Nature Structural & Molecular Biology 12, 1072–1077 (2005); published online 20 November 2005; corrected after print 14 April 2006

In the supplementary information initially published online to accompany this article, the legend of Supplementary Figure 1 describes a 500-nt Mini-T RNA secondary structure model, but the model for the 436-nt Mini-T is shown. The secondary structure model for the 500-nt Mini-T has now been supplied by the authors. The error has been corrected online.