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A filamentous molecular chaperone of the prefoldin family from the deep‐sea hyperthermophile Methanocaldococcus jannaschii
Author(s) -
Whitehead Timothy A.,
Boonyaratanakornkit Boonchai B.,
Höllrigl Volker,
Clark Douglas S.
Publication year - 2007
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.062599907
Subject(s) - hyperthermophile , chaperone (clinical) , archaea , random hexamer , biology , protein subunit , methanococcus , biophysics , biochemistry , protein folding , microbiology and biotechnology , chemistry , gene , medicine , pathology
Prefoldin is a molecular chaperone found in the domains eukarya and archaea that acts in conjunction with Group II chaperonin to correctly fold other nascent proteins. Previously, our group identified a putative single subunit of prefoldin, γ PFD, that was up‐regulated in response to heat stress in the hyperthermophilic archaeon Methanocaldococcus jannaschii . In order to characterize this protein, we subcloned and expressed it and the other two prefoldin subunits from M. jannaschii , α and β PFD, into Eschericia coli and characterized the proteins. Whereas α and β PFD readily assembled into the expected hexamer, γ PFD would not assemble with either protein. Instead, γ PFD forms long filaments of defined dimensions measuring 8.5 nm × 1.7–3.5 nm and lengths exceeding 1 μm. Filamentous γ PFD acts as a molecular chaperone through in vitro assays, in a manner comparable to PFD. A possible molecular model for filament assembly is discussed.