Format

Send to

Choose Destination
Proc Natl Acad Sci U S A. 2015 Nov 24;112(47):E6436-45. doi: 10.1073/pnas.1510876112. Epub 2015 Nov 9.

Allosteric N-WASP activation by an inter-SH3 domain linker in Nck.

Author information

1
Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158; The Howard Hughes Medical Institute Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543;
2
Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158;
3
Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390;
4
Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158.
5
Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158; The Howard Hughes Medical Institute Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543; jack.taunton@ucsf.edu.

Abstract

Actin filament networks assemble on cellular membranes in response to signals that locally activate neural Wiskott-Aldrich-syndrome protein (N-WASP) and the Arp2/3 complex. An inactive conformation of N-WASP is stabilized by intramolecular contacts between the GTPase binding domain (GBD) and the C helix of the verprolin-homology, connector-helix, acidic motif (VCA) segment. Multiple SH3 domain-containing adapter proteins can bind and possibly activate N-WASP, but it remains unclear how such binding events relieve autoinhibition to unmask the VCA segment and activate the Arp2/3 complex. Here, we have used purified components to reconstitute a signaling cascade driven by membrane-localized Src homology 3 (SH3) adapters and N-WASP, resulting in the assembly of dynamic actin networks. Among six SH3 adapters tested, Nck was the most potent activator of N-WASP-driven actin assembly. We identify within Nck a previously unrecognized activation motif in a linker between the first two SH3 domains. This linker sequence, reminiscent of bacterial virulence factors, directly engages the N-WASP GBD and competes with VCA binding. Our results suggest that animals, like pathogenic bacteria, have evolved peptide motifs that allosterically activate N-WASP, leading to localized actin nucleation on cellular membranes.

KEYWORDS:

N-WASP; Nck; SH3 adapter; actin cytoskeleton; signal transduction

PMID:
26554011
PMCID:
PMC4664294
DOI:
10.1073/pnas.1510876112
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center