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Mechanism of Action of Group II Chaperonins:. Impact of the Built-in Lid on the Conformational Cycle
Mechanism of Action of Group II Chaperonins:. Impact of the Built-in Lid on the Conformational Cycle
Chaperonins are highly allosteric double-ring ATPases that mediate cellular protein folding. ATP binding and hydrolysis control opening and closing of the central chaperonin chamber which transiently provides a protected environment for protein folding. During evolution, two distinct strategies to close the chaperonin chamber have emerged. Archaeal and eukaryotic chaperonins contain a built-in lid, whereas bacterial chaperonins use a ring-shaped cofactor as a detachable lid. The present work contributes to the current mechanistical understanding of group II chaperonins by unraveling key functions of the built-in lid. In addition to physically encapsulating the substrate, the lid-forming apical protrusions also play a key role in regulating chaperonin function and ensuring its activity as a “two-stroke” molecular machine. By comparative investigation of two distinct chaperonin systems, namely TRiC and Mm-Cpn, this study uncovers a remarkable degree of mechanistic and functional conservation between group II chaperonins from eukaryotic and archaeal origin, despite their evolutionary distance.
chaperonin, allostery, protein folding
Reißmann, Stefanie
2007
English
Universitätsbibliothek der Ludwig-Maximilians-Universität München
Reißmann, Stefanie (2007): Mechanism of Action of Group II Chaperonins:: Impact of the Built-in Lid on the Conformational Cycle. Dissertation, LMU München: Faculty of Biology
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Abstract

Chaperonins are highly allosteric double-ring ATPases that mediate cellular protein folding. ATP binding and hydrolysis control opening and closing of the central chaperonin chamber which transiently provides a protected environment for protein folding. During evolution, two distinct strategies to close the chaperonin chamber have emerged. Archaeal and eukaryotic chaperonins contain a built-in lid, whereas bacterial chaperonins use a ring-shaped cofactor as a detachable lid. The present work contributes to the current mechanistical understanding of group II chaperonins by unraveling key functions of the built-in lid. In addition to physically encapsulating the substrate, the lid-forming apical protrusions also play a key role in regulating chaperonin function and ensuring its activity as a “two-stroke” molecular machine. By comparative investigation of two distinct chaperonin systems, namely TRiC and Mm-Cpn, this study uncovers a remarkable degree of mechanistic and functional conservation between group II chaperonins from eukaryotic and archaeal origin, despite their evolutionary distance.