title: Inhibition of aac(6')-Ib-mediated amikacin resistance by nuclease-resistant external guide sequences in bacteria.
abstract: Inhibition of bacterial gene expression by RNase P-directed cleavage is a promising strategy for the development of antibiotics and pharmacological agents that prevent expression of antibiotic resistance. The rise in multiresistant bacteria harboring AAC(6')-Ib has seriously limited the effectiveness of amikacin and other aminoglycosides. We have recently shown that recombinant plasmids coding for external guide sequences (EGS), short antisense oligoribonucleotides (ORN) that elicit RNase P-mediated cleavage of a target mRNA, induce inhibition of expression of aac(6')-Ib and concomitantly induce a significant decrease in the levels of resistance to amikacin. However, since ORN are rapidly degraded by nucleases, development of a viable RNase P-based antisense technology requires the design of nuclease-resistant RNA analog EGSs. We have assayed a variety of ORN analogs of which selected LNA/DNA co-oligomers elicited RNase P-mediated cleavage of mRNA in vitro. Although we found an ideal configuration of LNA/DNA residues, there seems not to be a correlation between number of LNA substitutions and level of activity. Exogenous administration of as low as 50 nM of an LNA/DNA co-oligomer to the hyperpermeable E. coli AS19 harboring the aac(6')-Ib inhibited growth in the presence of amikacin. Our experiments strongly suggest an RNase P-mediated mechanism in the observed antisense effect.
authors: Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas and Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina.
authors: Alfonso J C
authors: AJ
authors: Soler Bistué
authors: Fernando A
authors: FA
authors: Martín
authors: Nicolás
authors: N
authors: Vozza
authors: Hongphuc
authors: H
authors: Ha
authors: Jonathan C
authors: JC
authors: Joaquín
authors: Angeles
authors: A
authors: Zorreguieta
authors: Marcelo E
authors: ME
authors: Tolmasky
mesh_terms: D000123:Acetyltransferases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000583:Amikacin / Q000494:pharmacology*; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D004705:Endocytosis / Q000187:drug effects; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D009841:Oligonucleotides; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D043262:Ribonuclease P / Q000378:metabolism*
chemical_list: D009841:Oligonucleotides; D012333:RNA, Messenger; C477371:locked nucleic acid; D000583:Amikacin; D004247:DNA; D000123:Acetyltransferases; D043262:Ribonuclease P