Selective in vivo rescue by GroEL/ES of thermolabile folding intermediates to phage P22 structural proteins
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...
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Published in | The Journal of biological chemistry Vol. 269; no. 45; pp. 27941 - 27951 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Society for Biochemistry and Molecular Biology
11.11.1994
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Subjects | |
Online Access | Get full text |
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Summary: | 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 wild-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. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)46878-0 |