The GET insertase exhibits conformational plasticity and induces membrane thinning

Area of Science:

• Molecular Biology
• Biochemistry
• Cell Biology

Background:

• The guided entry of tail-anchored proteins (GET) pathway is crucial for inserting tail-anchored (TA) proteins into the endoplasmic reticulum membrane.
• The Get3 chaperone binds TA proteins in the cytosol and delivers them to the Get1/Get2 complex (GET insertase) for membrane insertion.

Purpose of the Study:

• To elucidate the structural and mechanistic basis of TA protein insertion by the GET pathway.
• To investigate the conformational dynamics of the human and Chaetomium thermophilum Get1/Get2/Get3 complex.

Main Methods:

• X-ray crystallography to determine high-resolution structures of the GET complex.
• Atomistic molecular dynamics simulations to analyze conformational changes and membrane interactions.
• Biochemical assays to assess the functional role of specific interactions and membrane thinning.

Main Results:

• The core structure of the GET insertase is conserved across eukaryotes.
• Lipid bilayer thinning near the hydrophilic groove of the insertase facilitates membrane insertion.
• A key interaction between Get2 helix α3' and Get3 triggers conformational changes in the entire GET complex.
• Functional data supports the role of these conformational changes in promoting substrate insertion.

Conclusions:

• The GET insertase exhibits conformational plasticity, enabling it to remodel its membrane environment.
• Understanding these dynamics provides a framework for how TA proteins are efficiently inserted into the ER membrane.