| Understanding the molecular basis of bacterial cell morphogenesis is by and large far from complete. In my studies, I have attempted to search for novel determinants of cell morphology that may provide important insights into the way cells regulate growth and subsequently morphology. Using a genetic screen approach, I searched for mutants with aberrant cell shape. One mutant was isolated with defects at every level of morphogenesis control. The gene mutated was renamed rodZ, a novel gene that is conserved across the bacterial kingdom. I show that RodZ is an important growth determinant in both Caulobacter crescentus and Escherichia coli, by localizing to areas where active peptidoglycan growth is known to occur. In both these organisms, RodZ functions by interacting with the MreB actin homolog, which has been postulated to regulate growth of the peptidoglycan cell wall. Consistent with an important function within the cell, rodZ is essential for viability in C. crescentus. To gain additional insights into RodZ's mechanism of function, I studied the interaction between RodZ and the isoprenoid biosynthesis pathway. Genomic evidence suggests that rodZ and gcpE, a gene involved in the isoprenoid biosynthesis pathway, have closely segregated together throughout evolution. In my studies, I show that the phenotype of the DeltarodZ mutant cannot, by itself, be attributed to a deficiency of isoprenoids within the cell. An interaction between RodZ and GcpE should not however be excluded and will be the basis of future studies to elucidate the role of RodZ in cytoskeleton-based morphogenesis. |
