title: Impact of N-terminal myristoylation on the Ca2+-dependent conformational transition in recoverin.
abstract: Recoverin is a Ca2+-regulated signal transduction modulator found in vertebrate retina that has been shown to undergo dramatic conformational changes upon Ca2+ binding to its two functional EF-hand motifs. To elucidate the differential impact of the N-terminal myristoylation as well as occupation of the two Ca2+ binding sites on recoverin structure and function, we have investigated a non-myristoylated E85Q mutant exhibiting virtually no Ca2+ binding to EF-2. Crystal structures of the mutant protein as well as the non-myristoylated wild-type have been determined. Although the non-myristoylated E85Q mutant does not display any functional activity, its three-dimensional structure in the presence of Ca2+ resembles the myristoylated wild-type with two Ca2+ but is quite dissimilar from the myristoylated E85Q mutant. We conclude that the N-terminal myristoyl modification significantly stabilizes the conformation of the Ca2+-free protein (i.e. the T conformation) during the stepwise transition toward the fully Ca2+-occupied state. On the basis of these observations, a refined model for the role of the myristoyl group as an intrinsic allosteric modulator is proposed.
authors.affiliation: Institut für Biologische Informationsverarbeitung IBI-2 (Biologische Strukturforschung), Jülich, Germany.
authors.forename: Oliver H
authors.initials: OH
authors.lastname: Weiergräber
authors.forename: Ivan I
authors.initials: II
authors.lastname: Senin
authors.forename: Pavel P
authors.initials: PP
authors.lastname: Philippov
authors.forename: Joachim
authors.initials: J
authors.lastname: Granzin
authors.forename: Karl-Wilhelm
authors.initials: KW
authors.lastname: Koch
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D014408:Biomarkers, Tumor / Q000737:chemistry / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D002417:Cattle; D018360:Crystallography, X-Ray; D005136:Eye Proteins; D051606:G-Protein-Coupled Receptor Kinase 1; D051597:Hippocalcin; D007700:Kinetics; D008074:Lipoproteins; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D019814:Myristic Acid / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D011485:Protein Binding; D011487:Protein Conformation; D011494:Protein Kinases / Q000378:metabolism; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D051603:Recoverin; D012374:Rod Cell Outer Segment / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D005136:Eye Proteins; D008074:Lipoproteins; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; D019814:Myristic Acid; D051603:Recoverin; D051597:Hippocalcin; D011494:Protein Kinases; D051606:G-Protein-Coupled Receptor Kinase 1; D002118:Calcium