Xkid is degraded in a D-box, KEN-box, and A-box-independent pathway.
During mitosis, the Xenopus chromokinesin Kid (Xkid) provides the polar ejection forces needed at metaphase for chromosome congression, and its degradation is required at anaphase to induce chromosome segregation. Despite the fact that the degradation of Xkid at anaphase seems to be a key regulatory factor to induce chromosome movement to the poles, little is known about the mechanisms controlling this proteolysis. We investigated here the degradation pathway of Xkid. We demonstrate that Xkid is degraded both in vitro and in vivo by APC/Cdc20 and APC/Cdh1. We show that, despite the presence of five putative D-box motifs in its sequence, Xkid is proteolyzed in a D-box-independent manner. We identify a domain within the C terminus of this chromokinesin, with sequence GxEN, whose mutation completely stabilizes this protein by both APC/Cdc20 and APC/Cdh1. Moreover, we show that this degradation sequence acts as a transposable motif and induces the proteolysis of a GST-GXEN fusion protein. Finally, we demonstrate that both a D-box and a GXEN-containing peptides completely block APC-dependent degradation of cyclin B and Xkid, indicating that the GXEN domain might mediate the recognition and association of Xkid with the APC.
Castro
Anna
A
Centre de Recherche de Biochimie Macromoléculaire, CNRS UPR 1086, 34293 Montpellier Cedex 5, France.
Vigneron
Suzanne
S
Bernis
Cyril
C
Labbé
Jean-Claude
JC
Lorca
Thierry
T
D020816:Amino Acid Motifs; D000705:Anaphase; D000818:Animals; D015153:Blotting, Western; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism*; D008677:Metaphase; D008938:Mitosis; D008957:Models, Genetic; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D014981:Xenopus; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C490913:KIFF22 protein, Xenopus; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D029867:Xenopus Proteins; D005982:Glutathione Transferase; D016547:Kinesins