Actin binding to the central domain of WASP/Scar proteins plays a critical role in the activation of the Arp2/3 complex
- The Arp2/3 complex nucleates and cross-links actin filaments at the leading edge of motile cells, and its activity is stimulated by C-terminal regions of WASP/Scar proteins, called VCA domains. VCA domains contain a verprolin homology sequence (V) that binds monomeric actin and central (C) and acidic sequences (A) that bind the Arp2/3 complex. Here we show that the C domain binds to monomeric actin with higher affinity (K(d) = 10 microm) than to the Arp2/3 complex (K(d) > 200 microm). Nuclear magnetic resonance spectroscopy reveals that actin binds to the N-terminal half of the C domain and that both the V and C domains can bind actin independently and simultaneously, indicating that they interact with different sites. Mutation of conserved hydrophobic residues in the actin-binding interface of the C domain disrupts activation of the Arp2/3 complex but does not alter affinity for the complex. By chemical cross-linking the C domain interacts with the p40 subunit of the Arp2/3 complex and, by fluorescence polarization anisotropy, the binding of actin and the Arp2/3 complex are mutually exclusive. Our results indicate that both actin and Arp2/3 binding are important for C domain function but that the C domain does not form a static bridge between the two. We propose a model for activation of the Arp2/3 complex in which the C domain first primes the complex by inducing a necessary conformational change and then initiates nucleus assembly by bringing an actin monomer into proximity of the primed complex.
Verfasserangaben: | Alexander E. KellyORCiD, Heather Kranitz, Volker DötschORCiDGND, R. Dyche MullinsORCiD |
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URN: | urn:nbn:de:hebis:30:3-762504 |
DOI: | https://doi.org/10.1074/jbc.M507470200 |
ISSN: | 0021-9258 |
Pubmed-Id: | https://pubmed.ncbi.nlm.nih.gov/16403731 |
Titel des übergeordneten Werkes (Englisch): | Journal of biological chemistry |
Verlag: | American Society for Biochemistry and Molecular Biology Publications |
Verlagsort: | Bethesda, Md |
Dokumentart: | Wissenschaftlicher Artikel |
Sprache: | Englisch |
Datum der Veröffentlichung (online): | 04.01.2021 |
Jahr der Erstveröffentlichung: | 2006 |
Veröffentlichende Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Datum der Freischaltung: | 22.04.2024 |
Jahrgang: | 281.2006 |
Ausgabe / Heft: | 15 |
Seitenzahl: | 9 |
Erste Seite: | 10589 |
Letzte Seite: | 10597 |
Institute: | Biochemie, Chemie und Pharmazie / Biochemie und Chemie |
DDC-Klassifikation: | 5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie |
Sammlungen: | Universitätspublikationen |
Lizenz (Deutsch): | Creative Commons - CC BY - Namensnennung 4.0 International |