Echinococcus granulosus: preparation of protein extracts from protoscolex nuclei for mobility-shift assays

Top Down Proteomics Reveals Mature Proteoforms Expressed in Subcellular Fractions of the Echinococcus granulosus Preadult Stage

Echinococcus granulosus is the causative agent of cystic hydatid disease, a neglected zoonosis responsible for high morbidity and mortality. Several molecular mechanisms underlying parasite biology remain poorly understood. Here, E. granulosus subcellular fractions were analyzed by top down and bottom up proteomics for protein identification and characterization of co-translational and post-translational modifications (CTMs and PTMs, respectively). Nuclear and cytosolic extracts of E. granulosus protoscoleces were fractionated by 10% GELFrEE and proteins under 30 kDa were analyzed by LC-MS/MS. By top down analysis, 186 proteins and 207 proteoforms were identified, of which 122 and 52 proteoforms were exclusively detected in nuclear and cytosolic fractions, respectively. CTMs were evident as 71% of the proteoforms had methionine excised and 47% were N-terminal acetylated. In addition, in silico internal acetylation prediction coupled with top down MS allowed the characterization of 9 proteins differentially acetylated, including histones. Bottom up analysis increased the overall number of identified proteins in nuclear and cytosolic fractions to 154 and 112, respectively. Overall, our results provided the first description of the low mass proteome of E. granulosus subcellular fractions and highlighted proteoforms with CTMs and PTMS whose characterization may lead to another level of understanding about molecular mechanisms controlling parasitic flatworm biology.

Characterisation of the proximal regulatory domain of the Echinococcus granulosus homeodomain-containing gene EgHbx1

In an attempt to understand the molecular basis of the development of Echinococcus granulosus, we have previously isolated several homeobox-containing genes (EgHbx1-5). Here we report the characterisation of the EgHbx1 proximal regulatory domain. EgHbx1 codes for an amino acid sequence presenting 90% identity at the homeodomain level with the Drosophila melanogaster NK1-S59 transcription factor. The proximal regulatory domain sequence and the transcription start site were determined. Electrophoretic mobility shift assays using nuclear extracts from protoscoleces revealed the presence of specific DNA-protein complexes. These results constitute a hint and provide new tools to decipher regulatory cascades during E. granulosus development.