Source-SciTechDaily
Researchers have made a significant scientific advancement by identifying the enzyme that gives urine its yellow hue, highlighting the critical role the gut microbiota plays in maintaining human health and treating disease.
A recent study that was published in the journal Nature Microbiology on January 3, 2024, revealed the microbial enzyme that gives urine its yellow colour. The researchers were affiliated with the University of Maryland and the National Institutes of Health.
The identification of microbial enzyme, known as bilirubin reductase, opens the door to additional investigation into the function of the gut microbiota in conditions such as inflammatory bowel disease and jaundice.
Enzyme: Dissecting Biological Enigmas
According to Brantley Hall, the study’s primary author and an assistant professor in the Department of Cell Biology and Molecular Genetics at the University of Maryland, “microbial enzyme discovery finally unravels the mystery behind urine’s yellow colour.” “Our team is thrilled to be able to explain an everyday biological phenomenon that went unexplained for such a long time.”
After red blood cells have lived for six months, they break down, producing bilirubin, a vivid orange pigment, as a byproduct. Normally produced into the stomach, bilirubin is excreted there, though it may also be partly reabsorbed. A buildup of bilirubin in the bloodstream caused by excessive reabsorption can result in jaundice, a disorder that causes the skin and eyes to turn yellow. After bilirubin enters the stomach, it can be changed into different molecules by the local flora.
“The bilirubin reductase enzyme, which is encoded by gut microbes, transforms bilirubin into urobilinogen, a colourless byproduct,” said Hall, who holds a joint post at the University of Maryland Institute for Advanced Computer Studies.
“After then, urobilinogen spontaneously breaks down into urobilin, the molecule that gives our familiar yellow colour.”
While urine’s yellow colour has long been associated with uribinin, the study team’s identification of the corresponding enzyme provides a solution to a conundrum that has baffled scientists for more than a century.
What Makes Urine Yellow? Maryland Scientists Discover the Enzyme Responsible
Consequences for Disease and Health
These results not only resolve a scientific enigma but may also have significant health ramifications. The study team discovered that whereas bilirubin reductase is typically absent in infants and those with inflammatory bowel disease, it is present in nearly all healthy adults. They speculate that neonatal jaundice and the development of pigmented gallstones may be caused by the lack of bilirubin reductase.
Xiaofang Jiang, an NIH Investigator and study co-author, said, “Now that we’ve identified microbial enzyme, we can start investigating how the bacteria in our gut impact circulating bilirubin levels and related health conditions like jaundice.” “This finding establishes the framework for comprehending the stomach-liver axis.”
The Function of Gut Microbiota in Human Health
Apart from inflammatory bowel disease and jaundice, the gut microbiota has been connected to a number of illnesses and ailments, such as psoriasis, allergies, and arthritis. With this most recent finding, scientists are getting closer to developing a comprehensive knowledge of the function of the gut microbiome in human health.
“The physiological mystery of why our urine appears yellow was solved thanks to the multidisciplinary approach we were able to implement—thanks to the collaboration between our labs,” Hall stated. It’s the result of years of research by our group and provides more evidence for the critical role that the gut microbiota plays in maintaining human health.
Reference: “BilR is a gut microbial enzyme that reduces bilirubin to urobilinogen” by Brantley Hall, Sophia Levy, Keith Dufault-Thompson, Gabriela Arp, Aoshu Zhong, Glory Minabou Ndjite, Ashley Weiss, Domenick Braccia, Conor Jenkins, Maggie R. Grant, Stephenie Abeysinghe, Yiyan Yang, Madison D. Jermain, Chih Hao Wu, Bing Ma and Xiaofang Jiang, 3 January 2024, Nature Microbiology.
In addition to Hall, UMD-affiliated co-authors included Stephenie Abeysinghe (B.S. ’23, public health science); Domenick Braccia (Ph.D. ’22, biological sciences); biological sciences major Maggie Grant; biochemistry Ph.D. student Conor Jenkins; biological sciences Ph.D. students Gabriela Arp (B.S. ’19, public health science; B.A. ’19, Spanish language), Madison Jermain, Sophia Levy (B.S. ’19, chemical engineering; B.S. ’19, biological sciences) and Chih Hao Wu (B.S. ’21, biological sciences); Glory Minabou Ndjite (B.S. ’22, public health science); and Ashley Weiss (B.S. ’22, biological sciences).
This research was supported by the NIH’s Intramural Research Program, the National Library of Medicine and startup funding from UMD. This article does not necessarily reflect the views of these organizations.
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