Reconstitution of Contractile FtsZ Rings in Liposomes

TLDR

FtsZ, a tubulin homolog, forms the Z ring with other division proteins and drives bacterial cell constriction. The authors engineered a membrane‑anchored FtsZ (FtsZ‑mts) by fusing an amphipathic helix to its C‑terminus. In lipid vesicles, FtsZ‑mts assembled into mobile, coalescing Z rings that produced visible constrictions, demonstrating that FtsZ alone can form the Z ring and generate constriction force without additional proteins.

Abstract

FtsZ is a tubulin homolog and the major cytoskeletal protein in bacterial cell division. It assembles into the Z ring, which contains FtsZ and a dozen other division proteins, and constricts to divide the cell. We have constructed a membrane-targeted FtsZ (FtsZ-mts) by splicing an amphipathic helix to its C terminus. When mixed with lipid vesicles, FtsZ-mts was incorporated into the interior of some tubular vesicles. There it formed multiple Z rings that could move laterally in both directions along the length of the liposome and coalesce into brighter Z rings. Brighter Z rings produced visible constrictions in the liposome, suggesting that FtsZ itself can assemble the Z ring and generate a force. No other proteins were needed for assembly and force generation.