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The inter‐ring arrangement of the cytosolic chaperonin CCT
Author(s) -
MartínBenito Jaime,
Grantham Julie,
Boskovic Jasminka,
Brackley Karen I,
Carrascosa José L,
Willison Keith R,
Valpuesta José M
Publication year - 2007
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400894
Subject(s) - cytosol , chaperonin , ring (chemistry) , microbiology and biotechnology , chemistry , biology , genetics , biochemistry , protein folding , enzyme , organic chemistry
The eukaryotic cytosolic chaperonin CCT (chaperonin containing TCP‐1) is the most complex of all chaperonins—an oligomeric structure built from two identical rings, each composed of single copies of eight different subunits. The arrangement of the eight subunits within each ring has been characterised for some time, but the phasing between the two rings remains unknown. Here, three‐dimensional reconstructions generated by cryoelectron microscopy of complexes between CCT and either of two different monoclonal antibodies that react specifically with the CCTε and CCTδ subunits have been used to determine the phasing between the two chaperonin rings. The inter‐ring arrangement is such that up/down inter‐ring communication always involves two different CCT subunits in all eight positions, and the group of subunits concerned with the initiation and completion of the folding cycle cluster together both in the intra‐ and inter‐ring arrangement. This supports a sequential mechanism of conformational changes between the two interacting rings.