Cell division protein that may be involved in stabilizing or promoting the assembly of the division complex. Plays an essential role in division at high temperatures, maybe by protecting FtsL from degradation or by promoting formation of the FtsL-DivIC complex. May modulate the transpeptidase activity of PBP-2B. Also required for efficient sporulation at all temperatures. Could be directly involved in the engulfment process or be required to form a sporulation septum competent for engulfment. Influences the Spo0J/Soj system of chromosome segregation. Interacts with FtsL, DivIC and PBP-2B. Localizes to the division septum. Localization requires FtsZ and DivIC. Localization of DivIB and DivIC is codependent at high temperatures. The extracellular region contains three distinct subdomains: a membrane proximal alpha domain, a central beta domain and an unstructured C-terminal gamma domain. The C-terminal region of the beta domain is critical for interaction with PBP-2B. Contains multiple septal localization epitopes that are located within the transmembrane region and within the extracellular region. These epitopes may represent sites of interaction with other divisomal proteins. Mutants show a drastic decrease in sporulation efficiency. Polar septation is delayed and less efficient, and the completed septa are thicker than those of the wild type. Mutants are also unable to undergo engulfment. Belongs to the FtsQ/DivIB family. DivIB subfamily.