Schistosome egg production is dependent upon the activities of two developmentally regulated tyrosinases
Egg production is responsible for life cycle progression and host immunopathology during schistosomiasis, with the associated parasite molecules being investigated as potential novel chemotherapeutic targets. Here, we characterize two Schwtosoma mansoni products, tyrosinase 1 and tyrosinase 2 (SmTYRl SmTYR2) and show that their diphenol oxidase enzyme activities are critical for eggshell formation and produc tion. The genes encoding these bifunctional enzymes (monophenol and diphenol oxidases) result from a duplication event that likely occurred before speciation and exist in the parasite's genome as multiple copies, which are linked and localized to chromosomes 4 and W. SmTYRl/SmTYR2 transcription and diphenol oxidase action are developmentally regulated with most enzyme activity localized to the eggshell producing cells contained within the vitellaria of adult female worms. Importantly, kojic acid mediated inhibition (IC50=0.5mM) of SmTYRl/SmTYR2's diphenol oxidase activity during in vitro culture of sexually mature adult worms resulted in a significant decrease in the production of phenotypically normal eggs. Therefore our data suggest that SmTYRl /2 inhibition represents a novel and potentially effective strategy for combating schistosomiasis and furthermore, it may point to new methods for combinatorial control of immunopathology and egg transmission during platyhelminfh infection. Fitzpatrick J. M. Hirai Y. Hirai H. Hoffmann K. F. Schistosome egg production is dependent upon the activities of two developmentally regulated tyrosinases. FASEB J. 21, 823 835(2007)
FASEB journal official publication of the Federation of American Societies for Experimental Biology