The amphipathic helix of an enzyme that regulates phosphatidylcholine synthesis remodels membranes into highly curved nanotubules
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Graphical abstract
Highlights
► Membrane binding activates CCT and also locally remodels the bilayer. ► The CCT amphipathic helix is necessary and sufficient for lipid vesicle tubulation. ► Nanotubes 11–12 nm in diameter can form with a density of 1 CCT/50 lipids. ► Pathways for nanotube generation are variable, and depend on vesicle lipid composition. ► CCT tubulation efficiency scales with amphipathic helix length, not binding affinity.
Abbreviations
CCT
CTP:phosphocholine cytidylyltransferase
AH
amphipathic helix
NLS
nuclear localization sequence
DMPC
1,2-dimyristoyl-sn-glycerophosphocholine
DMPC
1,2-dimyristoyl-sn-glycerophosphoglycerol (sodium salt)
DAG
diacylglycerol
POPS
1-palmytoyl-2-oleoyl-sn-glycero-3-[phospho-l-serine] (sodium salt)
POPE
1-palmitoyl-2-oleoyl-sn-glycero-3-phospholethanolamine
PI
bovine liver phosphatidyl inositol
SM
egg sphingomyelin
DTT
1,4-dithio-d-threitol
SUVs
sonicated unilamellar vesicles
MLVs
multilamellar vesicles
LUVs
large unilamellar vesicles
SLVs
sucrose-loaded vesicles
NE
nuclear envelope
PM
phosphomimic
NE mix
LUVs composed of egg PC/POPE/PI /POPS/SM (55/20/10/10/5), PBS, phosphate buffered saline
TEM
transmission electron microscopy
Keywords
CTP:phosphocholine cytidylyltransferase
Membrane curvature
Vesicle tubulation
Electron microscopy
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