Mechanism of GroEL action: productive release of polypeptide from a sequestered position under GroES
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Summary
This summary is machine-generated.The chaperonin GroEL-GroES system assists protein folding via a two-step mechanism. GroES sequesters proteins, and ATP hydrolysis drives their release and productive folding.
Area Of Science
- Molecular Biology
- Biochemistry
- Protein Folding
Background
- The chaperonin GroEL, with cochaperonin GroES and ATP, facilitates protein folding in vivo.
- GroEL is a double-ring structure; GroES binds asymmetrically to one GroEL ring.
Purpose Of The Study
- To elucidate the mechanism of GroEL-GroES mediated protein folding.
- To investigate polypeptide binding and release dynamics within the GroEL complex.
Main Methods
- Cross-linking studies to identify polypeptide binding sites.
- Single turnover experiments using ornithine transcarbamylase.
- Analysis of GroEL-GroES complex formation and dissociation.
Main Results
- Polypeptide binding occurs on the GroEL ring not occupied by GroES (trans complex).
- Released GroES can rebind to the GroEL ring containing polypeptide (cis complex).
- Polypeptides are protected in cis complexes with ADP and productively released from cis, not trans, complexes.
Conclusions
- A two-step mechanism for GroEL-mediated folding is proposed.
- Step 1: GroES displaces and sequesters polypeptide within the GroEL cavity.
- Step 2: ATP hydrolysis triggers GroES release and productive polypeptide release.