Lateral sequestration of phosphatidylinositol 4,5-bisphosphate by the basic effector domain of myristoylated alanine-rich C kinase substrate is due to nonspecific electrostatic interactions.
A peptide corresponding to the basic (+13), unstructured effector domain of myristoylated alanine-rich C kinase substrate (MARCKS) binds strongly to membranes containing phosphatidylinositol 4,5-bisphosphate (PIP(2)). Although aromatic residues contribute to the binding, three experiments suggest the binding is driven mainly by nonspecific local electrostatic interactions. First, peptides with 13 basic residues, Lys-13 and Arg-13, bind to PIP(2)-containing vesicles with the same high affinity as the effector domain peptide. Second, removing basic residues from the effector domain peptide reduces the binding energy by an amount that correlates with the number of charges removed. Third, peptides corresponding to a basic region in GAP43 and MARCKS effector domain-like regions in other proteins (e.g. MacMARCKS, adducin, Drosophila A kinase anchor protein 200, and N-methyl-d-aspartate receptor) also bind with an energy that correlates with the number of basic residues. Kinetic measurements suggest the effector domain binds to several PIP(2). Theoretical calculations show the effector domain produces a local positive potential, even when bound to a bilayer with 33% monovalent acidic lipids, and should thus sequester PIP(2) laterally. This electrostatic sequestration was observed experimentally using a phospholipase C assay. Our results are consistent with the hypothesis that MARCKS could reversibly sequester much of the PIP(2) in the plasma membrane.
Wang
Jiyao
J
Department of Physiology and Biophysics, State University of New York, Stony Brook, New York 11794-8661, USA.
Gambhir
Alok
A
Hangyás-Mihályné
Gyöngyi
G
Murray
Diana
D
Golebiewska
Urszula
U
McLaughlin
Stuart
S
D000595:Amino Acid Sequence; D001665:Binding Sites; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000737:chemistry* / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism; D055672:Static Electricity
D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D019269:Phosphatidylinositol 4,5-Diphosphate; D010750:Phosphoproteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate