GTPase ObgE/CgtA

UniProtKB accession:  P42641

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UniProtKB description:  An abundant, essential GTPase which binds GTP, GDP and ppGpp with moderate affinity. Has high guanosine nucleotide exchange rate constants for GTP and GDP, and a relatively low GTP hydrolysis rate stimulated by the 50S ribosomal subunit. It is estimated there are 34000 molecules in log-phase cells and 5600 molecules in stationary-phase cells. Required for chromosome segregation. Plays a role in the stringent response, perhaps by sequestering 50S ribosomal subunits and decreasing protein synthesis (PubMed:19555460), and a non-essential role in the late steps of ribosome biogenesis, perhaps acting as a checkpoint for correct 50S subunit synthesis (Probable) (PubMed:24844575). Overexpression increases bacterial persistence (in exponential and stationary phase) in response to antibiotics (PubMed:26051177). Cells expressing high levels of Obg are more likely to form persister cells upon antibiotic exposure; this requires alarmone (p)ppGpp and acts via induced HokB, depolarizing cells, which probably reduces metabolic activity and induces persistence (PubMed:26051177). The persister phenotype can be separated from the essential phenotype (PubMed:26051177).