Figure 4.

Comparison of the Active Sites of RelE and RNase T1

(A) The active site of RNase T1 (orange cartoon) with critical amino acids shown as labeled sticks. The 3′-phosphate guanosine representing the 3′ end of the cleaved RNA and the guanosine representing the 5′ end are shown as purple sticks. Movements of protons during the reaction are shown with straight arrows (marked H⁺), and the nucleophilic attack of the 2′ oxyanion with a curved arrow.

(B) The corresponding region in RelE (blue cartoon) with residues implied in catalysis as blue sticks, and other nearby basic residues as yellow sticks. Residues critical for the activity of P. horikoshii RelE are marked with a ^∗ (Takagi et al., 2005). The nucleotides at positions 2 and 3 of the A site codon are shown as purple sticks and the scissile bond is marked with an arrow. The water molecule near the 2′-OH of position 2 (A20) is shown as a red sphere.

See also Figure S4.