Functions of the DNA damage response pathway target Ho endonuclease of yeast for degradation via the ubiquitin-26S proteasome system.
Ho endonuclease of Saccharomyces cerevisiae is a homing endonuclease that makes a site-specific double-strand break in the MAT gene in late G(1). Here we show that Ho is rapidly degraded via the ubiquitin-26S proteasome system through two ubiquitin-conjugating enzymes UBC2(Rad6) and UBC3(Cdc34). UBC2(Rad6) is complexed with the ring finger DNA-binding protein Rad18, and we find that Ho is stabilized in rad18 mutants. We show that the Ho degradation pathway involving UBC3(Cdc34) goes through the Skp1/Cdc53/F-box (SCF) ubiquitin ligase complex and identify a F-box protein, Yml088w, that is required for Ho degradation. Components of a defined pathway of the DNA damage response, MEC1, RAD9, and CHK1, are also necessary for Ho degradation, whereas functions of the RAD24 epistasis group and the downstream effector RAD53 have no role in degradation of Ho. Our results indicate a link between the endonuclease function of Ho and its destruction.
Kaplun
L
L
Life Sciences Department, Ben Gurion University of the Negev, Box 653, Beersheba 84105, Israel.
Ivantsiv
Y
Y
Kornitzer
D
D
Raveh
D
D
D064173:Anaphase-Promoting Complex-Cyclosome; D002453:Cell Cycle; D004249:DNA Damage; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism*; D006207:Half-Life; D007700:Kinetics; D008025:Ligases / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D044763:Ubiquitin-Conjugating Enzymes; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*
D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins; C577449:CDC34 protein, S cerevisiae; C471606:RAD6 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases; C530845:HO protein, S cerevisiae; C037725:SCEI protein, S cerevisiae; D015252:Deoxyribonucleases, Type II Site-Specific; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D008025:Ligases