title: Defining the intramembrane binding mechanism of sarcolipin to calcium ATPase using solution NMR spectroscopy.
abstract: Sarcolipin (SLN) is an integral membrane protein that is expressed in both skeletal and cardiac muscle, where it inhibits SERCA (calcium ATPase) by lowering its apparent Ca2+ affinity in a manner similar to that of its homologue phospholamban (PLN). We use solution NMR to map the structural changes occurring within SLN upon interaction with the regulatory target, SERCA, co-reconstituting the two proteins in dodecylphosphocholine (DPC) detergent micelles, a system that preserves the native structure of SLN and the activity of SERCA, with the goal of comparing these interactions with those of the previously studied PLN-SERCA complex. Our analysis of the structural dynamics of SLN in DPC micelles shows this polypeptide to be partitioned into four subdomains: a short unstructured N terminus (residues 1-6), a short dynamic helix (residues 7-14), a more rigid helix (residues 15-26), and an unstructured C terminus (residues 27-31). Upon addition of SERCA, the different domains behave according to their dynamics, molding onto the surface of the enzyme. Remarkably, each domain of SLN behaves in a manner similar to that of the corresponding domains in PLN, supporting the hypothesis that both SLN and PLN bind SERCA in the same groove and with similar mechanisms.
authors.affiliation: Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Jarrod J
authors.initials: JJ
authors.lastname: Buffy
authors.forename: Bethany A
authors.initials: BA
authors.lastname: Buck-Koehntop
authors.forename: Fernando
authors.initials: F
authors.lastname: Porcelli
authors.forename: Nathaniel J
authors.initials: NJ
authors.lastname: Traaseth
authors.forename: David D
authors.initials: DD
authors.lastname: Thomas
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Veglia
mesh_terms: D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D009124:Muscle Proteins / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011510:Proteolipids / Q000378:metabolism*; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases
chemical_list: D008823:Micelles; D009124:Muscle Proteins; D011510:Proteolipids; C077258:sarcolipin; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D002118:Calcium