An Expanded Conformation of Single-Ring GroEL-GroES Complex Encapsulates an 86 kDa Substrate

Dong Hua Chen, Jiu Li Song, David T. Chuang, Wah Chiu, Steven J. Ludtke

Research output: Contribution to journalArticle

49 Scopus citations

Abstract

Electron cryomicroscopy reveals an unprecedented conformation of the single-ring mutant of GroEL (SR398) bound to GroES in the presence of Mg-ATP. This conformation exhibits a considerable expansion of the folding cavity, with ∼80% more volume than the X-ray structure of the equivalent cis cavity in the GroEL-GroES-(ADP)7 complex. This expanded conformation can encapsulate an 86 kDa heterodimeric (αβ) assembly intermediate of mitochondrial branched-chain α-ketoacid dehydrogenase, the largest substrate ever observed to be cis encapsulated. The SR398-GroES-Mg-ATP complex is found to exist as a mixture of standard and expanded conformations, regardless of the absence or presence of the substrate. However, the presence of even a small substrate causes a pronounced bias toward the expanded conformation. Encapsulation of the large assembly intermediate is supported by a series of electron cryomicroscopy studies as well as the protection of both α and β subunits of the substrate from tryptic digestion.

Original languageEnglish (US)
Pages (from-to)1711-1722
Number of pages12
JournalStructure
Volume14
Issue number11
DOIs
StatePublished - Nov 1 2006

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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