title: Structural insights into the inhibition of actin-capping protein by interactions with phosphatidic acid and phosphatidylinositol (4,5)-bisphosphate.
abstract: The actin cytoskeleton is a dynamic structure that coordinates numerous fundamental processes in eukaryotic cells. Dozens of actin-binding proteins are known to be involved in the regulation of actin filament organization or turnover and many of these are stimulus-response regulators of phospholipid signaling. One of these proteins is the heterodimeric actin-capping protein (CP) which binds the barbed end of actin filaments with high affinity and inhibits both addition and loss of actin monomers at this end. The ability of CP to bind filaments is regulated by signaling phospholipids, which inhibit the activity of CP; however, the exact mechanism of this regulation and the residues on CP responsible for lipid interactions is not fully resolved. Here, we focus on the interaction of CP with two signaling phospholipids, phosphatidic acid (PA) and phosphatidylinositol (4,5)-bisphosphate (PIP(2)). Using different methods of computational biology such as homology modeling, molecular docking and coarse-grained molecular dynamics, we uncovered specific modes of high affinity interaction between membranes containing PA/phosphatidylcholine (PC) and plant CP, as well as between PIP(2)/PC and animal CP. In particular, we identified differences in the binding of membrane lipids by animal and plant CP, explaining previously published experimental results. Furthermore, we pinpoint the critical importance of the C-terminal part of plant CPα subunit for CP-membrane interactions. We prepared a GST-fusion protein for the C-terminal domain of plant α subunit and verified this hypothesis with lipid-binding assays in vitro.
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Roman
authors.initials: R
authors.lastname: Pleskot
authors.forename: Přemysl
authors.initials: P
authors.lastname: Pejchar
authors.forename: Viktor
authors.initials: V
authors.lastname: Žárský
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Staiger
authors.forename: Martin
authors.initials: M
authors.lastname: Potocký
mesh_terms: D051344:Actin Capping Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D030161:Avian Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002645:Chickens; D019295:Computational Biology; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010712:Phosphatidic Acids / Q000737:chemistry / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000737:chemistry / Q000378:metabolism*; D010802:Phylogeny; D011485:Protein Binding; D016415:Sequence Alignment; D013329:Structure-Activity Relationship
chemical_list: D051344:Actin Capping Proteins; D029681:Arabidopsis Proteins; D030161:Avian Proteins; D010712:Phosphatidic Acids; D018129:Phosphatidylinositol Phosphates