Journal Article

Structural basis of actin monomer re-charging by cyclase-associated protein

Vattulainen, Ilpo, Lappalainen, Pekka, Kotila, Tommi, Goode, Bruce L., Guo, Siyang, Enkavi, Giray, Kogan, Konstantin

2018

Overview

Actin polymerization powers key cellular processes, including motility, morphogenesis, and endocytosis. The actin turnover cycle depends critically on “re-charging” of ADP-actin monomers with ATP, but whether this reaction requires dedicated proteins in cells, and the underlying mechanism, have remained elusive. Here we report that nucleotide exchange catalyzed by the ubiquitous cytoskeletal regulator cyclase-associated protein (CAP) is critical for actin-based processes in vivo. We determine the structure of the CAP–actin complex, which reveals that nucleotide exchange occurs in a compact, sandwich-like complex formed between the dimeric actin-binding domain of CAP and two ADP-actin monomers. In the crystal structure, the C-terminal tail of CAP associates with the nucleotide-sensing region of actin, and this interaction is required for rapid re-charging of actin by both yeast and mammalian CAPs. These data uncover the conserved structural basis and biological role of protein-catalyzed re-charging of actin monomers. Depolymerized ADP-actin monomers must be recharged with ATP for new rounds of filament assembly. Here the authors show that cyclase-associated protein (CAP) catalyzes actin nucleotide exchange in vivo and their CAP–actin complex structure reveals the molecular mechanism of CAP-mediated actin nucleotide exchange.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 119/118 / 38/70 / 631/535/1266 / 631/80/128/1276 / 82/16 / 82/83 / Actin / Actin Capping Proteins - chemistry / Actin Capping Proteins - genetics / Actin Capping Proteins - metabolism / Actin Cytoskeleton - metabolism / Actin Cytoskeleton - ultrastructure / Actins - chemistry / Actins - metabolism / Adenosine diphosphate / Adenosine Diphosphate - analogs & derivatives / Adenosine Diphosphate - chemistry / Adenosine Diphosphate - metabolism / Adenosine triphosphate / Adenosine Triphosphate - chemistry / Adenosine Triphosphate - metabolism / Amino Acid Sequence / Animals / Binding Sites / Carrier Proteins - chemistry / Carrier Proteins - genetics / Carrier Proteins - metabolism / Charging / Cloning, Molecular / Crystal structure / Crystallography, X-Ray / Cytoskeleton / Endocytosis / Escherichia coli - genetics / Escherichia coli - metabolism / Gene Expression / Genetic Vectors - chemistry / Genetic Vectors - metabolism / Humanities and Social Sciences / In vivo methods and tests / Kinetics / Mice / Molecular Dynamics Simulation / Monomers / Morphogenesis / multidisciplinary / Polymerization / Protein Binding / Protein Conformation, alpha-Helical / Protein Conformation, beta-Strand / Protein Interaction Domains and Motifs / Protein Multimerization / Proteins / Recombinant Proteins - chemistry / Recombinant Proteins - genetics / Recombinant Proteins - metabolism / Saccharomyces cerevisiae - genetics / Saccharomyces cerevisiae - metabolism / Saccharomyces cerevisiae Proteins - chemistry / Saccharomyces cerevisiae Proteins - genetics / Saccharomyces cerevisiae Proteins - metabolism / Science / Science (multidisciplinary) / Sequence Alignment / Sequence Homology, Amino Acid / Yeast