Dictyostelium puromycin-sensitive aminopeptidase A is a nucleoplasmic nucleomorphin-binding protein that relocates to the cytoplasm during mitosis.
Nucleomorphin (NumA1) is a nucleolar/nucleoplasmic protein linked to cell cycle in Dictyostelium. It interacts with puromycin-sensitive aminopeptidase A (PsaA) which in other organisms is a Zn(2+)-metallopeptidase thought to be involved in cell cycle progression and is involved in several human diseases. Here, we have shown that Dictyostelium PsaA contains domains characteristic of the M1 family of Zn(2+)-metallopeptidases: a GAMEN motif and a Zn(2+)-binding domain. PsaA colocalized with NumA1 in the nucleoplasm in vegetative cells and was also present to a lesser extent in the cytoplasm. The same localization pattern was observed in cells from slugs, however, in fruiting bodies PsaA was only detected in spore nuclei. During mitosis PsaA redistributed mainly throughout the cytoplasm. It possesses a functional nuclear localization signal ((680)RKRF(683)) necessary for nuclear entry. To our knowledge, this is the first nuclear localization signal identified in a Psa from any organism. Treatment with Ca(2+) chelators or calmodulin antagonists indicated that neither Ca(2+) nor calmodulin is involved in PsaA localization. These results are interpreted in terms of the inter-relationship between NumA1 and PsaA in cell function in Dictyostelium.
Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada. andrew.catalano@utoronto.ca
Andrew
A
Catalano
Yekaterina
Y
Poloz
Danton H
DH
O'Day
D000595:Amino Acid Sequence; D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000201:enzymology*; D004023:Dictyostelium / Q000201:enzymology*; D004330:Drosophila; D043384:Glutamyl Aminopeptidase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008938:Mitosis; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary / Q000235:genetics; D011691:Puromycin / Q000494:pharmacology; D015398:Signal Transduction; D014344:Trypanocidal Agents / Q000494:pharmacology
D002148:Calmodulin-Binding Proteins; D014344:Trypanocidal Agents; D011691:Puromycin; D043384:Glutamyl Aminopeptidase