1. Autoinhibition and activation mechanisms of the eukaryotic lipid flippase Drs2p-Cdc50p.
- Author
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Bai L, Kovach A, You Q, Hsu HC, Zhao G, and Li H
- Subjects
- Adenosine Triphosphate metabolism, Binding Sites, Calcium-Transporting ATPases chemistry, Calcium-Transporting ATPases metabolism, Calcium-Transporting ATPases ultrastructure, Models, Molecular, Phosphatidylinositol Phosphates metabolism, Protein Conformation, Saccharomyces cerevisiae Proteins chemistry, Saccharomyces cerevisiae Proteins metabolism, Saccharomyces cerevisiae Proteins ultrastructure, Substrate Specificity, Calcium-Transporting ATPases antagonists & inhibitors, Lipids chemistry, Saccharomyces cerevisiae enzymology, Saccharomyces cerevisiae Proteins antagonists & inhibitors
- Abstract
The heterodimeric eukaryotic Drs2p-Cdc50p complex is a lipid flippase that maintains cell membrane asymmetry. The enzyme complex exists in an autoinhibited form in the absence of an activator and is specifically activated by phosphatidylinositol-4-phosphate (PI4P), although the underlying mechanisms have been unclear. Here we report the cryo-EM structures of intact Drs2p-Cdc50p isolated from S. cerevisiae in apo form and in the PI4P-activated form at 2.8 Å and 3.3 Å resolution, respectively. The structures reveal that the Drs2p C-terminus lines a long groove in the cytosolic regulatory region to inhibit the flippase activity. PIP4 binding in a cytosol-proximal membrane region triggers a 90° rotation of a cytosolic helix switch that is located just upstream of the inhibitory C-terminal peptide. The rotation of the helix switch dislodges the C-terminus from the regulatory region, activating the flippase.
- Published
- 2019
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