title: Regulation of the Ca(2+)-ATPase by cholesterol: a specific or non-specific effect?
abstract: Like other integral membrane proteins, the activity of the Sarco/Endoplasmic Reticulum Ca(2+)-ATPase (SERCA) is regulated by the membrane environment. Cholesterol is present in the endoplasmic reticulum membrane at low levels, and it has the potential to affect SERCA activity both through direct, specific interaction with the protein or through indirect interaction through changes of the overall membrane properties. There are experimental data arguing for both modes of action for a cholesterol-mediated regulation of SERCA. In the current study, coarse-grained molecular dynamics simulations are used to address how a mixed lipid-cholesterol membrane interacts with SERCA. Candidates for direct regulatory sites with specific cholesterol binding modes are extracted from the simulations. The binding pocket for thapsigargin, a nanomolar inhibitor of SERCA, has been suggested as a cholesterol binding site. However, the thapsigargin binding pocket displayed very little cholesterol occupation in the simulations. Neither did atomistic simulations of cholesterol in the thapsigargin binding pocket support any specific interaction. The current study points to a non-specific effect of cholesterol on SERCA activity, and offers an alternative interpretation of the experimental results used to argue for a specific effect.
authors.affiliation: a Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation , Aarhus , Denmark .|b Department of Molecular Biology and Genetics , Aarhus University , Aarhus , Denmark .
authors.forename: Henriette Elisabeth
authors.initials: HE
authors.lastname: Autzen
authors.affiliation: a Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation , Aarhus , Denmark .|c Bioinformatics Research Centre (BiRC) , Aarhus , Denmark , and.
authors.forename: Iwona
authors.initials: I
authors.lastname: Siuda
authors.affiliation: a Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation , Aarhus , Denmark .|b Department of Molecular Biology and Genetics , Aarhus University , Aarhus , Denmark .
authors.forename: Yonathan
authors.initials: Y
authors.lastname: Sonntag
authors.affiliation: a Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation , Aarhus , Denmark .|b Department of Molecular Biology and Genetics , Aarhus University , Aarhus , Denmark .
authors.forename: Poul
authors.initials: P
authors.lastname: Nissen
authors.affiliation: a Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation , Aarhus , Denmark .|d Department of Biomedicine , Aarhus University , Aarhus , Denmark.
authors.forename: Jesper Vuust
authors.initials: JV
authors.lastname: Møller
authors.affiliation: a Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation , Aarhus , Denmark .|c Bioinformatics Research Centre (BiRC) , Aarhus , Denmark , and.
authors.forename: Lea
authors.initials: L
authors.lastname: Thøgersen
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*; D019284:Thapsigargin / Q000378:metabolism
chemical_list: D019284:Thapsigargin; D002784:Cholesterol; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases
keywords: Cholesterol; non-annular binders; sarco(endo)plasmic reticulum Ca2+ ATPase