Open AccessStructure and Calcium Binding Properties of a Neuronal Calcium-Myristoyl Switch Protein, Visinin-Like Protein 3
Author(s) -
Congmin Li,
Sunghyuk Lim,
Karl-Heinz Braunewell,
James B. Ames
Publication year - 2016
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0165921
Subject(s) - myristoylation , recoverin , biophysics , protein structure , calcium binding protein , plasma protein binding , calcium , chemistry , biology , biochemistry , crystallography , phosphorylation , rhodopsin , organic chemistry , retinal
Visinin-like protein 3 (VILIP-3) belongs to a family of Ca 2+ -myristoyl switch proteins that regulate signal transduction in the brain and retina. Here we analyze Ca 2+ binding, characterize Ca 2+ -induced conformational changes, and determine the NMR structure of myristoylated VILIP-3. Three Ca 2+ bind cooperatively to VILIP-3 at EF2, EF3 and EF4 (K D = 0.52 μM and Hill slope of 1.8). NMR assignments, mutagenesis and structural analysis indicate that the covalently attached myristoyl group is solvent exposed in Ca 2+ -bound VILIP-3, whereas Ca 2+ -free VILIP-3 contains a sequestered myristoyl group that interacts with protein residues (E26, Y64, V68), which are distinct from myristate contacts seen in other Ca 2+ -myristoyl switch proteins. The myristoyl group in VILIP-3 forms an unusual L-shaped structure that places the C 14 methyl group inside a shallow protein groove, in contrast to the much deeper myristoyl binding pockets observed for recoverin, NCS-1 and GCAP1. Thus, the myristoylated VILIP-3 protein structure determined in this study is quite different from those of other known myristoyl switch proteins (recoverin, NCS-1, and GCAP1). We propose that myristoylation serves to fine tune the three-dimensional structures of neuronal calcium sensor proteins as a means of generating functional diversity.