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How does Sec63 affect the conformation of Sec61 in yeast?
Pratiti Bhadra1, Lalitha Yadhanapudi2, Karin Römisch2
1Center for Bioinformatics, Saarland University, Saarbrücken, Saarland, Germany.
Plos Computational Biology
|March 29, 2021
Summary
The Sec63 protein interacts with the Sec61 channel, influencing its structure and function in protein translocation. This interaction is crucial for guiding signal anchors of specific substrates, independent of the Sbh1 subunit.
Area of Science:
- Cellular Biology
- Protein Translocation
- Structural Biology
Background:
- The Sec complex facilitates protein transport into the endoplasmic reticulum.
- Accessory proteins like Sec63 are essential for certain substrate translocations.
- Previous cryo-EM studies elucidated the structure of the Sec complex.
Purpose of the Study:
- To investigate the role of Sec63 in the Sec complex structure and function.
- To determine if the Sbh1 subunit is necessary for Sec63-Sec61 interactions.
- To elucidate the mechanism by which Sec63 influences Sec61 channel conformation.
Main Methods:
- Co-precipitation assays to study protein interactions.
- Molecular dynamics simulations to analyze conformational changes.
- Molecular docking to assess substrate peptide interactions.
Main Results:
- Sec61 channel subunit Sbh1 is not required for stable Sec63-Sec61 complex formation.
- Sec63 binding induces conformational changes in the Sec61 channel's lateral gate, plug, and pore.
- Sec63-mediated alterations in the Sec61 pore are critical for positioning signal anchors of SRP-dependent substrates.
Conclusions:
- Sec63 directly modulates the Sec61 channel's structure and dynamics.
- These structural changes are key to the regulated translocation of specific secretory proteins.
- The findings provide mechanistic insights into protein targeting and insertion into the ER membrane.
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