Fig. 2: The molecular interface of the DSR2 tetramer.

a Ribbon diagram of the DSR2 tetramer. The four main interfaces for DSR2 oligomerization are boxed by black dash lines. b–d Close-up views of the DSR2 dimer interfaces 1 (b), 2 (c) and 3 (d), with interacting residues are highlighted as sticks. The hydrogen bonds are indicated by the black dash line. e Close-up view of the DSR2 tetramer interface 4 consisted of Sir2 domain, with the key residues for interaction shown as sticks. f NAD⁺ hydrolase activities of WT DSR2 or its mutants that disrupt the dimer or tetramer interfaces in the presence of TTP. In this assay, 1 μM of DSR2 WT or mutant proteins was preincubated with 8 μM TPP for 30 min. After the addition of 50 μM ε-NAD⁺, the reaction was conducted at 37 °C for 15 min. The fluorescence intensity was measured using the Bio Tek Synergy H1 Plate Reader. All assays were performed at least in triplicate (mean ± SD, n = 3 independent replicates), and the standard deviations were calculated using GraphPad Prism.