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Evidence for a Lipochaperonin: Association of Active Protein-Folding GroESL Oligomers with Lipids can Stabilize Membranes under Heat Shock Conditions
Zsolt Torok, Ibolya Horvath, Pierre Goloubinoff, Eszter Kovacs, Attila Glatz, Gabor Balogh and Laszlo Vigh
Proceedings of the National Academy of Sciences of the United States of America
Vol. 94, No. 6 (Mar. 18, 1997), pp. 2192-2197
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/41613
Page Count: 6
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During heat shock, structural changes in proteins and membranes may lead to cell death. While GroE and other chaperone proteins are involved in the prevention of stress-induced protein aggregation and in the recovery of protein structures, a mechanism for short-term membrane stabilization during stress remains to be established. We found that GroEL chaperonin can associate with model lipid membranes. Binding was apparently governed by the composition and the physical state of the host bilayer. Limited proteolysis of GroEL oligomers by proteinase K, which removes selectively the conserved glycine- and methionine-rich C terminus, leaving the chaperonin oligomer intact, prevented chaperonin association with lipid membranes. GroEL increased the lipid order in the liquid crystalline state, yet remained functional as a protein-folding chaperonin. This suggests that, during stress, chaperonins can assume the functions of assisting the folding of both soluble and membrane-associated proteins while concomitantly stabilizing lipid membranes.
Proceedings of the National Academy of Sciences of the United States of America © 1997 National Academy of Sciences