SmSak, the Second Polo-Like Kinase of the Helminth Parasite Schistosoma mansoni: Conserved and Unexpected Roles in Meiosis
Figure 6
Studies of the importance of SmPlk1 and SmSak domains for oocyte maturation by using SmPlk1/SmSak hybrid constructs.
A. Schematic representation of Kin1-PBD4 and Kin4-PBD1 hybrids formed by the fusion of the N-terminal part of SmPlk1 (AA 1–342) with the C-terminal SmSak (AA 323–618) and that of N-terminal SmSak (AA 1–322) with C-terminal SmPlk1 (AA 343–903), respectively (refer to Figure 1). B. Different sets of Plx1-depleted oocytes were microinjected with cRNA encoding SmPlk1, SmSak, Kin1-PBD4 or Kin4-PBD1, or their unphosphorylable variants, and stimulated by the addition of PG. GVBD monitored 18 h after microinjection of cRNA, only occurred in oocytes expressing SmPlk1 and Kin4-PBD1 that contain phosphorylable T182 and T175, respectively. Western blot analysis of oocyte extracts with anti-V5 antibodies confirmed the expression of proteins in oocytes. Gel shift of Cdc25 was detected only in matured oocytes.