Combatting gum disease

17th January 2019

News

A structure which promotes severe dental disease has been revealed by Wadham-led scientists.

  • Images showing the newly discovered structure

New research from groups led by Wadham Fellows Ben Berks (Biochemistry) and Susan Lea (Pathology) reveals how proteins are transported across the outer membrane of the bacteria responsible for severe dental disease (peridontitis).

This work, published in Nature, has uncovered an enormous transmembrane beta barrel structure through which the proteins move.

Disease causing pathogenic bacteria must be able to secrete proteins in order to manipulate their host organisms. Major oral pathogens such as Porphyromonas gingivalis export these proteins across two cell membranes. Protein transport across the outer membrane in these bacteria utilises the recently discovered Type IX Secretion System (T9SS).

All protein transport systems have to provide a pathway across the cell membrane in which they are located. However, for the T9SS it was unknown which proteins build this protein conducting pathway, or translocon. A joint effort by Drs. Frédéric Lauber and Justin Deme working in the Berks and Lea groups has now identified the translocon and determined its structure in two mechanistically relevant states.

“Before making this discovery we did not know how the proteins were getting through the membrane and which components were involved – it was very exciting to identify this new structure,” said Professor Ben Berks, Wadham’s Tutor in Biochemistry.

“Recent advances in electron microscopy, recognised by the award of the 2017 Nobel Prize in Chemistry, have revolutionised structural biology,” he added.

Wadham Fellow, Professor Susan Lea commented: “Since taking delivery of a new electron microscope back in summer 2017 many projects have accelerated, of which this is one exciting example.”

This discovery opens a number of exciting possibilities adds Ben. “In principle, an understanding of this structure provides a potential drug target with the possibility of preventing the causes of severe gum disease. It could also have an impact on fish farming as the T9SS is involved in the major diseases of cold water fish.”