genetic reconstruction of protozoan rrna decoding sites provides a rationale for paromomycin activity against leishmania and trypanosoma原生动物的遗传重建rrna解码网站提供了一个理由巴龙霉素活动对利什曼虫和锥虫属.pdfVIP

Genetic Reconstruction of Protozoan rRNA Decoding Sites Provides a Rationale for Paromomycin Activity against Leishmania and Trypanosoma 1¤a 2,3 1¤b 1 1 Sven N. Hobbie , Marcel Kaiser , Sebastian Schmidt , Dmitri Shcherbakov , Tanja Janusic , Reto 2,3 ¨ 1 Brun , Erik C. Bottger * 1 Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland, 2 Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland, 3 University of Basel, Basel, Switzerland Abstract Aminoglycoside antibiotics target the ribosomal decoding A-site and are active against a broad spectrum of bacteria. These compounds bind to a highly conserved stem-loop-stem structure in helix 44 of bacterial 16S rRNA. One particular aminoglycoside, paromomycin, also shows potent antiprotozoal activity and is used for the treatment of parasitic infections, e.g. by Leishmania spp. The precise drug target is, however, unclear; in particular whether aminoglycoside antibiotics target the cytosolic and/or the mitochondrial protozoan ribosome. To establish an experimental model for the study of protozoan decoding-site function, we constructed bacterial chimeric ribosomes where the central part of bacterial 16S rRNA helix 44 has been replaced by the corresponding Leishmania and Trypanosoma rRNA sequences. Relating the results from in-vitro ribosomal assays to that of in-vivo aminoglycoside activity against Trypanosoma brucei, as assessed in cell cultures and in a mouse model of infection, we conclude that aminoglycosides affect cytosolic translation while the mitochondrial ribosome of trypanosomes is not a target for aminoglycoside antib