Single methylation of 23S rRNA triggers late steps of 50S ribosomal subunit assembly.
Ribosome biogenesis requires multiple assembly factors. In Escherichia coli, deletion of RlmE, the methyltransferase responsible for the 2'-O-methyluridine modification at position 2552 (Um2552) in helix 92 of the 23S rRNA, results in slow growth and accumulation of the 45S particle. We demonstrate that the 45S particle that accumulates in ΔrlmE is a genuine precursor that can be assembled into the 50S subunit. Indeed, 50S formation from the 45S precursor could be promoted by RlmE-mediated Um2552 formation in vitro. Ribosomal protein L36 (encoded by rpmJ) was completely absent from the 45S precursor in ΔrlmE, and we observed a strong genetic interaction between rlmE and rpmJ. Structural probing of 23S rRNA and high-salt stripping of 45S components revealed that RlmE-mediated methylation promotes interdomain interactions via the association between helices 92 and 71, stabilized by the single 2'-O-methylation of Um2552, in concert with the incorporation of L36, triggering late steps of 50S subunit assembly.
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan.
Taiga
T
Arai
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan.
Kensuke
K
Ishiguro
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan.
Satoshi
S
Kimura
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan.
Yuriko
Y
Sakaguchi
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan.
Takeo
T
Suzuki
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan ts@chembio.t.u-tokyo.ac.jp.
Tsutomu
T
Suzuki
D004926:Escherichia coli / Q000235:genetics; D008745:Methylation; D009154:Mutation; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*
D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S
L36; RlmE; post-transcriptional modification; rRNA methyltransferase; ribosome assembly