In Caenorhabditis elegans the puromycin sensitive aminopeptidase PAM-1 has been shown to play a key role in embryonic meiotic exit and anterior-posterior (AP) axis determination. Mutations in
pam-1 lead to delays in meiotic exit and AP axis establishment. Despite the implication of PAM-1 in early embryonic axis specification, the mechanism by which it acts is currently unknown. We believe PAM-1 is involved in protein degradation and that a buildup of its target protein(s) contributes to the abnormal embryonic phenotypes. In an attempt to identify targets of PAM-1, we have taken a two-pronged approach. The first is to conduct a suppressor screen with temperature sensitive
pam-1 mutant strains. The rationale is that reduction of function mutations in PAM-1 target proteins, may partially rescue the lethality of the
pam-1 mutants. Additionally, we are taking a candidate gene approach. PTL-1 is a microtubule associated protein homologous to human Tau. Work in other systems suggests that Tau may be a target of puromycin sensitive aminopeptidases. Thus, we hypothesize that PTL-1 may be a PAM-1 target in C. elegans. We propose that the buildup of PTL-1 in C. elegans embryos leads to some of the abnormalities in
pam-1 mutants. To test this, we have created a
pam-1;
ptl-1 double mutant strain and will observe the phenotype. We expect a rescue of some of the
pam-1 phenotypes, namely those that depend on proper microtubule function. Identification of targets for PAM-1 will lead to a further understanding for the role of this aminopeptidases in controlling meiotic exit and axis formation in the early embryo.