Purification and architecture of the ubiquitous Wave complex

TLDR

Wave proteins, especially the ubiquitous Wave‑2, are key activators of the Arp2/3 complex and essential for actin polymerization at the leading edge of migrating cells. The authors purified Wave‑2 from HeLa cells, reconstituted the five‑subunit complex by cotranslating Sra, Nap, Wave‑2, Abi, and Hspc in vitro, and employed specific immunoprecipitations to dissect its molecular architecture. The purified complex consists of a tight Nap–Abi core with Sra recruited on the Nap side and Wave‑2 and Hspc on the Abi side, while Hspc also exists in a free pool.

Abstract

The Wave proteins are major activators of the Arp2/3 complex. The ubiquitous Wave-2 is required for actin polymerization at the leading edge of migrating cells. Here we purify Wave-2 from HeLa cells. Five proteins, Sra, Nap, Wave-2, Abi, and Hspc, are copurified, indicating that they form a tight complex. These proteins are only present in the complexed form, with the exception of Hspc, which displays a free pool. We reconstitute the Wave-2 complex by cotranslating in vitro the five subunits and use this system together with specific immunoprecipitations to study the molecular architecture of the complex. The complex is organized around a core of Nap and Abi. Sra is a peripheral subunit recruited on the Nap side, whereas the Wave and Hspc subunits are recruited on the Abi side of the core.