One of at least 4 proteins (Era, RbfA, RimM and RsgA/YjeQ) that assist in the late maturation steps of the functional core of the 30S ribosomal subunit (PubMed:18223068, PubMed:21102555, PubMed:21303937, PubMed:25904134, PubMed:27382067). Binds the 30S subunit contacting the head, platform, and rRNA helix 44, which may assist the last maturation stages (PubMed:21788480, PubMed:21960487). Removes RbfA from mature, but not immature 30S ribosomes in a GTP-dependent manner; 95% removal in the presence of GTP, 90% removal in GMP-PNP and 65% removal in the presence of GDP (PubMed:21102555, PubMed:25904134). Circulary permuted GTPase that catalyzes rapid hydrolysis of GTP with a slow catalytic turnover (PubMed:12220175). Dispensible for viability, but important for overall fitness. The intrinsic GTPase activity is stimulated by the presence of 30S (160-fold increase in kcat) or 70S (96-fold increase in kcat) ribosomes (PubMed:14973029). Mature 30S ribosomes stimulate intrinsic GTPase more than do immature 30S ribosomes (PubMed:25904134). Ribosome-associated GTPase activity is stimulated by RbfA (PubMed:21102555). The GTPase is inhibited by aminoglycoside antibiotics such as neomycin and paromycin (PubMed:15466596) streptomycin and spectinomycin (PubMed:15828870). This inhibition is not due to competition for binding sites on the 30S or 70S ribosome (PubMed:15828870). Binds 1 zinc ion per subunit. Measured in the absence of 30S ribosomes, kcat is 8.1 h(-1) for GTP, 5.2 for dATP, 3.5 for ATP, 4.5 for ITP, 7.1 for dGTP, 2.1 for CTP. Monomer (Probable). All of the protein is associated with ribosomes; the ratio is substoichiometric at 1:200 RsgA/ribosome (PubMed:14973029). Association is tightest with the 30S subunit in the presence of the non-hydrolyzable GTP analog GMP-PNP (PubMed:14973029, PubMed:15466596). 2 cryoelectron microscopy (cryo-EM) structures in complex with 30S ribosomes have been resolved; the protein is determined to bind to different but partially overlapping regions of the 30S ribosomal subunit (PubMed:21788480, PubMed:21960487). One cryo-EM study suggests it contacts ribosomal proteins S3, S12 and S13 as well as 16S rRNA (PubMed:21788480). Another cryo-EM study shows it to bind 16S rRNA, no ribosomal proteins, and to cover the sites of intersubunit bridges B2a, B3 and B7a (PubMed:21960487). Has a significant preference for mature versus immature 30S ribosomes in the presence of GMP-PNP (PubMed:21102555, PubMed:27382067). Another study shows it binds equally well to mature and immature 30S ribosomal subunits in the presence of GMP-PNP (PubMed:25904134). Associates with 30S ribosomes (PubMed:14973029). Has 3 domains; an N-terminal OB-like domain (about residues 1-100), a central, circularly permutated GTPase module (residues 104-270) and the C-terminal zinc-finger domain (residues 280 to 350) (PubMed:25904134). The C-terminal domain has 2 regions; the zinc-binding domain (residues 287-319) is required for binding to 30S ribosomes while the extreme C-terminus (residues 320-350) helps remove RbfA from the mature 30S subunit. Reduced growth rate, reduced 70S ribosomes, accumulation of 17S rRNA (the precursor of 16S rRNA) (PubMed:15466596, PubMed:21303937, PubMed:25904134, PubMed:27382067). Ribosomal proteins S2 and S21 not found in 30S subunits, decreased S3 and RbfA in 30S subunits, distortion of rRNA helix 44 near the decoding center (PubMed:21303937, PubMed:27382067). The phenotype is partially suppressed by overexpression of a number of genes involved in ribosome function, including infB, era and ksgA (PubMed:15466596). Double rbfA-rsgA deletion mutants have the same phenotype as single mutants (PubMed:21102555). Single rgsA deletion is suppressed by a number of mutants in RbfA but not by wild-type RbfA; in all the RbfA mutants less RbfA is found bound to the 30S ribosome (PubMed:21102555). Belongs to the TRAFAC class YlqF/YawG GTPase family. RsgA subfamily. Was initially characterized with a propeptide of 20 residues; this is now thought to be the result of in vitro proteolysis when the protein is overexpressed (PubMed:12220175, PubMed:14973029). Truncated N-terminus.