Fig. 5. The N-terminal helix is functionally important for RNA degradation.
a, CPMG relaxation dispersion profiles of Xrn2 ΔZnF N12CBTFA (gray) and Xrn2 ΔZnF A5F N12CBTFA (orange) at 11.7 T (500-MHz 1H frequency). Data points are shown as mean ± s.d., derived from three duplicate NMR measurements. b, Changes in the degradation rate of 5′-monophosphorylated AU10 and GC12 stem–loop RNAs by Xrn2, the Xrn2 A5F mutant, Xrn2 ΔZnF N12CBTFA and Xrn2 ΔZnF N12CBTFA A5F. The GC12 RNA is degraded approximately 20× slower than AU10, and the degradation rates are multiplied by 10 for clarity. Data points are shown as mean ± s.d., derived from two or four (Xrn2 ΔZnF N12C) independent experiments.