Leishmania cytosolic ribosome A-site

The Leishmania cytosolic ribosome A-site is a specialized region within the decoding center of the parasite's small (40S) ribosomal subunit. Its primary biological function is to facilitate the accurate selection and binding of aminoacyl-tRNA molecules during the elongation phase of protein translation (Shalev et al., 2015). In the context of disease, this site is the primary target for aminoglycoside antibiotics like paromomycin, which is used to treat various forms of leishmaniasis, including visceral and cutaneous types (Jhingran et al., 2009). When drugs bind to the A-site, they interfere with the fidelity of translation, causing the incorporation of incorrect amino acids or the complete arrest of protein synthesis, ultimately proving lethal to the parasite (Beckert et al., 2015). Although Leishmania is a eukaryote, its ribosomal A-site possesses unique structural features that distinguish it from the human cytosolic counterpart, providing a window for therapeutic intervention. However, the high conservation of ribosomal RNA across species means that drugs targeting this site must be carefully designed to avoid cross-reactivity with human mitochondrial ribosomes, which can lead to toxicities such as ototoxicity and nephrotoxicity. Research into the cryo-EM structure of the Leishmania ribosome has further elucidated how specific residues in the A-site contribute to drug sensitivity and resistance (Shalev et al., 2015).

Other names

Leishmania 40S ribosomal A-siteLeishmania decoding centerLeishmania ribosomal A-siteLeishmania ribosomal decoding site

The drug binds to the aminoacyl-tRNA binding site (A-site) of the 40S ribosomal subunit, inducing a conformational change that leads to the misreading of mRNA and the inhibition of the translocation step during protein synthesis (Shalev et al., 2015; Beckert et al., 2015).