Most of the bacteria usually communicate our body’s inner mechanism by mouth and nose, which are regarded as the most common entry. Many people get diarrhoea when some of these bacteria which have entered become opportunistic. One of the most common is E. coli. These bacteria can able to attach themselves on the walls of the intestines and inject toxins which allow us to fall sick. But one thing which might be missing in between is that, these bacteria which follow their entry into digestive system should get killed by strong acid present in stomach, which we know as a strong barrier of infection.
A research group from “The Bacterial Cell Envelope” research centre at University of Tübingen with Tübingen University Hospitals, investigated the phenomenon how gut bacteria survives the strong acid of stomach to enter into intestines. The results were published in the journal Molecular Microbiology.
Commonly, E. coli and Yersinia are found in small intestines and absorb nutrients. A protein named as intimin (named after intimate adherence) which allows the bacterium to adhere to the intestinal walls. It also form tiny channels between the bacterial wall and the intestinal cells to allow the toxins (causing diarrhoea) to move into intestines.
Intimins are autotransporters and are important virulence factors of both E. coli and Yersinia spp. These proteins have lysin motif which allows the binding with the peptidoglycan. This binding is possible only in acidic conditions, which clearly displays the reason how these bacteria uses the stomach acid for getting resistance. The intimin gets inserted then into the bacterial envelope thus stabilizing the structure of peptidoglycan.
Scientists conclude that intimin supports infection process in intestine, using the stomach acid boosting the bacterial virulence.
Jack C. Leo, Philipp Oberhettinger, Manish Chaubey, Monika Schütz, Daniel Kühner, Ute Bertsche, Heinz Schwarz, Friedrich Götz, Ingo B. Autenrieth, Murray Coles, Dirk Linke: “The Intimin periplasmic domain mediates dimerisation and binding to peptidoglycan.” Molecular Microbiology, DOI:10.1111/mmi.12840