title: Amphipathic lipid packing sensor motifs: probing bilayer defects with hydrophobic residues.
abstract: Sensing membrane curvature allows fine-tuning of complex reactions that occur at the surface of membrane-bound organelles. One of the most sensitive membrane curvature sensors, the Amphipathic Lipid Packing Sensor (ALPS) motif, does not seem to recognize the curved surface geometry of membranes per se; rather, it recognizes defects in lipid packing that arise from membrane bending. In a companion paper, we show that these defects can be mimicked by introducing conical lipids in a flat lipid bilayer, in agreement with experimental observations. Here, we use molecular-dynamics (MD) simulations to characterize ALPS binding to such lipid bilayers. The ALPS motif recognizes lipid-packing defects by a conserved mechanism: peptide partitioning is driven by the insertion of hydrophobic residues into large packing defects that are preformed in the bilayer. This insertion induces only minor modifications in the statistical distribution of the free packing defects. ALPS insertion is severely hampered when monounsaturated lipids are replaced by saturated lipids, leading to a decrease in packing defects. We propose that the hypersensitivity of ALPS motifs to lipid packing defects results from the repetitive use of hydrophobic insertions along the monotonous ALPS sequence.
authors: Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis and Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7275, Valbonne, France.
authors: Stefano
authors: S
authors: Vanni
authors: Lydie
authors: L
authors: Vamparys
authors: Romain
authors: R
authors: Gautier
authors: Guillaume
authors: G
authors: Drin
authors: Catherine
authors: C
authors: Etchebest
authors: Patrick F J
authors: PF
authors: Fuchs
authors: Bruno
authors: B
authors: Antonny
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D020690:GTPase-Activating Proteins / Q000737:chemistry* / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D020690:GTPase-Activating Proteins; D008051:Lipid Bilayers; D008055:Lipids