Crystal Structure of Arp2/3 Complex

• Published in: Science (American Association for the Advancement of Science) 2001-11, Vol.294 (5547), p.1679-1684
• Main Authors: Robinson, Robert C., Turbedsky, Kirsi, Kaiser, Donald A., Marchand, Jean-Baptiste, Higgs, Henry N., Choe, Senyon, Pollard, Thomas D.
• Format: Article
• Language: English
• Subjects: Actin; Actin Cytoskeleton - chemistry; Actin Cytoskeleton - metabolism; Actin-Related Protein 2; Actin-Related Protein 3; Actins; Actins - chemistry; Actins - metabolism; Adenosine Triphosphate - metabolism; Animals; Biological and medical sciences; Cattle; Cells; Cells (Biology); Crystal structure; Crystallography, X-Ray; Crystals; Cytoskeletal Proteins; Dimers; Electron density; Eukaryotes; Eukaryotic cells; Fundamental and applied biological sciences. Psychology; Genetic research; Inhalants; Macromolecular Substances; Microfilaments; Models, Biological; Models, Molecular; Molecular and cellular biology; Muscle, Skeletal; Nucleation; Nucleotides; Polymers; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Structure, Tertiary; Protein Subunits; Proteins; Research Article; Static Electricity; Thymus Gland; Ungulates
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1066333

We determined a crystal structure of bovine Arp2/3 complex, an assembly of seven proteins that initiates actin polymerization in eukaryotic cells, at 2.0 angstrom resolution. Actin-related protein 2 (Arp2) and Arp3 are folded like actin, with distinctive surface features. Subunits ARPC2 p34 and ARPC4 p20 in the core of the complex associate through long carboxyl-terminal α helices and have similarly folded amino-terminal α/β domains. ARPC1 p40 is a seven-blade β propeller with an insertion that may associate with the side of an actin filament. ARPC3 p21 and ARPC5 p16 are globular α-helical subunits. We predict that WASp/Scar proteins activate Arp2/3 complex by bringing Arp2 into proximity with Arp3 for nucleation of a branch on the side of a preexisting actin filament.