EC Number   |
General Information |
Reference |
|---|
  2.1.1.227 | evolution |
TlyA orthologues occur in diverse bacteria and fall into two distinct groups. One group, termed TlyAI, has shorter N- and C-termini and methylates only C1920. The second group, TlyAII, includes the mycobacterial enzyme, and these longer orthologues methylate at both C1409 and C1920 (c.f. EC 2.1.1.226) |
-, 720503 |
| 2.1.1.227 | malfunction |
disruption of the tlyA ORF can confer capreomycin resistance |
710879 |
| 2.1.1.227 | malfunction |
inactivation of TlyA and loss of its activity confer resistance to capreomycin and viomycin |
-, 720503 |
| 2.1.1.227 | malfunction |
loss-of-function mutations in rRNA methylase TlyA or point mutations in 16S rRNA, in particular the A1408G mutation. Both of these alterations result in resistance by reducing drug binding to the ribosome. Alterations of tlyA gene expression affect both antibiotic drug susceptibility and fitness cost of drug resistance. In particular, the common resistance mutation A1408G is accompanied by a physiological change that involves increased expression of the tlyA gene. This gene encodes an enzyme that methylates neighboring 16S rRNA position C1409, and as a result of increased TlyA expression the fitness cost of the A1408G mutation is significantly reduced |
-, 758323 |
| 2.1.1.227 | malfunction |
the bifunctional enzyme modifies nucleotide C1409 in helix 44 of 16S rRNA and nucleotide C1920 in helix 69 of 23S rRNA. Loss of these rRNA methylations confers resistance to capreomycin and viomycin |
713026 |
| 2.1.1.227 | metabolism |
antibiotic resistance mechanisms frequently confer a fitness cost, and these costs can be genetically ameliorated by intra- or extragenic second-site mutations, often without loss of resistance. Another mechanism by which the fitness cost of antibiotic resistance can be reduced is via a regulatory response where the deleterious effect of the resistance mechanism is lowered by a physiological alteration that buffers the mutational effect. In mycobacteria, resistance to the clinically used tuberactinomycin antibiotic capreomycin involves loss-of-function mutations in rRNA methylase TlyA or point mutations in 16S rRNA, in particular the A1408G mutation. Both of these alterations result in resistance by reducing drug binding to the ribosome. In mycobacteria, this nonmutational mechanism (i.e. gene regulatory) can restore fitness to genetically resistant bacteria. Incubation with capreomycin during bacterial growth results in a reduced post-transcriptional modification of rRNA at TlyA-dependent sites (1409 in 16S and 1920 in 23S), cf. EC 2.1.1.226 |
758323 |
| 2.1.1.227 | more |
the cyclic peptide antibiotics capreomycin and viomycin bind on the ribosomal S70 subunit interface close to nucleotides C1409 in 16S rRNA and C1920 in 23S rRNA |
720503 |
| 2.1.1.227 | physiological function |
bacterial 2'-O-methyltransferase TlyA methylates either both nucleotide C1409 of 16S rRNA and C1920 of 23S rRNA. Both ribosomal methylations increase bacterial susceptibility to ribosome targeting antibiotics capreomycin and viomycin. The enzyme also function as a hemolysin, but increased bacterial hemolytic function is not likely a consequence of TlyA-mediated methylations of the ribosome |
-, 735991 |
| 2.1.1.227 | physiological function |
TlyA methylase modifies the rRNA position 1409, reducing the cost of the A1408G mutation while concomitantly also reducing the antibiotic resistance level, e.g. against capreomycin and viomycin. In response to capreomycin, cells downregulate TlyA-mediated methylation of 16S and 23S rRNA resulting in decreased drug susceptibility. Increased TlyA expression reduces resistance in the A1408G mutant and concomitantly increases fitness |
-, 758323 |
