Bacterial Type II Secretion System and Its Mitochondrial Counterpart

Over the billions of years that bacteria have been around, they have evolved several sophisticated protein secretion nanomachines to deliver toxins, hydrolytic enzymes, and effector proteins into their environments. Of these, the type II secretion system (T2SS) is used by Gram-negative bacteria to export a wide range of folded proteins from the periplasm across the outer membrane. Recent findings have demonstrated that components of the T2SS are localized in mitochondria of some eukaryotic lineages, and their behavior is consistent with the presence of a mitochondrial T2SS-derived system (miT2SS). This review focuses on recent advances in the field and discusses open questions concerning the function and evolution of miT2SSs. Over the billions of years that bacteria have been around, they have evolved several sophisticated protein secretion nanomachines to deliver toxins, hydrolytic enzymes, and effector proteins into their environments. Of these, the type II secretion system (T2SS) is used by Gram-negative bacteria to export a wide range of folded proteins from the periplasm across the outer membrane.

Automated summary

Bacteria have evolved sophisticated protein secretion nanomachines over billions of years to deliver toxins, enzymes, and proteins. The type II secretion system (T2SS) is used by Gram-negative bacteria to export folded proteins across the outer membrane. Recent findings have shown that components of the T2SS can be found in the mitochondria of certain eukaryotic lineages, suggesting the presence of a mitochondrial T2SS-derived system (miT2SS). This review discusses recent advances in the field and raises questions about the function and evolution of miT2SSs.