavior may be common to chaperone double-ring systems.
Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
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G
Kafri
K R
KR
Willison
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A
Horovitz
D000255:Adenosine Triphosphate / Q000378:metabolism; D000495:Allosteric Site; D000818:Animals; D002417:Cattle; D018834:Chaperonin 60 / Q000737:chemistry; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins / Q000737:chemistry*; D003593:Cytoplasm / Q000737:chemistry*; D019281:Dimerization; D006868:Hydrolysis; D007700:Kinetics; D008297:Male; D011485:Protein Binding; D013737:Testis / Q000737:chemistry*
D018834:Chaperonin 60; D000255:Adenosine Triphosphate; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins