Extended Data Fig. 9: The NAD⁺-binding site within SARM1^ARM.

a–c, Cryo-EM densities around the NAD⁺-binding site in three structures. NAD⁺ density is present in both the SARM1+NAD⁺ (b: blue mesh) and SARM1(E642A)+NAD⁺ (c: green mesh) structures but not the apo one (a). NAD⁺ is shown as magenta sticks. The density and atomic model of SARM1^ARM are shown as surface and ribbon, respectively. d,e, Cryo-EM densities for the residues of SARM1^ARM involved in the NAD⁺ binding. The densities of the SARM1+NAD⁺ structure are shown as orange mesh (d), and those of the SARM1(E642A)+NAD⁺ structure are shown as blue mesh (e). The residues are shown as sticks and coloured in green. The six residues interacting with NAD⁺ through their side chains are labelled. The contour levels of the maps in a–e are 6.0. f, g, The NAD⁺ affinity to SARM1(E642A) (f) and SARM1^ARM+TIR(WQH to A) (g). The experiments were biologically replicated twice and analysed (n = 2). The values of calculated K_d are presented as mean ± s.d. h, i, The HPLC analysis of the NADase kinetics of SARM1(RRK to A) (h) and SARM1^SAM+TIR (i). The background degradation of NAD⁺ was subtracted from each reaction. All the experiments were biologically replicated three times (n = 3). The kinetics of SARM1^SAM+TIR in i was fitted to the Michaelis–Menten equation. j, The NMN affinity to SARM1^ARM+SAM. The experiments were biologically replicated three times and analysed (n = 3). The value of calculated K_d is presented as mean ± s.d.

Source data