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| SELECTIVE IN-VIVO RESCUE BY GROEL/ES OF THERMOLABILE FOLDING INTERMEDIATES TO PHAGE-P22 STRUCTURAL PROTEINS |
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| Author(s): GORDON CL, SATHER SK, CASJENS S, KING J |
| Source: JOURNAL OF BIOLOGICAL CHEMISTRY Volume: 269 Issue: 45 Pages: 27941-27951 Published: NOV 11 1994 |
| Times Cited: 68 References: 87 |
| Abstract: The in vivo conformational substrates of the GroE chaperonins have been difficult to identify, in part because of limited information on in vivo polypeptide chain folding pathways. Temperature-sensitive folding (tsf) mutants have been characterized for the coat protein and tailspike protein of phage P22. These mutations block intracellular folding at restrictive temperature by increasing the lability of folding intermediates without impairing the stability or function of the native state. Overexpression of GroEL/ES suppressed the defects of tsf mutants at 17 sites in the coat protein, by improving folding efficiency rather than assembly efficiency or protein stability. Immunoprecipitation experiments demonstrated that GroEL interacted transiently with newly synthesized mild-type coat protein and that this interaction was prolonged by the tsf mutations. Folding defects of the tailspike polypeptide chains were not suppressed. A fraction of the tsf mutant tailspike chains bound to GroEL but were inefficiently discharged. The results suggest that 1) thermolabile folding intermediates are natural substrates of GroEL/ES; 2) although GroEL may bind such intermediates for many proteins, the chaperoning function is limited to a subset of substrate proteins; and 3) a key reason for the heat-shock response may be to stabilize thermolabile folding intermediates at elevated temperatures. |
| Document Type: Article |
| Language: English |
Addresses:
1. MIT, DEPT BIOL, CAMBRIDGE, MA 02139 USA
2. UNIV UTAH, MED CTR, DEPT CELLULAR VIRAL & MOLEC BIOL, SALT LAKE CITY, UT 84112 USA |
| Publisher: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 |
| Subject Category: Biochemistry & Molecular Biology |
| IDS Number: PV772 |
| ISSN: 0021-9258 |
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