Molecular analysis of the Type 9 Secretion System

A newly discovered protein transport machine, the Type 9 Secretion System (T9SS), is the most complex export system known in bacteria, and researchers want to work out how it is built and how it operates. This matters because the bacteria that use T9SS—a group called Bacteroidota—are both essential for a healthy human gut and mouth, and responsible for serious anaerobic infections and severe dental disease. Despite their importance, scientists know surprisingly little about how these bacteria function at a molecular level. The T9SS is a key virulence factor, meaning it helps the harmful strains cause disease. If this research succeeds, it will provide the first detailed molecular blueprint of the T9SS: how its parts are organised, how energy is transferred from the inner to the outer bacterial membrane, and how the machine physically moves proteins across the cell envelope. This is fundamental science with no immediate practical application. However, understanding the T9SS could eventually open the door to designing new antibiotics that specifically disable this secretion system in pathogenic Bacteroidota, while leaving beneficial gut bacteria unharmed—a precision approach that current broad-spectrum antibiotics cannot offer.