Secondary structure of aac(6')-Ib mRNA. The image was generated with the mfold software (Zuker, M., D. H. Mathews, and D. H. Turner. 1999. Algorithms and thermodynamics for RNA secondary structure prediction: a practical guide, p. 11-43. In J. Barciszewski and B. Clark (ed.), RNA biochemistry and biotechnology. Kluwer Academic Publishers, Dordrecht, The Netherlands). The nucleotides over a black background indicate the regions identified by RNase H mapping. Figure taken from Sarno et al. Antimicrob. Agents Chemother. 2003 47:3296-3304.