title: Formation of an actin-like filament concurrent with the enzymatic synthesis of inorganic polyphosphate.
abstract: Inorganic polyphosphate (poly P), a chain of hundreds of phosphate residues linked by ATP-like bonds, is found in every cell in nature and is commonly produced from ATP by poly P kinases (e.g., PPK1). Dictyostelium discoideum, the social slime mold, possesses a PPK activity (DdPPK1) with sequence similarity to bacterial PPKs. We find here a previously unrecognized PPK (DdPPK2) in D. discoideum with the sequences and properties of actin-related proteins (Arps) that are similar to muscle actins in size, properties, and globular-filamentous structural transitions. Significantly, the unique actin inhibitors, phalloidin and DNase I, also inhibit synthesis of poly P by DdPPK2. Thus, this particular Arp complex is an enzyme that can polymerize into an actin-like filament concurrent with its synthesis of a poly P chain in a fully reversible reaction.
authors.affiliation: Department of Biochemistry, Stanford University School of Medicine, 279 Campus Drive West, Stanford, CA 94305-5307, USA.
authors.forename: María R
authors.initials: MR
authors.lastname: Gómez-García
authors.forename: Arthur
authors.initials: A
authors.lastname: Kornberg
mesh_terms: D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003850:Deoxyribonuclease I / Q000494:pharmacology; D004023:Dictyostelium / Q000201:enzymology; D004734:Energy Metabolism; D006868:Hydrolysis; D007700:Kinetics; D008854:Microscopy, Electron; D010590:Phalloidine / Q000494:pharmacology; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism*
chemical_list: D000199:Actins; D011122:Polyphosphates; D010590:Phalloidine; D000255:Adenosine Triphosphate; D017856:Phosphotransferases (Phosphate Group Acceptor); C022424:polyphosphate kinase; D003850:Deoxyribonuclease I