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Capreomycin susceptibility is increased by TlyA‐directed 2′‐ O ‐methylation on both ribosomal subunits
Author(s) -
Monshupanee Tanakarn,
Johansen Shanna K.,
Dahlberg Albert E.,
Douthwaite Stephen
Publication year - 2012
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2012.08168.x
Subject(s) - capreomycin , viomycin , biology , ribosomal rna , ribosome , biochemistry , 23s ribosomal rna , nucleotide , methylation , transfer rna , rna , antibiotics , streptomycin , dna , gene , ethambutol
Summary The binding site of the cyclic peptide antibiotics capreomycin and viomycin is located on the ribosomal subunit interface close to nucleotides C1409 in 16S rRNA and C1920 in 23S rRNA. In Mycobacterium tuberculosis, the 2′‐hydroxyls of both nucleotides are methylated by the enzyme TlyA. Loss of these methylations through inactivation of TlyA confers resistance to capreomycin and viomycin. We report here that TlyA orthologues occur in diverse bacteria and fall into two distinct groups. One group, now termed TlyA I , has shorter N‐ and C‐termini and methylates only C1920; the second group (now TlyA II ) includes the mycobacterial enzyme, and these longer orthologues methylate at both C1409 and C1920. Ribosomal subunits are the preferred substrates for both groups of orthologues. Amino acid substitutions at the N‐terminus of TlyA II reduce its ability to methylate these substrates. Growing pairs of recombinant TlyA II Escherichia coli strains in competition shows that even subtle changes in the level of rRNA methylation lead to significant differences in susceptibility to sub‐inhibitory concentrations of capreomycin. The findings reveal that 2′‐ O ‐methyls at both C1409 and C1920 play a role in facilitating the inhibitory effects of capreomycin and viomycin on the bacterial ribosome.