Extended Data Fig. 4: Structural homology search reveals an ADP-ribosyltransferase (ART) domain-like fold in OspC3-N domain.

a, Dali search results of OspC3-N domain structure (from the MBP-OspC3–CaM complex). b, Cartoon schemes of ART prototypes, including OspC3 (this study) and the ART domains of diphtheria toxin (PDB code: 1TOX) and cholera toxin (PDB code: 2A5F). The conserved central β-sheets are colored in orange and the catalytic triads are shown in sticks. c, Sequence alignment of the N-terminal domains from different OspC3 homologues. The catalytic triad residues are highlighted by magenta arrowheads on top of the sequence. Residues involved in binding to CaM are boxed in green. Identical residues are in red background and conserved residues are in red. Numbers of the starting residues are indicated on the left. Accession number of OspC3 homologues are the same as previously reported¹⁹.