PMID:10497158
Citation |
Zolkiewski, M (1999) ClpB cooperates with DnaK, DnaJ, and GrpE in suppressing protein aggregation. A novel multi-chaperone system from Escherichia coli. J. Biol. Chem. 274:28083-6 |
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Abstract |
ClpB is a heat-shock protein from Escherichia coli with an unknown function. We studied a possible molecular chaperone activity of ClpB in vitro. Firefly luciferase was denatured in urea and then diluted into the refolding buffer (in the presence of 5 mM ATP and 0.1 mg/ml bovine serum albumin). Spontaneous reactivation of luciferase was very weak (less than 0.02% of the native activity) because of extensive aggregation. Conventional chaperone systems (GroEL/GroES and DnaK/DnaJ/GrpE) or ClpB alone did not reactivate luciferase under those conditions. However, ClpB together with DnaK/DnaJ/GrpE greatly enhanced the luciferase activity regain (up to 57% of native activity) by suppressing luciferase aggregation. This coordinated function of ClpB and DnaK/DnaJ/GrpE required ATP hydrolysis, although the ClpB ATPase was not activated by native or denatured luciferase. When the chaperones were added to the luciferase refolding solutions after 5-25 min of refolding, ClpB and DnaK/DnaJ/GrpE recovered the luciferase activity from preformed aggregates. Thus, we have identified a novel multi-chaperone system from E. coli, which is analogous to the Hsp104/Ssa1/Ydj1 system from yeast. ClpB is the only known bacterial Hsp100 protein capable of cooperating with other heat-shock proteins in suppressing and reversing protein aggregation. |
Links | |
Keywords |
Adenosine Triphosphatases/metabolism; Animals; Bacterial Proteins/metabolism; Cattle; Escherichia coli/metabolism; Escherichia coli Proteins; HSP40 Heat-Shock Proteins; HSP70 Heat-Shock Proteins/metabolism; Heat-Shock Proteins/metabolism; Luciferases/metabolism; Molecular Chaperones/metabolism; Protein Renaturation |
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