title: Specific interaction to PIP2 increases the kinetic rate of membrane binding of VILIPs, a subfamily of Neuronal Calcium Sensors (NCS) proteins.
abstract: VIsinin-LIke Proteins (VILIPs) are a subfamily of the Neuronal Calcium Sensor (NCS) proteins, which possess both N-myristoylation and EF-hand motifs allowing for a putative 'calcium-myristoyl switch' regulation mechanism. It has previously been established that myristoyl conjugation increases the affinity of proteins for membranes, but, in many cases, a second feature such as a cluster of positively-charged residues is needed for stable membrane binding. The interaction of two members of this family, VILIP-1 and VILIP-3, with Langmuir monolayers as membrane models has been investigated in order to study the effects of both myristoylation and the highly basic region containing conserved poly-lysine residues on membrane association kinetics and binding properties. Results show that in the presence of calcium, N-myristoylation significantly increases the kinetic rate of VILIP adsorption to the membrane. Additionally, the proteins bind to negatively charged phospholipids independently of the conjugated myristate moiety. Besides the regulatory effect of calcium on the rate of binding presumably due to exposure of the myristoyl moiety ascribed to their putative 'calcium-myristoyl switch', VILIP-1 and -3 also engage specific interactions with biomimetic membranes containing phosphatidylinositol 4,5-bisphosphate (PIP2). The presence of PIP2 increases the membrane association rates of both VILIPs. Taken together, these results show the major kinetic role of N-myristoylation for membrane binding, and highlight the critical role of specific phosphoinositide interactions for membrane association of members of the VILIP family.
authors.affiliation: Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Université Lyon 1, University of Lyon, ICBMS, CNRS UMR 5246, Bât. Curien, 43 bd du 11 Nov. 1918, F-69622 Villeurbanne cedex, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Rebaud
authors.affiliation: Structural Chemistry Program, Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane Qld 4111, Australia.
authors.forename: Conan K
authors.initials: CK
authors.lastname: Wang
authors.affiliation: Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Université Lyon 1, University of Lyon, ICBMS, CNRS UMR 5246, Bât. Curien, 43 bd du 11 Nov. 1918, F-69622 Villeurbanne cedex, France.
authors.forename: Joe
authors.initials: J
authors.lastname: Sarkis
authors.affiliation: Structural Chemistry Program, Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane Qld 4111, Australia.
authors.forename: Lyndel
authors.initials: L
authors.lastname: Mason
authors.affiliation: Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Université Lyon 1, University of Lyon, ICBMS, CNRS UMR 5246, Bât. Curien, 43 bd du 11 Nov. 1918, F-69622 Villeurbanne cedex, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Simon
authors.affiliation: Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Université Lyon 1, University of Lyon, ICBMS, CNRS UMR 5246, Bât. Curien, 43 bd du 11 Nov. 1918, F-69622 Villeurbanne cedex, France.
authors.forename: Loïc J
authors.initials: LJ
authors.lastname: Blum
authors.affiliation: Structural Chemistry Program, Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane Qld 4111, Australia; Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hofmann
authors.affiliation: Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Université Lyon 1, University of Lyon, ICBMS, CNRS UMR 5246, Bât. Curien, 43 bd du 11 Nov. 1918, F-69622 Villeurbanne cedex, France. Electronic address: agnes.girard-egrot@univ-lyon1.fr.
authors.forename: Agnès P
authors.initials: AP
authors.lastname: Girard-Egrot
mesh_terms: D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D054878:Lipoylation; D008567:Membranes, Artificial; D051596:Neurocalcin / Q000737:chemistry / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000737:chemistry / Q000378:metabolism*
chemical_list: C520235:HPCAL1 protein, human; D008567:Membranes, Artificial; D051596:Neurocalcin; D018129:Phosphatidylinositol Phosphates; C496688:VSNL1 protein, human; C060980:phosphatidylinositol 3,4-diphosphate; D002118:Calcium
keywords: Calcium–myristoyl switch; Langmuir monolayer; Neuronal Calcium Sensor (NCS) proteins; Phosphoinositides; Protein–lipid interactions; VIsinin-LIke Proteins (VILIPs)