Type VII secretion--mycobacteria show the way

Area of Science:

• Microbiology
• Cell Biology
• Bacterial Pathogenesis

Background:

• Mycobacteria possess unique, highly impermeable cell walls.
• Several novel protein secretion systems have been identified in mycobacteria.
• Two systems, ESX-1 and ESX-5, are implicated in the virulence of pathogenic mycobacteria.

Purpose of the Study:

• To discuss the novel secretion pathway in mycobacteria.
• To examine variants of this pathway in Gram-positive bacteria.
• To propose a standardized nomenclature for this secretion system.

Main Methods:

• Bioinformatic analysis of mycobacterial genomes.
• Comparative genomics of Gram-positive bacteria.
• Literature review of protein secretion systems.

Main Results:

• Mycobacterial genomes encode up to five distinct protein transport systems.
• ESX-1 and ESX-5 secretion systems are crucial for mycobacterial virulence and cell migration.
• The pathway shows variations across different Gram-positive bacterial species.

Conclusions:

• The novel secretion pathway is essential for mycobacteria.
• This system plays a significant role in bacterial pathogenesis.
• The proposed name 'type VII secretion' is recommended for this system.