Methylation of 23S rRNA G748 and the ribosomal protein L22 Lys-94 are critical factors for maintaining the association between ribosome stalling and proteome composition in Streptococcus pneumoniae

Background23S rRNA modification located at the nascent peptides exit tunnel plays an important role in both translation processes and the binding of the antibiotics. Methylation of the guanine at position 748 (m1G748) in 23S rRNA in Streptococcus pneumoniae is involved in the ribosome stalling and the binding of the antibiotic telithromycin (TEL). The disruption of the gene encoding RlmAII which methylates 23S rRNA G748 results in the increased resistance of TEL in S. pneumoniae. However, an isolated high-level TEL-resistant S. pneumoniae strain indicated that additional undescribed factors were involved in TEL resistance in S. pneumoniae. ResultsWe successfully isolated a high-level TEL-resistant S. pneumoniae RlmAII mutant and determined the whole-genome sequence. The lysine residue at the position 94 in ribosomal protein 22 (L22 K94) was critical in binding of TEL to the ribosome. A growth competition assay showed that L22 K94 was required for the function of m1G748. Ribosome profiling revealed that m1G748 and L22 K94 were both essential to maintain the relationship between the ribosome stalling and proteome composition. ConclusionIn S. pneumoniae, the combination of methylation status of G748 and the residue at position 94 in L22 are essential for both the distribution of ribosome stalling and the binding of TEL to ribosomes.