Pore‐forming Toxins

Abstract

AbstractPore‐forming toxins (PFT) are proteins able to produce well‐structured holes in target cell membrane. They have a very broad taxonomic distribution being produced from bacteria to mammals. Depending on the secondary structure of the membrane‐spanning region, these proteins are categorised into two classes: α‐PFT and β‐PFT. The pore structure of representative members of each class will be described. These proteins can be also classified according to their pore structure:barrel‐staveandtoroidalprotein–lipid pore. In thebarrel‐stavepore the protein molecules provide a continuous interface between the core of the bilayer and the channel lumen, whereas in thetoroidalprotein–lipid pore both polypeptide chains and polar phospholipid headgroups are involved in the building of pore walls. The stoichiometry and the pore diameter depend on the protein, thus the channels can allow leakage of ions, adenosine triphosphate (ATP), proteins and even bacteria. Attacked cells trigger different responses, some promoting recovery of membrane integrity, others transition to a low‐energy‐consumption state, in addition to inflammatory responses and changes in gene transcription.Key Concepts:Pore‐forming toxins are proteins produced from bacteria to mammals.Pore‐forming toxins are classified as α‐PFT and β‐PFT, according to the structure adopted by the transmembrane region.Pores are nanometre funnel‐like holes that permit the passage of water, ions and small molecules through cell membranes.PFT form two types of pores, the barrel‐stave and the toroidal protein–lipid pore.Cells react to pore formation, repair the damage and survive.