1. Structural Basis of Tail-Anchored Membrane Protein Biogenesis by the GET Insertase Complex.
- Author
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McDowell MA, Heimes M, Fiorentino F, Mehmood S, Farkas Á, Coy-Vergara J, Wu D, Bolla JR, Schmid V, Heinze R, Wild K, Flemming D, Pfeffer S, Schwappach B, Robinson CV, and Sinning I
- Subjects
- Cell Line, Conserved Sequence, Evolution, Molecular, Humans, Membrane Proteins metabolism, Models, Molecular, Phosphatidylinositols metabolism, Protein Binding, Protein Multimerization, Protein Stability, Protein Structure, Secondary, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism, Membrane Proteins biosynthesis, Membrane Proteins chemistry, Multiprotein Complexes metabolism
- Abstract
Membrane protein biogenesis faces the challenge of chaperoning hydrophobic transmembrane helices for faithful membrane insertion. The guided entry of tail-anchored proteins (GET) pathway targets and inserts tail-anchored (TA) proteins into the endoplasmic reticulum (ER) membrane with an insertase (yeast Get1/Get2 or mammalian WRB/CAML) that captures the TA from a cytoplasmic chaperone (Get3 or TRC40, respectively). Here, we present cryo-electron microscopy reconstructions, native mass spectrometry, and structure-based mutagenesis of human WRB/CAML/TRC40 and yeast Get1/Get2/Get3 complexes. Get3 binding to the membrane insertase supports heterotetramer formation, and phosphatidylinositol binding at the heterotetramer interface stabilizes the insertase for efficient TA insertion in vivo. We identify a Get2/CAML cytoplasmic helix that forms a "gating" interaction with Get3/TRC40 important for TA insertion. Structural homology with YidC and the ER membrane protein complex (EMC) implicates an evolutionarily conserved insertion mechanism for divergent substrates utilizing a hydrophilic groove. Thus, we provide a detailed structural and mechanistic framework to understand TA membrane insertion., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 Elsevier Inc. All rights reserved.)
- Published
- 2020
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