Figure 2.

Model of ESX-5-dependent secretion mechanism. The hypothetical model depicts the parent ESX-5 Esx protein pair (EsxM/N) and cognate duplicate paralogs from ESX-5a (EsxI/J), ESX-5b (EsxK/L), and ESX-5c (EsxV/W) regions as having a role in substrate selection via the core ESX-5 secretion machinery and that these secreted effectors in turn manipulate various host defense processes. The EsxM protein is shown in dotted outline to indicate that it is a pseudogene. The experimental findings supporting a role of ESX-5a were extrapolated for ESX-5b and ESX-5c, which is indicated by the question marks. The circles represent putative secretion substrates associated with each of these systems. Some of these substrates may be shared between the different paralogs.