Fig. 3: Gp54Bas11 and MCPSECΦ27 bind overlapping but distinct regions of CapRelSJ46.
From: A bacterial immunity protein directly senses two disparate phage proteins
a, Serial dilutions of cells producing the indicated variant of CapRelSJ46 from its native promoter and wild-type Gp54Bas11 from an arabinose-inducible promoter on medium containing glucose or arabinose. b, Left, cartoon representation of the crystal structure of Gp54Bas11. Right, topological representation of Gp54Bas11 in an unbound, β-barrel state. c, Left, crystal structure of the complex of Gp54Bas11 (purple) bound to CapRelSJ46 (coloured by domains). Right, predicted structural model of the complex of CapRelSJ46 and MCPSECΦ27 (pink) by AlphaFold. ATP-coordination residues of the CapRelSJ46 toxin domain are highlighted in red. d, Details of the interface formed by the antitoxin domain of CapRelSJ46 and Gp54Bas11 (purple), with the residues substituted coloured in blue. e, Topological representation of Gp54Bas11 (purple) in a CapRelSJ46-bound state involving interaction with the pseudo-ZFD of CapRelSJ46 (orange). f, Differential HDX (ΔHDX) between CapRelSJ46 and CapRelSJ46–Gp54Bas11 shown as a differential heat map. Change in relative fractional units (ΔRFU) is colour coded, with red indicating increased deuteration of CapRelSJ46 in the presence of Gp54Bas11 and blue indicating lower deuteration. Grey bars indicate peptides identified in mass spectrometry analysis. Regions corresponding to the toxSYNTH active site highlighted by dashed-line boxes. g, As in f but comparing Gp54Bas11 and CapRelSJ46–Gp54Bas11. h, As in a but with the wild-type MCP from SECΦ27. i, CapRelSJ46–Flag or the indicated variant was immunoprecipitated from cells producing CapRelSJ46–Flag and Gp54Bas11–HA or MCPSECΦ27–HA, and probed for the presence of Gp54Bas11 or MCPSECΦ27 using the HA tag. Image shown is representative of two biological replicates.
