Substitutions of the Morgue Gly421 residue do not affect Morgue-induced lethality or cell death.

A. Schematic representation of Morgue point mutant proteins with Alanine, Cysteine, or Serine substitutions of the active site Glycine (residue 421). B. The progeny derived from P[da-Gal4], P[UAS-MorgueG421X]/TM3 parent flies were examined and the percentage of homozygotes/heterozygotes was determined. As for native Morgue, expression of each Morgue point mutant essentially resulted in completely lethality. Note that the expected percentage of homozygotes/heterozygotes is 50% if the homozygotes are fully viable. C. Enhancement of eye cell death in P[GMR-Gal4], P[UAS-R/Grim] flies by Morgue point mutants. Compared to GFP co-expression of native Morgue with R/Grim results in enhanced levels of eye cell death (evidenced by additional loss of pigment cells). Similar enhancement is observed for co-expression of the MorgueG421A, MorgueG421C, and MorgueG421S point mutants. D. Enhancement of Reaper-induced CNS midline cell death by Morgue Gly421 mutant proteins. The P[52a-Gal4] line was used to drive expression of P[UAS-LacZ] and P[UAS-Reaper] in embryonic CNS midline cells. Expression of Reaper alone does not induce significant amounts of cell death. Co-expression of native Morgue induces increased levels of CNS midline cell death. This enhanced death is somewhat enhanced by Morgue421A but is not significantly altered by either the MorgueG421C or MorgueG421S point mutant proteins. All views are sagittal with anterior to left. Stage 12 (P[UAS-Reaper] and PUAS-Morgue421A]), stage 16 (P[UAS-Morgue and P[UAS-MorgueG421C]), and stage15 (P[UAS-Reaper] and P[UAS-MorgueG421S]) embryos are shown.