Binds GTP and has low GTPase activity. May have a GTP-dependent regulatory function. GTPase activity is inhibited by metal binding. Activity is decreased in the presence of Co(II) or Ni(II), and is completely inhibited in the presence of Zn(II). kcat is 0.006 sec(-1) for GTP hydrolysis in the absence of metal. kcat is 0.0005 sec(-1) for GTP hydrolysis in the presence of Co(II). Monomer in the apo form. Metal binding induces oligomerization. Forms homodimers and higher oligomers. Belongs to the SIMIBI class G3E GTPase family. CobW subfamily.