Septal wall synthesis is sufficient to change ameba-like cells into uniform oval-shaped cells in Escherichia coli L-forms.

A cell wall is required to control cell shape and size to maintain growth and division. However, some bacterial species maintain their morphology and size without a cell wall, calling into question the importance of the cell wall to maintain shape and size. It has been very difficult to examine the dispensability of cell wall synthesis in rod-shaped bacteria such as Escherichia coli for maintenance of their shape and size because they lyse without cell walls under normal culture conditions.

Evidence for biomolecular condensates of MatP in spatiotemporal regulation of the bacterial cell division cycle.

An increasing number of proteins involved in bacterial cell cycle events have been recently shown to undergo phase separation. The resulting biomolecular condensates play an important role in cell cycle protein function and may be involved in development of persister cells tolerant to antibiotics. Here we report that the chromosomal Ter macrodomain organizer MatP, a division site selection protein implicated in the coordination of chromosome segregation with cell division, forms biomolecular condensates in cytomimetic systems.

Role of the antiparallel double-stranded filament form of FtsA in activating the divisome.

The actin-like FtsA protein is essential for function of the cell division machinery, or divisome, in many bacteria including . Previous studies demonstrated that purified wild-type FtsA assembles into closed mini-rings on lipid membranes, but oligomeric variants of FtsA such as FtsA and FtsA can bypass certain divisome defects and form arc and double-stranded (DS) oligomeric states, respectively, which may reflect conversion of an inactive to an active form of FtsA. However, it remains unproven which oligomeric forms of FtsA are responsible for assembling and activating the divisome.

Role of the antiparallel double-stranded filament form of FtsA in activating the divisome.

The actin-like FtsA protein is essential for function of the cell division machinery, or divisome, in many bacteria including . Previous studies demonstrated that purified wild-type FtsA assembles into closed mini-rings on lipid membranes, but oligomeric variants of FtsA such as FtsA and FtsA can bypass certain divisome defects and form arc and double-stranded (DS) oligomeric states, respectively, which may reflect conversion of an inactive to an active form of FtsA. Yet, it remains unproven which oligomeric forms of FtsA are responsible for assembling and activating the divisome.

Macromolecular Crowding, Phase Separation, and Homeostasis in the Orchestration of Bacterial Cellular Functions.

Macromolecular crowding affects the activity of proteins and functional macromolecular complexes in all cells, including bacteria. Crowding, together with physicochemical parameters such as pH, ionic strength, and the energy status, influences the structure of the cytoplasm and thereby indirectly macromolecular function. Notably, crowding also promotes the formation of biomolecular condensates by phase separation, initially identified in eukaryotic cells but more recently discovered to play key functions in bacteria.