Recombinant Bacillus subtilis GTPase obgE (obg)

Necessary for the transition from vegetative growth to stage 0 or stage II of sporulation, but sporulation subsequent to these stages is unaffected at 45 degrees Celsius. This ts effect is probably due solely to the E-79 mutation. Required for expression of early sporulation genes, further suggesting a role in the induction of sporulation. Depletion effects on sporulation can be partially suppressed by missense mutations in spo0A. Strains depleted for obg stop growing after about 3 hours and do not induce the sigma-B factor following ethanol stress. It cofractionates with the ribosome and upstream stress response regulators RsbR, RsbS and RsbT in size fractionation columns, suggesting the ribosome might serve as a possible mediator of the activity of obg and the stress induction of sigma-B. In glycerol gradients partially associates with ribosomes; this is stabilized by a nonhydrolyzable GTP-analog and to a lesser extent GTP and GDP.; An essential GTPase which binds GTP, GDP and possibly (p)ppGpp with moderate affinity, with high nucleotide exchange rates and a fairly low GTP hydrolysis rate. Plays a role in control of the cell cycle, stress response, ribosome biogenesis and in those bacteria that undergo differentiation, in morphogenesis control.