Related Experiment Videos
Dislocation of membrane proteins in FtsH-mediated proteolysis
1Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
The EMBO Journal
|June 5, 1999
Summary
Escherichia coli FtsH protease degrades membrane proteins, including transmembrane and periplasmic regions, if they are unfolded. Tightly folded domains halt FtsH degradation, suggesting a mechanism for substrate processing.
Area of Science:
- Molecular Biology
- Protein Degradation
- Escherichia coli Research
Background:
- Escherichia coli FtsH is an ATP-dependent metalloprotease.
- FtsH degrades integral membrane proteins like YccA and SecY.
- Proteolysis initiates at the cytosolic N-terminus.
Purpose of the Study:
- Investigate if FtsH proteolysis extends into transmembrane and periplasmic regions.
- Determine the role of protein folding in FtsH-mediated degradation.
- Elucidate the mechanism of FtsH substrate processing.
Main Methods:
- Constructed chimeric proteins (YccA-PhoA, SecY-PhoA) with alkaline phosphatase (PhoA) in periplasmic domains.
- Assessed degradation of PhoA and transmembrane-periplasmic regions by FtsH.
- Evaluated the impact of DsbA-dependent folding on degradation.
Main Results:
- FtsH rapidly degraded unfolded PhoA domains within fusion proteins.
- Independent PhoA or SecY TM9-PhoA regions were stable.
- DsbA-dependent folding halted FtsH degradation near the PhoA N-terminus.
- Degradation efficiency correlated with PhoA folding speed.
Conclusions:
- FtsH performs processive proteolysis on transmembrane and periplasmic domains of unfolded substrates.
- Protein folding acts as a barrier to FtsH-mediated degradation.
- FtsH may translocate extracytoplasmic domains using ATPase activity.