Abstract
Obg is an essential, conserved G-protein that has been implicated in chromosome partitioning, DNA replication regulation, the stringent response, and linking cell cycle events with translational capacity. How Obg carries out all of these varied functions is currently unknown. When ObgE, the Escherichia coli homologue of Obg, is depleted, E. coli displays various growth defects including errors in chromosome partitioning and cytokinesis, causing the formation of long filamentous cells with large DNA contents. Preliminary results suggest that in wild-type cells, ObgE localizes to the membrane and midcell. Deletion of the N-terminus disrupts this localization and these cells improperly segregate their chromosomes. We propose that the N-terminus of ObgE is responsible for its localization to midcell and the membrane. We used site directed mutagenesis of the N-terminus to mutate a conserved basic N terminal residue to alanine. We analyzed the localization of ObgE, number of nucleoids, and total cellular DNA content in cells expressing this mutant ObgE. In addition, we investigated the ability of these cells to survive UV exposure. The data presented here supports the theory that ObgE monitors DNA replication and regulates DNA partitioning. Further analysis of this mutant will advance our understanding of the function of ObgE and its role in the process of DNA segregation.