rsgA, Small ribosomal subunit biogenesis GTPase RsgA
Enzyme Classification 3.6.1.-
Also Known as
RSGA_ECOLI, rsgA, engC, yjeQ
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). 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).