Scientists have crystallised a protein that may help gut bacteria bind to the gastrointestinal tract. The breakthrough is potentially significant for the functional food sector because it is thought the protein could be used by manufacturers to develop more effective probiotic products.
The cells lining the gut are covered in a protective layer of mucus that is continuously renewed. As well as protecting the gut lining, this mucus provides an attachment site for beneficial bacteria that help maintain normal gut function.
Mucus adhesion has been studied for pathogenic bacteria, but precisely what enables friendly gut bacteria to stick is not known. However, in a paper published in the Journal of Biological Chemistry, scientists at the UK-based Institute of Food Research and University of East Anglia reveal they have identified and isolated 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. Mucus-binding proteins are more abundant in lactic acid bacteria than other types, and particularly in strains that inhabit the gut, and it is thought the presence of the proteins may contribute to the
"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," said Nathalie Juge from the Institute of Food Research. "The strain-specificity of these proteins demonstrates the need for the careful molecular design and selection of probiotics. This also opens new avenues of research to study the fundamental roles bacteria play in the gastrointestinal tract."
Crystal Structure of a Mucus-binding Protein Repeat Reveals an Unexpected Functional Immunoglobulin Binding Activity, The Journal of Biological Chemistry, 284, 32444-32453.