title: A myristoyl/phosphoserine switch controls cAMP-dependent protein kinase association to membranes.
abstract: The cAMP-dependent protein kinase [protein kinase A (PKA)] mediates a myriad of cellular signaling events, and its activity is tightly regulated in both space and time. Among these regulatory mechanisms is N-myristoylation, whose biological role has been elusive. Using a combination of thermodynamics, kinetics, and spectroscopic methods, we analyzed the effects of N-myristoylation and phosphorylation at Ser10 on the interactions of PKA with model membranes. We found that, in the absence of lipids, the myristoyl group is tucked into the hydrophobic binding pocket of the enzyme (myr-in state). Upon association with lipid bilayers, the myristoyl group is extruded and inserts into the hydrocarbon region of the lipid bilayer (myr-out state). NMR data indicate that the enzyme undergoes conformational equilibrium between myr-in and myr-out states, which can be shifted byeither interaction with membranes and/or phosphorylation at Ser10. Our results provide evidence that the membrane binding motif of the myristoylated C-subunit of PKA (PKA-C) steers the enzyme toward lipids independent of its regulatory subunit or an A-kinase anchoring protein, providing an additional mechanism to localize the enzyme near membrane-bound substrates.
authors: Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
authors: Ece C
authors: EC
authors: Gaffarogullari
authors: Larry R
authors: LR
authors: Masterson
authors: Emily E
authors: EE
authors: Metcalfe
authors: Nathaniel J
authors: NJ
authors: Traaseth
authors: Erica
authors: E
authors: Balatri
authors: Musa M
authors: MM
authors: Musa
authors: Daniel
authors: D
authors: Mullen
authors: Mark D
authors: MD
authors: Distefano
authors: Gianluigi
authors: G
authors: Veglia
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D002942:Circular Dichroism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008051:Lipid Bilayers; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D019814:Myristic Acid / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D011499:Protein Processing, Post-Translational; D021122:Protein Subunits
chemical_list: D008051:Lipid Bilayers; D021122:Protein Subunits; D019814:Myristic Acid; D010768:Phosphoserine; D017868:Cyclic AMP-Dependent Protein Kinases