title: The role of phosphatidic acid and cardiolipin in stability of the tetrameric assembly of potassium channel KcsA.
abstract: In this study, the roles of two anionic phospholipids-phosphatidic acid (PA), which is an important signaling molecule, and cardiolipin (CL), which plays a crucial role in the bioenergetics of the cell-in stabilizing the oligomeric structure of potassium channel KcsA were determined. The stability of KcsA was drastically increased as a function of PA or CL content (mol%) in phosphatidylcholine (PC) bilayers. Deletion of the membrane-associated N terminus significantly reduced channel stability at high levels of PA content; however, the intrinsic stability of this protein was marginally affected in the presence of CL. These studies indicate that the electrostatic-hydrogen bond switch between PA and N terminus, involving basic residues, is much stronger than the stabilizing effect of CL. Furthermore, the unique properties of the PA headgroup alter protein assembly and folding properties differently from the CL headgroup, and both lipids stabilize the tetrameric assembly via their specific interaction on the extra- or the intracellular side of KcsA.
authors.affiliation: Department of Biochemistry of Membranes, Center for Biomembranes and Lipid Enzymology, Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands. mraja@pmcol.ualberta.ca
authors.forename: Mobeen
authors.initials: M
authors.lastname: Raja
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002308:Cardiolipins / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D010712:Phosphatidic Acids / Q000737:chemistry*; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D014270:Trifluoroethanol / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D002308:Cardiolipins; D010712:Phosphatidic Acids; D015221:Potassium Channels; D021122:Protein Subunits; C107790:prokaryotic potassium channel; D014270:Trifluoroethanol