Naslov
Erm methylase inhibitor - a novel defense line to combat macrolide resistance

Autori
Maravić, Gordana ; Bujnicki, Janusz M. ; Feder, Marcin ; Pongor, Sandor ; Flögel, Mirna

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Third Croatian Congress on Pharmacy, Book of Abstracts / Zorc, Branka - Zagreb, 2006

Skup
Third Croatian Congress on Pharmacy

Mjesto i datum
Cavtat, Hrvatska, 27.04.2005. - 30.04.2005

Vrsta sudjelovanja
Poster

Vrsta recenzije
Domaća recenzija

Ključne riječi
macrolide antibiotics; resistance; Erm methylases; inhibitor

Sažetak
The most prevalent mechanism of the resistance to macrolide-lincosamide-straptogramin B (MLS) resistance is exhibited by the action of the enzymes from the erythromycin ribosome methylase (Erm) family. Erm enzymes methylate specific adenine residue within 23S rRNA, thus preventing antibiotic binding to the ribosome. To fight the MLS resistance based on ribosome methylation, a specific inhibitor of Erm MTases has to be found. With the aim to define the 23S rRNA binding site on Erm(C) we carried out the site-directed mutagenesis of conserved polar/charged residues and deletion analysis of the small domain. We tested the potential of 25 mutants to render bacteria resistant in the presence of erythromycin in vivo, while the changes in substrate binding and kinetic parameters were determined in vitro. The results of our studies show that RNA binds into concave positive charged crevice between the two domains of Erm(C), facing the catalytic domain. This contradicts previous predictions, which suggested that the small domain plays a role of an RNA binding module. Based on the experimental, we were able to build the model of Erm(C)-RNA interactions. The model clearly illustrates that the small domain is not involved directly in RNA binding. The deletion analysis, however, showed the indispensable character of the small domain, but with the function to stabilise the catalytic domain, rather than to directly bind the RNA. Additional sequence alignments and modelling of Erm(C) to the related enzyme from the Mycobacterium family that completely lacks the small domain reinforced the model of Erm-RNA interaction we suggested, which is fully in line with our experimental observations. Direct application of our results is in design of the specific inhibitor of Erm MTases. We offer a new approach, which would be based on blocking the enzyme-RNA interactions instead of inhibiting the catalytic reaction itself. This might be a new direction to restore the potency of MLS antibiotics and to overcome the threatening problem of bacterial resistance.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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