FtsZ of wall-less bacteria forms ring-like structures

The FtsZ protein is involved in bacterial cell division. In cell-walled bacteria, such asBacillus subtilis, FtsZ forms a ring-like structure, called the Z ring, at the cell division site and acts as a scaffold for cell wall synthesis. The inhibition of cell wall synthesis inB. subtilishas been shown to interfere with the function of the Z ring, causing a loss in cell division control.Spiroplasma, a cell wall-less bacterium, lacks most of the genes involved in cell division; however, theftsZgene remains conserved. The function ofSpiroplasma eriocheirisFtsZ (SeFtsZ) remains to be determined. In the present study, we analyzed the biochemical characteristics of SeFtsZ. Purified SeFtsZ demonstrated lower polymerization capacity and GTPase activity than FtsZ fromE. coliandB. subtilis. We also investigated the relationship between SeFtsZ and SeSepF, which anchors FtsZ to the cell membrane, and found that SeSepF did not contribute to the stability of FtsZ filaments, unlike theB. subtilisSepF. SeFtsZ and SeSepF were produced inE. coliL-forms, where cell wall synthesis was inhibited. SeFtsZ formed ring-like structures in cell wall-lessE. colicells, suggesting that SeFtsZ forms Z rings and is involved in cell division independently of cell wall synthesis.