Fig. 1

a Schematic representation of the alignment of capC3 and capD2 genes which are representative of the larger capC and capD families. The C-terminal β-barrel domain (red) between capC and capD genes is strongly conserved yet the N-terminal passenger domain sequence (grey) is highly divergent. The homopolymeric tract (denoted by yellow arrow heads) associated with capC autotransporters is upstream of the start codon, in the putative promoter region. The homopolymeric tract associated with capD autotransporters is located within the coding sequence. b Alignment trees generated using MEGA7 based on full length protein sequences (left) and the conserved C-terminal sequence (right) displaying the relatedness of CapC and CapD autotransporters identified in this study. Clustering of each of these two, distinct families is clear. Highlighted in yellow are autotransporter genes that lack a homopolymeric tract. c Alignment trees generated using MEGA7 based on full length protein sequences (left) and the conserved C-terminal sequence (right) displaying the relatedness of autotransporters belonging to the CapC and CapD families identified in a range of Campylobacter species. Highlighted in yellow are autotransporter genes that lack a homopolymeric tract