Abstract:
Blood transfusion is an indispensable part of the health care system, saving many thousands of lives annually. Although significant improvements in the collection and use of blood have been made over the years, there are always shortages in the supply of blood. A solution to this problem could lie in the enzymatic conversion of A, B or AB blood groups into universal donor red blood cells, suitable for all blood types. However, no economically reasonable enzymes that catalyze this process are currently available. Access to efficient enzymes that can convert A- and B-type red blood cells to universal donor O-type is urgently needed.
The human gut mucus layer harbors mucins, glycoproteins presenting O-glycan structures like the A and B blood antigens, which are foraged by gut microorganisms, an ideal source of unexplored carbohydrate-active enzymes. A functional metagenomic screening of this environment identified a novel enzyme pair from the obligate anaerobe Flavonifractor plautii that work in concert to efficiently convert the A-antigen to the H-antigen of O-type blood, via a galactosamine intermediate. Their ability to completely convert A to O at very low enzyme concentrations in whole blood will simplify their incorporation into blood transfusion practice, broadening supply.