7O5H

Ribosomal methyltransferase KsgA bound to small ribosomal subunit

Summary for 7O5H

• Entry DOI: 10.2210/pdb7o5h/pdb
• EMDB information: 12736
• Descriptor: Ribosomal RNA small subunit methyltransferase A, 30S ribosomal protein S15, 30S ribosomal protein S16, ... (16 entities in total)
• Functional Keywords: methyltransferase ksga, 30s, ribosome
• Biological source: Escherichia coli (strain K12); More
• Total number of polymer chains: 15
• Total formula weight: 513915.31

Authors

Stephan, N.C.,Ries, A.B.,Boehringer, D.,Ban, N. (deposition date: 2021-04-08, release date: 2021-06-16, Last modification date: 2024-07-10)

Primary citation

Stephan, N.C.,Ries, A.B.,Boehringer, D.,Ban, N.
Structural basis of successive adenosine modifications by the conserved ribosomal methyltransferase KsgA.
Nucleic Acids Res., 49:6389-6398, 2021

PubMed Abstract: Biogenesis of ribosomal subunits involves enzymatic modifications of rRNA that fine-tune functionally important regions. The universally conserved prokaryotic dimethyltransferase KsgA sequentially modifies two universally conserved adenosine residues in helix 45 of the small ribosomal subunit rRNA, which is in proximity of the decoding site. Here we present the cryo-EM structure of Escherichia coli KsgA bound to an E. coli 30S at a resolution of 3.1 Å. The high-resolution structure reveals how KsgA recognizes immature rRNA and binds helix 45 in a conformation where one of the substrate nucleotides is flipped-out into the active site. We suggest that successive processing of two adjacent nucleotides involves base-flipping of the rRNA, which allows modification of the second substrate nucleotide without dissociation of the enzyme. Since KsgA is homologous to the essential eukaryotic methyltransferase Dim1 involved in 40S maturation, these results have also implications for understanding eukaryotic ribosome maturation.

PubMed: 34086932
DOI: 10.1093/nar/gkab430

Experimental method

ELECTRON MICROSCOPY (3.1 Å)