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Protein memory through altered folding mediated by intramolecular chaperones
U P Shinde1, J J Liu, M Inouye
1Department of Biochemistry, Robert Wood Johnson Medical School-UMDNJ, Piscataway, New Jersey 08854, USA.
Nature
|October 23, 1997
Summary
Subtilisin propeptides act as intramolecular chaperones, guiding protease domain folding. A mutation in the chaperone creates an
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Folding
Background:
- The propeptide of subtilisin functions as an intramolecular chaperone.
- This mechanism is conserved across prokaryotic and eukaryotic proteins, including prohormone-convertases.
Purpose of the Study:
- To investigate the role of the subtilisin propeptide as an intramolecular chaperone.
- To determine if mutations in the chaperone can induce altered protein conformations.
Main Methods:
- Site-directed mutagenesis of the subtilisin propeptide (Ile(-48)-to-Val).
- Analysis of enzyme kinetics, amino acid sequence (sequencing and mass spectrometry), chaperone binding affinity, secondary structure, thermostability, and substrate specificity of wild-type and mutant subtilisin E.
Main Results:
- A mutated intramolecular chaperone induced an 'altered' enzymatically active conformation in subtilisin E.
- Despite identical amino acid sequences, altered and wild-type subtilisins exhibited distinct chaperone binding affinities, secondary structures, thermostability, and substrate specificities.
- The altered subtilisin showed a 4.5-fold greater affinity for its cognate chaperone compared to non-cognate chaperones.
Conclusions:
- An identical polypeptide can fold into distinct conformations influenced by mutations in its intramolecular chaperone.
- This phenomenon, termed 'protein memory,' suggests that the folding pathway can leave a lasting imprint on protein structure and function.
- Protein memory may have significant implications for understanding protein folding and misfolding diseases.