GTPase ObgE/CgtA - P42641 (OBG_ECOLI)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for P42641: 2
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). UniProt
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Subunit Structure
Monomer. Binds to the intersubunit face of the 50S ribosomal subunit where translation factors bind, protruding into the peptidyl-transfer center, leading to significant changes in both ObgE and 50S ribosome structure (PubMed:24844575). Associates with SpoT (PubMed:15292126, PubMed:17616600). Binding to 50S ribosomes does not require SpoT. 50S ribosomal subunit binding is enhanced by guanosine nucleotides (PubMed:24844575). UniProt
The C-terminus (residues 341-390) is not required for either 50S ribosome subunit association nor 70S ribosome dissociation. UniProt
  • Other Gene names: obgE, cgtA, obg, yhbZ, b3183, JW3150
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