Cell wall synthesis and remodeling dynamics determine bacterial division site architecture and cell shape

The bacterial division apparatus builds daughter cell poles by catalyzing the synthesis and remodeling of the septal peptidoglycan (sPG) cell wall. Understanding of this essential process has been limited by the lack of native three-dimensional visualization of developing septa. Here, we used state-of-the-art cryogenic electron tomography (cryo-ET) and fluorescence microscopy to understand the division site architecture and sPG biogenesis dynamics of the Gram-negative bacterium Escherichia coli. Our results with mutant cells altered in the regulation of sPG biogenesis revealed a striking and unexpected similarity between the architecture of E. coli septa with those from Gram-positive bacteria, suggesting a conserved morphogenic mechanism. Furthermore, we found that the cell elongation and division machineries are in competition and that their relative activities determine the shape of cell constrictions and the poles they form. Overall, our results highlight how the activity of the division system can be modulated to generate the diverse array of morphologies observed in the bacterial domain. HighlightsO_LIThe division site architecture of E. coli can be modulated to resemble that of diverse bacteria. C_LIO_LICell wall degradation at the division site activates septal cell wall synthesis. C_LIO_LIAssembly of the cytoskeletal ring at the division site is modulated by cell wall remodeling. C_LIO_LIBalance between the activities of the elongation and division systems modulates cell shape. C_LI