Bacterial type VII secretion: An important player in host?microbe and microbe?microbe interactions

Type VII secretion systems (T7SSs) are poorly understood protein export apparatuses found in mycobacteria and many species of Gram-positive bacteria. To date, this pathway has predominantly been studied Mycobacterium tuberculosis, where it shown to play an essential role virulence; however, much less is evolutionarily divergent subfamily T7SSs referred as the T7SSb. The T7SSb major phylum Firmicutes was recently target both eukaryotic prokaryotic cells, suggesting a dual for host-microbe microbe-microbe interactions. In review, we compare current understanding molecular architectures substrate repertoires well-studied mycobacterial T7SSa that characterized pathways highlight how these differences may explain observed biological functions understudied machine.