1. J. H. Cate, K. Zhou, J. A. Doudna, Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520.
2. A. R. Gooding, E. Podell, B. L. Golden, A. A. Szewczak, T. R. Cech, Department of Chemistry and Biochemistry and Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309.
3. C. E. Kundrot, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309.