Methionine Sustituted Polyamides are RNAse Mimics that Inhibit Translation

Aminoglycoside Conjugation for RNA Targeting: Antimicrobials and Beyond

Natural aminoglycosides are therapeutically useful antibiotics and very efficient RNA ligands. They are oligosaccharides that contain several ammonium groups able to interfere with the translation process in prokaryotes upon binding to bacterial ribosomal RNA (rRNA), and thus, impairing protein synthesis. Even if aminoglycosides are commonly used in therapy, these RNA binders lack selectivity and are able to bind to a wide number of RNA sequences/structures. This is one of the reasons for their toxicity and limited applications in therapy. At the same time, the ability of aminoglycosides to bind to various RNAs renders them a great source of inspiration for the synthesis of new binders with improved affinity and specificity toward several therapeutically relevant RNA targets. Thus, a number of studies have been performed on these complex and highly functionalized compounds, leading to the development of various synthetic methodologies toward the synthesis of conjugated aminoglycosides. The aim of this review is to highlight recent progress in the field of aminoglycoside conjugation, paying particular attention to modifications performed toward the improvement of affinity and especially to the selectivity of the resulting compounds. This will help readers to understand how to introduce a desired chemical modification for future developments of RNA ligands as antibiotics, antiviral, and anticancer compounds.

Use of Reticulocyte Lysates for Mechanistic Studies of Eukaryotic Translation Initiation

This chapter describes how commercially available, nuclease-treated rabbit reticulocyte lysates can be used to study different types of translation initiation (cap-dependent initiation, reinitiation, internal ribosome entry site-mediated initiation) and the influence of different initiation factors on these translation mechanisms. Additionally, with the use of sucrose gradients, it is possible to use nuclease-treated reticulocyte lysates to monitor the formation of ribosomal complexes for their content of mRNA, initiator met-tRNA(i), and initiation factors. The advantage of using nuclease-treated lysates rather than purified initiation factors is that reactions occur at or near the in vivo rate in contrast to rates observed in reactions with purified components, which are generally 10- to 1000-fold lower. The disadvantage is not being able to accurately control the amount of individual initiation factors, although the use of either factor additions or specific inhibitors can be helpful in assessing the role of specific individual initiation factors.