SOLUTION STRUCTURE OF THE TOBRAMYCIN-RNA APTAMER COMPLEX

We have solved the solution structure of the aminoglycoside antibiotic tobramycin complexed with a stem-loop RNA aptamer. The 14 base loop o f the RNA aptamer 'zippers up' alongside the attached stem through ali gnment of four mismatches and one Watson-Crick pair on complex formati on. The tobramycin inserts into the deep groove centered about the mis match pairs and is partially encapsulated between its floor and a loop ed out guanine base that naps over the bound antibiotic. Several poten tial intermolecular hydrogen bonds between the charged NH, groups of t obramycin and acceptor atoms on base pair edges and backbone phosphate s anchor the aminoglycoside antibiotic within its sequence/structure s pecific RNA binding pocket.