GTPase that plays an essential role in the late steps of ribosome biogenesis. Cofractionates with the 70S ribosome; association is stabilized by the non-hydrolyzable GTP analog GMPPNP, and inhibited by GTP or GDP. Essential for growth, it cannot be disrupted. Depletion experiments show that cells become longer and abnormally curved, with nucleoid condensation. Cells have many fewer 70S ribosomes; the large ribosomal subunit is 45S and is missing proteins L16, L27, L36 and interacts with 2 large non-ribosomal proteins. Estimated to be present at 7000 copies per cell. Belongs to the TRAFAC class TrmE-Era-EngA-EngB-Septin-like GTPase superfamily. EngA (Der) GTPase family.