new biomarker: enzyme in the gut

Enzymes used by bacteria to break down mucus in the gut could provide a useful biomarker for intestinal diseases

Researchers at the University of Birmingham and Newcastle University have successfully identified and characterized one of the key enzymes involved in this process. They demonstrated how the enzyme enables bacteria to break down and feed off sugars in the layers of mucus lining the gut.

The molecules in mucus, called mucin, are constantly produced by the body to generate the layer of mucus in the gut that provides a barrier between the gut's complex populations of bacteria and the rest of the body. Mucin contain chains of sugar molecules called glycans, and these also provide an essential source of nutrients for bacteria.

The team investigated how this enzyme sits on the outside of the bacterial cell and clips away parts of the mucin molecule, taking them inside the bacterial cell to be consumed.

"Mucus is structured a bit like a tree, with lots of different branches and leaves. Lots of the enzymes discovered so far might clip away some of the leaves to eat, but the enzyme we studied will clip away a whole branch—that's quite a distinctive mechanism and it gives us a useful biomarker for studying disease."

 They found that by adding the enzyme to the samples and labelling the glycans with a fluorescent dye, they were able to get useful information about the glycan structure.

 

Mucus에서 Mucin이라는 분자가 나오는데, 이 분자는 gut bacteria를 보호하는 역할을 하는 동시에, 이 분자의 끝단에 달려있는 glycans를 통하여 bacteria에게 feeding한다고 한다. glycan 섭취를 위해서는 다른 부분을 잘라내야되는데, 그 역할을 하는 enzyme이 발견이 되었다.

특정 질병이 있는 경우 Mucin의 glycan 부분이 바뀌게 되는데, 환자의 mucin이 들어있는 sample에 enzyme을 넣어 떨어져 나간 glycan을 fluorescent dye를 통하여 염색한 뒤 확인해보았더니 질병이 있는 사람에게 변형이 된 것을 확인하였다.  

reference

Crouch et al (2020). 'Prominent members of the human gut microbiota express endo-acting O-1 glycanases to initiate mucin breakdown'. Nature Communications. DOI: 10.1038/s41467-020-17847-5