Caging Bacteria

Normally, aprotein called septin is known for building scaffolding to provide structural support during cell division and to rope off other parts of the cell. However, a new study has shown that septin or GTP binding proteins may possibly build “cages” around invading bacteria. This action allows the bacteria to be stuck and thus prevents the bacteria from entering other healthy cells.

The way that septin’s method of trapping bacteria was discovered was through its interactions with Shigella. Shigella bacteria usually forces its way into neighboring host cells by using its actin-polymer tails. The immune system can combat this by producing a cell signaling protein called TNF-alpha. Due to the presence of TNA-alpha, septin filaments surround the bacteria and then prevents the Shigella Bacteria tail from moving. The bacteria is then broken down through autophagy which is a stage of the septin’s life cycle.  However, autophagy can only occur if the septin cage is present.

The role of septin is still mysterious in terms of humans. Some studies have shown that disruptions in septins and mutations in the gene that code for them could possibly be involved in diseases such as leukaemia, Parkinsons’ disease, etc.  Septin also holds great potential for therapies that could strengthen the immune system with drugs that imitate the behavior of TNA-alpha. This could allow for septin cages to be more prevalent and thus allow the immune system to fight an infection in a new way. Overall, the more research that is done on septin, the more possible it is to unlock the secrets in fighting infections and diseases.

http://www.nature.com/news/septin-proteins-take-bacterial-prisoners-1.9540