Timing of APC/C substrate degradation is determined by fzy/fzr specificity of destruction boxes.
The anaphase promoting complex/cyclosome (APC/C), activated by fzy and fzr, degrades cell cycle proteins that carry RXXL or KEN destruction boxes (d-boxes). APC/C substrates regulate sequential events and must be degraded in the correct order during mitosis and G(1). We studied how d-boxes determine APC/C(fzy)/APC/C(fzr) specificity and degradation timing. Cyclin B1 has an RXXL box and is degraded by both APC/C(fzy) and APC/C(fzr); fzy has a KEN box and is degraded by APC/C(fzr) only. We characterized the degradation of substrates with swapped d-boxes. Cyclin B1 with KEN was degraded by APC/C(fzr) only. Fzy with RXXL could be degraded by APC/C(fzy) and APC/C(fzr). Interestingly, APC/C(fzy)- but not APC/C(fzr)-specific degradation is highly dependent on the location of RXXL. We studied degradation of tagged substrates in real time and observed that APC/C(fzr) is activated in early G(1). These observations demonstrate how d-box specificities of APC/C(fzy) and APC/C(fzr), and the successive activation of APC/C by fzy and fzr, establish the temporal degradation pattern. Our observations can explain further why some endogenous RXXL substrates are degraded by APC/C(fzy), while others are restricted to APC/C(fzr).
Department of Genetics, Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Amit
A
Zur
Michael
M
Brandeis
D016475:3T3 Cells / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D015703:Antigens, CD; D015820:Cadherins; D064199:Cdc20 Proteins; D064200:Cdh1 Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism*; D019926:Cyclin B / Q000737:chemistry / Q000378:metabolism*; D056744:Cyclin B1; D016193:G1 Phase; D006801:Humans; D008025:Ligases / Q000378:metabolism*; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000502:physiology*; D013379:Substrate Specificity; D013997:Time Factors; D025801:Ubiquitin / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes
D015703:Antigens, CD; C534699:CCNB1 protein, human; C513384:CDH1 protein, human; D015820:Cadherins; C534700:Ccnb1 protein, mouse; D064199:Cdc20 Proteins; C577491:Cdc20 protein, mouse; D064200:Cdh1 Proteins; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; C577584:FZR1 protein, human; C577585:Fzr1 protein, mouse; D046911:Macromolecular Substances; D011506:Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; C577488:CDC20 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D008025:Ligases