An essential GTPase that binds both GDP and GTP, with rapid nucleotide exchange. Plays a role in 16S rRNA processing and 30S ribosomal subunit biogenesis and possibly also in cell cycle regulation and energy metabolism. Monomer. More than twofold more abundant in the small cell variant (SCV) stage than in the large cell variant (LCV) stage (at protein level). LCVs are more metabolically active than SCVs. Belongs to the TRAFAC class TrmE-Era-EngA-EngB-Septin-like GTPase superfamily. Era GTPase family.