A sticky solution for identifying effective probiotics
24 November 2009
BBSRC-funded scientists at the Institute of Food Research (IFR) have crystallised a protein that may help gut bacteria bind to the gastrointestinal tract. The protein could be used by probiotic producers to identify strains that are likely to be of real benefit to people.
“Probiotics need to interact with cells lining the gut to have a beneficial effect, and if they attach to surfaces in the gut they are more likely to stick around long enough to exert their activity,” says Dr Nathalie Juge from IFR. IFR is an institute of BBSRC.
The gut is the largest immune system organ in the body. The cells lining the gut are covered in a protective layer of mucus that is continuously renewed by specialised cells. As well as protecting the gut lining, mucus provides an attachment site for beneficial bacteria that help maintain normal gut function.
Mucus adhesion has been well studied for pathogenic bacteria, but precisely what enables commensal (our gut bacteria) bacteria to stick is not known. In a paper published in The Journal of Biological Chemistry, IFR and UEA scientists have obtained the first crystal structure of a mucus-binding protein.
The protein was obtained from a strain of Lactobacillus reuteri, a lactic acid bacterium naturally found in the gastrointestinal tract. Lactic acid bacteria are the most common microorganisms used as probiotics.
These mucus-binding proteins are more abundant in lactic acid bacteria than other types and particularly in strains that inhabit the gut. The presence of the proteins may contribute to the ability of lactic acid bacteria to interact with the host.
The team of scientists found that these mucus-binding proteins also recognise human immunoglobulin proteins. These are an integral part of the immune system. Mucus-binding proteins may therefore also play a wider role in gut health as a site of attachment for bacteria.
“The strain-specificity of these proteins demonstrates the need for the careful molecular design and selection of probiotics,” says Dr Juge. “This also opens new avenues of research to study the fundamental roles bacteria play in the gastrointestinal tract.”
Notes to editors
Reference: Crystal structure of a mucus-binding protein repeat reveals an unexpected functional immunoglobulin binding activity, The Journal of Biological Chemistry, 284, 32444-32453.
The mission of the Institute of Food Research ( www.ifr.ac.uk) is to undertake international quality scientific research relevant to food and human health and to work in partnership with others to provide underpinning science for consumers, policy makers, the food industry and academia. It is a company limited by guarantee, with charitable status, grant aided by the Biotechnology and Biological Sciences Research Council ( www.bbsrc.ac.uk).
The Biotechnology and Biological Sciences Research Council (BBSRC) is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £450M in a wide range of research that makes a significant contribution to the quality of life for UK citizens and supports a number of important industrial stakeholders including the agriculture, food, chemical, healthcare and pharmaceutical sectors. BBSRC carries out its mission by funding internationally competitive research, providing training in the biosciences, fostering opportunities for knowledge transfer and innovation and promoting interaction with the public and other stakeholders on issues of scientific interest in universities, centres and institutes.
The Babraham Institute, Institute for Animal Health, Institute of Food Research, John Innes Centre and Rothamsted Research are Institutes of BBSRC. The Institutes conduct long-term, mission-oriented research using specialist facilities. They have strong interactions with industry, Government departments and other end-users of their research.
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