In a major scientific breakthrough, researchers identified the enzyme that causes urine to appear yellow, revealing the critical role of the gut microbiome in human health and disease management. Researchers at the University of Maryland and the National Institutes of Health have discovered microbial enzymes that make urine appear yellow, according to a new study published Jan. 3, 2024 in the journal Nature Microbiology.
The discovery of this enzyme, known as bilirubin reductase, paved the way for further research into the role of the gut microbiome in diseases such as jaundice and inflammatory bowel disease.
Brantley Hall, lead author of the study and assistant professor in the Department of Cell Biology and Molecular Genetics at the University of Maryland, said:"The discovery of this enzyme has finally unraveled the mystery behind the yellow color of urine. Our team is happy to be able to explain this phenomenon. "
Heme degradation pathway**. Key human enzymes are highlighted in gray text. Hall et al., Nature Microbiology
When red blood cells degrade after six months of life, a bright orange pigment called bilirubin is produced as a byproduct. Bilirubin is normally secreted into the intestine and then excreted from the body, but it can also be partially reabsorbed. Excessive reabsorption can cause bilirubin to build up in the bloodstream and cause jaundice – a condition that causes ** and yellowing of the eyes. Once in the gut, the resident flora is able to convert bilirubin into other molecules.
Hall explained"Gut microbes encode bilirubin reductase, an enzyme that converts bilirubin into a colorless byproduct called uropirin. Urochrome then spontaneously degrades into a molecule called uroflavin, which is why the yellow color we are familiar with appears. "
Ulavinin has long been associated with the yellow hue of urine, but the enzyme discovered by the team answers questions that have puzzled scientists for more than a century.
Impact on health and disease
In addition to solving scientific mysteries, these discoveries could also have important health implications. The team found that bilirubin reductase is present in almost all healthy adults, but it is often lacking in newborns and people with inflammatory bowel disease. They hypothesized that the absence of bilirubin reductase may contribute to the formation of infantile jaundice and pigmented gallstones.
Xiaofang Jiang, a co-author of the study and a researcher at the National Institutes of Health, said"Now that we've identified this enzyme, we can begin to look at how bacteria in the gut affect circulating bilirubin levels and related health conditions such as jaundice. This discovery lays the foundation for understanding the gut-liver axis. "
The role of the gut microbiome in human health
In addition to jaundice and inflammatory bowel disease, the gut microbiome has been linked to a variety of diseases and conditions, from allergies and arthritis to psoriasis. This latest finding brings researchers closer to a comprehensive understanding of the gut microbiome's role in human health.
Hall said"Thanks to the collaboration between our labs, we are able to implement a multidisciplinary approach that is key to solving the physiological dilemma of yellow urine. This is the culmination of years of work by our team and is another reason why the gut microbiome is vital to human health. "
Compilation**: scitechdaily