182 Investigating the mode of action of an essential OBG GTPase, CgtA in bacteria

CgtA is an essential OBG GTPase (Trach & Hoch, 1989) highly conserved from bacteria to eukaryotes. It is a multifunctional protein, involved in DNA replication, chromosome partitioning (Slominska et al., 2002), nutritional stress response, initiation of sporulation, ribosome maturation, etc. Despite being a multifunctional essential protein, its mode of action is not well- characterized and key question remains: how does this protein work in wide varieties of cellular function? The expression of cgtA-mRNA increases on the onset of nutritional stress. Purified CgtA protein shows increased GTPase activity in the presence of ribosome. Our experiment with thiostrepton reveals that, although ribosome is able to trigger the GTPase activity of CgtA, its probable site of GTPase inducing activity is different from other regular translation factors like EF-G, that uses GTP. For structure function study we have generated an energy minimized homology model of the Vibrio cholerae CgtA protein, which reveals two large ...