Tissue-like structures formed by a bacterium

Abstract

Bacteria generally form only simple multicellular structures lacking the stable cell-cell connections characteristic of eukaryotic tissues. However, when the antibiotic moenomycin modifies peptidoglycan cell wall synthesis, rod-shaped cells of the Gram-negative bacterium Myxococcus xanthus become spherical, fuse their outer membranes, and assemble into stable, honeycomb-like lattices resembling eukaryotic tissues. These findings raise the intriguing possibility that some tissue-like organization could have evolved from stress-induced responses in bacterial ancestors.

Fig. 1.. M. xanthus cells form tissue-like structures under moenomycin stress.

(a) Wild-type vegetative cells are rod-shaped. (b, c) After moenomycin treatment (4 μg/ml, 4 h), cells transform into spheres and form honeycomb-like lattices of different sizes through visible cell-cell connections. (d) Cells overexpressing Pal lysed frequently and did not form tissue-like structures after moenomycin treatment. Scale bars, 5 μm.

Fig. 2.. Cells in the tissue-like structures connect to each other through extensive OM fusion.

Cells share their OMs but not cytoplasms. The cytoplasm, PG, and OM were labeled with calcein, TADA, and WGA, respectively. BF, bright field. Arrows point to the intracellular OM connections. Scale bars, 5 μm. The cartoon inset depicts the cell sections imaged using HILO illumination.