1. Phosphorylation of Ykt6 SNARE Domain Regulates Its Membrane Recruitment and Activity
- Author
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Julia Christina Gross, Adi Danieli-Mackay, Leonie Witte, Dolma Choezom, Pradhipa Karuna M, Karen Linnemannstoens, and Mona Honemann-Capito
- Subjects
Conformational change ,lcsh:QR1-502 ,Biochemistry ,Membrane Fusion ,lcsh:Microbiology ,Article ,Animals, Genetically Modified ,R-SNARE Proteins ,03 medical and health sciences ,0302 clinical medicine ,Ykt6 conformational switch ,Organelle ,Animals ,Drosophila Proteins ,Humans ,Secretion ,Amino Acid Sequence ,Phosphorylation ,Molecular Biology ,Secretory pathway ,030304 developmental biology ,0303 health sciences ,Chemistry ,Lipid bilayer fusion ,Extracellular vesicle ,HCT116 Cells ,Cell biology ,secretory pathway ,Transmembrane domain ,HEK293 Cells ,membrane attachment ,Drosophila ,protein trafficking ,SNARE Proteins ,030217 neurology & neurosurgery - Abstract
Sensitive factor attachment protein receptors (SNARE) proteins are important mediators of protein trafficking that regulate the membrane fusion of specific vesicle populations and their target organelles. The SNARE protein Ykt6 lacks a transmembrane domain and attaches to different organelle membranes. Mechanistically, Ykt6 activity is thought to be regulated by a conformational change from a closed cytosolic form to an open membrane-bound form, yet the mechanism that regulates this transition is unknown. We identified phosphorylation sites in the SNARE domain of Ykt6 that mediate Ykt6 membrane recruitment and are essential for cellular growth. Using proximity-dependent labeling and membrane fractionation, we found that phosphorylation regulates Ykt6 conversion from a closed to an open conformation. This conformational switch recruits Ykt6 to several organelle membranes, where it functionally regulates the trafficking of Wnt proteins and extracellular vesicle secretion in a concentration-dependent manner. We propose that phosphorylation of its SNARE domain leads to a conformational switch from a cytosolic, auto-inhibited Ykt6 to an active SNARE at different membranes.
- Published
- 2020