Investigating Type VII substrates within Mycobacterium species
Non--tuberculous mycobacteria, including Mycobacterium abscessus, are an emerging group of opportunistic pathogens capable of causing chronic infections in immunocompromised groups. The prevalence of M. abscessus has increased over the past decade within the UK cystic fibrosis population, making it a pathogen of notable concern. Like Bacillota, mycobacteria encode type VII protein secretion systems (T7SS), termed ESX systems, which are multi-protein complexes embedded in the cytoplasmic membrane. M. abscessus encode two ESX systems – ESX-3 and ESX-4. The function of ESX-3 is implicated with iron scavenging both from the environment and from macrophages during infection; whereas the biological role of ESX-4 and its substrates remains elusive.