8GHU

Methyltransferase RmtC bound to the 30S ribosomal subunit

Summary for 8GHU

• Entry DOI: 10.2210/pdb8ghu/pdb
• EMDB information: 40051
• Descriptor: 16S rRNA (guanine(1405)-N(7))-methyltransferase, 30S ribosomal protein S13, 30S ribosomal protein S15, ... (16 entities in total)
• Functional Keywords: ribosome, 30s, rmtc, 16s rrna methyltransferase
• Biological source: Escherichia coli; More
• Total number of polymer chains: 15
• Total formula weight: 704543.93

Authors

Srinivas, P.,Conn, G.L.,Dunham, C.M. (deposition date: 2023-03-12, release date: 2023-04-12, Last modification date: 2024-06-19)

Primary citation

Srinivas, P.,Nosrati, M.,Zelinskaya, N.,Dey, D.,Comstock, L.R.,Dunham, C.M.,Conn, G.L.
30S subunit recognition and G1405 modification by the aminoglycoside-resistance 16S ribosomal RNA methyltransferase RmtC.
Biorxiv, 2023

PubMed Abstract: Acquired ribosomal RNA (rRNA) methylation has emerged as a significant mechanism of aminoglycoside resistance in pathogenic bacterial infections. Modification of a single nucleotide in the ribosome decoding center by the aminoglycoside-resistance 16S rRNA (m G1405) methyltransferases effectively blocks the action of all 4,6-deoxystreptamine ring-containing aminoglycosides, including the latest generation of drugs. To define the molecular basis of 30S subunit recognition and G1405 modification by these enzymes, we used a S-adenosyl-L-methionine (SAM) analog to trap the complex in a post-catalytic state to enable determination of an overall 3.0 Ã… cryo-electron microscopy structure of the m G1405 methyltransferase RmtC bound to the mature Escherichia coli 30S ribosomal subunit. This structure, together with functional analyses of RmtC variants, identifies the RmtC N-terminal domain as critical for recognition and docking of the enzyme on a conserved 16S rRNA tertiary surface adjacent to G1405 in 16S rRNA helix 44 (h44). To access the G1405 N7 position for modification, a collection of residues across one surface of RmtC, including a loop that undergoes a disorder to order transition upon 30S subunit binding, induces significant distortion of h44. This distortion flips G1405 into the enzyme active site where it is positioned for modification by two almost universally conserved RmtC residues. These studies expand our understanding of ribosome recognition by rRNA modification enzymes and present a more complete structural basis for future development of strategies to inhibit m G1405 modification to re-sensitize bacterial pathogens to aminoglycosides.

PubMed: 36993224
DOI: 10.1101/2023.03.13.532395

Experimental method

ELECTRON MICROSCOPY (3 Å)