An essential GTPase (4.1 pmol GTP/min) (PubMed:21195156). Cannot substitute endogenous obg in E.coli, has a partially dominant-negative phenotype upon overexpression in liquid culture leading to decreased growth rate in a concentration-dependent fashion, with 50% of cells being elongated (PubMed:21195156). Binds GTP, GDP and possibly (p)ppGpp with moderate affinity, with high nucleotide exchange rates and a fairly low GTP hydrolysis rate. It may play a role in control of the cell cycle, stress response, ribosome biogenesis and in those bacteria that undergo differentiation, in morphogenesis control (By similarity). Monomer. Associates with 50S ribosomal subunit upon overexpression in E.coli. Belongs to the TRAFAC class OBG-HflX-like GTPase superfamily. OBG GTPase family.