Fig. 4: Recognition of the cofactor substrate.

a Detailed interactions between SAM and MTase domain of TthMTA1. Residues involved in SAM binding are shown as violet sticks. SAM is shown as green sticks. Water is shown as red spheres. Hydrogen bonds are shown as black dashed lines. b Detailed interactions between SAH and MTase domain of TthMTA1. Residues involved in SAH binding are shown as violet sticks. SAH is shown as yellow sticks. Water is shown as red spheres. Hydrogen bonds are shown as black dashed lines. c Antibody-based methyltransferase activity of the TthMTA1c complexes with indicated MTA1 point mutations. Each mutation does not affect MTA1-MTA9-p1-p2 complex formation. Each MTA1-MTA9-p1-p2 mutant complex used for enzymatic assay was expressed and purified as MTA1-MTA9-p1-p2 WT complex. A 954-bp dsDNA PCR product was sued as the substrate. Data are shown as mean ± SD from n = 3 independent experiments; open circles indicate values for individual repeat measurements. d ITC assay of the TthMTA1c complexes with indicated MTA1 point mutations. Each MTA1-MTA9-p1-p2 mutant complex used for ITC assay was purified as MTA1-MTA9-p1-p2 WT complex. Source data for (c) are provided in a Source Data file.