[ODP-033/WS4-5] Role of seven proteins conferring Spiroplasma swimming motility to synthetic bacterium JCVI-syn3.0
Spiroplasma eriocheiris, a crustacean pathogen, exhibits unique swimming motility by shifting its cell helicity, driven by an internal ribbon structure. Generally, genus Spiroplasma can infect animal and plant tissues by this motility. In the last meeting, we reported this motility was reconstructed in a synthetic bacterium JCVI-syn3.0, by introducing seven genes encoding Fibril, five MreBs (bacterial actin), and an unannotated protein. Syn3.0 is nonmotile and has the genome composed of only essential genes from Mycoplasma mycoides. This year, we analyzed the swimming behaviors of the swimming syn3.0 in detail. The helical pitch and angle were not significantly different from those of the original Spiroplasma cells. However, the traveling of helicity shift was less processive than that of original, affecting smooth swimming. A nonsense mutation was introduced into each of the seven genes. Obvious effects on swimming were observed in strains lacking MreB5 or Fibril. The strain lacking MreB5 formed cells of short-pitch helix with only bending ‘movements’. The strain lacking Fibril formed cells of entangled helix with active helicity shifts. Interestingly, none of the mutant strains lost active movements completely, suggesting that those proteins have overlapping roles. We are analyzing other strains to elucidate the mechanism and origin of Spiroplasma swimming motility.