(a, b) Fluorescence, phase contrast, and merged images demonstrating localization of fluorescent fusions to divisome proteins in cells producing ΔCTL. MurG-mCherry and mCherry-FtsI were produced upon vanillate induction in the EG937 background. Cells were grown in the presence of glucose or xylose for 8.5 h prior to imaging. Vanillate was added 2 h prior to imaging to induce expression of the fluorescent fusion. (c) Graphical representation of the role of FtsZ in promoting PG remodeling in C. crescentus. (i) Once established at the incipient division site, the Z-ring promotes local assembly of the divisome, including PG enzymes and their regulators. (ii) We propose that, in addition to recruiting PG enzymes to midcell, the Z-ring initiates a signal that regulates their activity, allowing appropriate re-shaping and invagination of the cell envelope. (iii) The Z-ring turns over, making constriction an iterative process. (d) When ΔCTL is produced, midcell proteins are still recruited (i), but their activities are misregulated (ii), leading to reduced PG crosslinking, increased glycan strand length, envelope bulging, and cell lysis (iii).