RESUMO
The effect of several peptidyltransferase inhibitors on ribonuclease P activity from Dictyostelium discoideum was investigated. Among the inhibitors tested puromycin, amicetin and blasticidin S revealed a dose-dependent inhibition of tRNA maturation. Blasticidin S and amicetin do not compete with puromycin for the same site on the enzyme, suggesting the existence of distinct antibiotic binding sites on D. discoideum RNase P. Inhibition experiments further indicate that binding sites for blasticidin S and amicetin overlap.
Assuntos
Dictyostelium/enzimologia , Endorribonucleases/metabolismo , Inibidores Enzimáticos/farmacologia , Peptidil Transferases/antagonistas & inibidores , RNA Catalítico/metabolismo , Animais , Antibacterianos/farmacologia , Sistema Livre de Células , Endorribonucleases/antagonistas & inibidores , Concentração Inibidora 50 , Nucleosídeos/farmacologia , Puromicina/farmacologia , Nucleosídeos de Pirimidina/farmacologia , RNA Catalítico/antagonistas & inibidores , Ribonuclease PRESUMO
The effect of several aminoglycoside antibiotics on ribonuclease P (RNase P) was investigated using an in vitro experimental system from Dictyostelium discoideum. Detailed kinetic analysis showed that all aminoglycosides tested (tobramycin, gentamicin, kanamycin, paromomycin, neomycin) behave as classical non-competitive inhibitors, with neomycin being the strongest inhibitor. The inhibition effect is attributed to the electrostatic competition of the cationic aminoglycosides with magnesium ions required for catalysis. Increasing Mg(2+) ion concentrations reduced the effect of aminoglycosides on RNase P activity. Detailed kinetic analysis showed that aminoglycosides compete with Mg(2+) for common binding sites on RNase P holoenzyme.
