| Abstract: | Several genes related to the ubiquitin (Ub)-proteasome pathway, including thosecoding for proteasome subunits and conjugation enzymes, are differentially expressedduring the Schistosoma mansoni life cycle. Although deubiquitinatingenzymes have been reported to be negative regulators of protein ubiquitination andshown to play an important role in Ub-dependent processes, little is known abouttheir role in S. mansoni . In this study, we analysed the Ubcarboxyl-terminal hydrolase (UCHs) proteins found in the database of the parasite’sgenome. An in silico ana- lysis (GeneDB and MEROPS) identified threedifferent UCH family members in the genome, Sm UCH-L3,Sm UCH-L5 and Sm BAP-1 and a phylogeneticanalysis confirmed the evolutionary conservation of the proteins. We performedquantitative reverse transcription-polymerase chain reaction and observed adifferential expression profile for all of the investigated transcripts between thecercariae and adult worm stages. These results were corroborated by low rates ofZ-Arg-Leu-Arg-Gly-Gly-AMC hydrolysis in a crude extract obtained from cercariae inparallel with high Ub conjugate levels in the same extracts. We suggest that theaccumulation of ubiquitinated proteins in the cercaria and early schistosomulumstages is related to a decrease in 26S proteasome activity. Taken together, our datasuggest that UCH family members contribute to regulating the activity of theUb-proteasome system during the life cycle of this parasite. |
