Studying the universal process of cell division in the model organism, E. coli

Septum placement and the subsequent separation into daughter cells is a major event in cell division. In E. coli, the protein FtsZ polymerizes into the septum (Z-Ring) in the middle of the cell. It is spatially oriented by two regulatory systems, the Min System (prevents assembly at poles) and Nucleoid Occlusion (prevents nucleoid guillotining). Without these systems, the cell cannot place its septum correctly. This work examines a mutant strain of E. coli that divides aberrantly despite it having these regulatory systems.

Deleting the peptidase component of the protease ClpXP and inactivating the repressor of the SOS response, lexA creates an interesting phenotype. Cells are either very long with bumps along their length or are mini cells. RecN, a protein implicated to play a role in double-strand break repair, has been identified as a suppressor of this phenotype, implicating a novel role for the protein in cell division. Overproduction of RecN in conjunction with a clpP deletion is sufficient to produce the phenotype of interest. RecN overproduction could be blocking the action of proteins such as MinD from binding and segregating the nucleoid. Utilizing fluorescent microscopy, analysis of nucleoid structure and Z-Ring placement will provide clues to the mechanisms of action in this system.