Fig. 1. Structures of bGSDMs reveal homology with mammalian cell death effectors.

(A) Gasdermin phylogenetic tree. The sizes of the gasdermin NTDs and CTDs are depicted. Vertebrate gasdermins are labeled with single letters indicating human gasdermins GSDMA to GSDME (“A” to “E”), and “P” depicts pejvakin. The black teardrop indicates a conserved N-terminal cysteine(N-termin cys). A representative set of 20 fungal gasdermins are included in the tree. aa, amino acid. (B) Crystal structures of bGSDMs from species of the genera Bradyrhizobium and Vitiosangium. bGSDM structures reveal homology to the NTD of mammalian gasdermins in an inactive conformation including mouse GSDMA3 (Protein Data Bank ID 5B5R). (C) Gasdermin topology diagrams indicate a conserved central core of the bacterial and mammalian NTD. bGSDMs notably lack the CTD required for autoinhibition of mammalian gasdermins and instead encode a short C-terminal peptide. (D) Simulated annealing F_O−F_C omit map (contoured at 3.0 σ) from the Bradyrhizobium bGSDM fit with a palmitoyl modification at C3. Omit map is shown as green mesh and select residues forming a hydrophobic pocket around the palmitoyl group are indicated. (E) Melting temperatures (T_m) of bGSDMs with and without N-terminal cysteines, as determined with thermofluor assays. Data are the mean and standard deviation of three technical replicates and are representative of three independent experiments. WT, wild-type. Single-letter abbreviation for the amino acid residues are as follows: A, Ala; C, Cys; D, Asp; E, Glu; F, Phe; G, Gly; H, His; I, Ile; K, Lys; L, Leu; M, Met; N, Asn; P, Pro; Q, Gln; R, Arg; S, Ser; T, Thr; V, Val; W, Trp; and Y, Tyr.