engleski

Identification of essential residues in ErmC' rRNA methyltransferase

Bacterial resistance to macrolide-lincosamide-streptogramin B antibiotics is mediated most commonly by the action of Erm family of rRNA methyltransferases, that mono- and dimethylate specific adenine residue within 23 S rRNA, thus preventing antibiotic binding to ribosome. We have undertaken a mutational analysis of ErmC' methyltransferase from Bacillus subtilis with the objective of developing a greater understanding of the mechanism of action of this protein. Amino acids predicted to be important for ErmC' function were changed to alanines by site-directed mutagenesis. Mutant genes were checked in the in vivo tests for the ability to mediate the erythromycine resistance in naturally sensitive E. coli. Several mutants were found to be defective in rescuing the bacterial growth, which was also confirmed by preliminary in vitro tests with purified mutant proteins. These amino acids therefore represent important factors for the ErmC&#8217 ; function and can be considered as potential targets for the rational development of methyltransferase inhibitors.

ErmC'; antibiotic resistance; site-directed mutagenesis; RNA binding; catalysis

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