BPS2026 – The origin of motility clarified by using a minimal synthetic bacterium, JCVI-syn3

Generally, tracing the immediate origin of cell motility from its structure is not straightforward (Miyata M et al 2020 Genes Cells). That is, we cannot find structures clearly similar to the motility machinery are not found in machineries performing unrelated roles. Surprisingly, the structures of the motility machinery in the genera Mycoplasma and Spiroplasm a, known as parasitic bacteria, closely resemble those of ATP synthase and MreB, the scaffold for peptidoglycan synthase, respectively (Toyonaga et al 2025 SciAdv adr9319, Kiyama H et al 2022 SciAdv eabo7490). To investigate the role of MreB, we focused on the minimal synthetic bacterium JCVI-syn3 (hereafter syn3) published by the Craig Venter Institute (Hutchison, C.A 3rd et al. 2016 Science , aad6253). syn3 is an organism with a genome whose genes were maximally removed from a fast-growing Mycoplasma species. When two types of MreB derived from Spiroplasma were expressed in syn3, similar helical shape and inversion-based motility observed in Spiroplasma were reproduced. These findings support a hypothesis that cell motility evolved from a protein essential for life that unexpectedly possesses movements.