Fig. 1: The methyltransferase reaction and the overall structure of the MTR1 ribozyme.
From: Structure and mechanism of a methyltransferase ribozyme
a, The chemical reaction in which the methyl group of exogenous O6-methylguanine becomes transferred to N1 of a specific adenine in the RNA. b, The sequence of the MTR1 ribozyme as crystallized in this work. The same color scheme is used throughout the paper. The RNA is a three-way junction composed of the three arms P1, P2 and P3. For the crystallographic study, a GNRA tetraloop has been added to the end of the P3 helix so that the entire ribozyme comprises a single RNA strand. Subsections of the strands are named J12 (colored green), J23 (colored blue) and J31 (colored red). c, Parallel-eye stereoscopic image of the complete MTR1 ribozyme structure. The bound guanine (guan) is colored cyan, and the methylation target A63 is colored magenta. Note that as the methyl transfer reaction is complete in the crystal, the exogenous base is guanine, and N1-methyladenine is present at position 63. d, Schematic of the structure of the junction with the bound guanine. The inset (top right) is a schematic showing the path of the strands at the junction observed from the minor groove side of the junction.
