PT  - JOURNAL ARTICLE
AU  - Diego A. Ramirez-Diaz
AU  - Adrian Merino-Salomon
AU  - Michael Heymann
AU  - Petra Schwille
TI  - Bidirectional FtsZ filament treadmilling promotes membrane constriction via torsional stress
AID  - 10.1101/587790
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 587790
4099  - http://biorxiv.org/content/early/2019/03/24/587790.short
4100  - http://biorxiv.org/content/early/2019/03/24/587790.full
AB  - FtsZ is a key component in bacterial cell division, being the primary protein of the presumably contractile Z ring. Reconstituted in vitro, it shows two distinctive features that could so far however not be mechanistically linked: self-organization into directionally treadmilling vortices on solid supported membranes, and shape deformation of flexible liposomes. In cells, circumferential treadmilling of FtsZ was shown to recruit septum-building enzymes, but an active force production remains elusive. To determine direct contributions of FtsZ to membrane constriction, we designed a novel in vitro assay based on soft lipid tubes pulled from FtsZ decorated giant lipid vesicles (GUVs) by optical tweezers. FtsZ actively transformed these tubes into spring-like structures, where GTPase activity promoted spring compression. Operating the optical tweezers in lateral vibration mode and assigning spring constants to FtsZ coated tubes, we found that that FtsZ indeed exerts pN forces upon GTP hydrolysis, through torsional stress induced by bidirectional treadmilling.