Cul8/Rtt101 forms a variety of protein complexes that regulate DNA damage response and transcriptional silencing.
The budding yeast, Saccharomyces cerevisiae, has three cullin proteins, which act as platforms for Cullin-based E3 ubiquitin ligases. Genetic evidence indicates that Cul8, together with Mms1, Mms22, and Esc4, is involved in the repair of DNA damage that can occur during DNA replication. Cul8 is thought to form a complex with these proteins, but the composition and the function of Cul8-based E3 ubiquitin ligases remain largely uncharacterized. Herein, we report a comprehensive biochemical analysis of Cul8 complexes. Cul8 was found to form a Cul8-Mms1-Mms22-Esc4 complex under physiological conditions, with Mms1 bridging Cul8 and Mms22 and Mms22 bridging Mms1 and Esc4. Domain analysis demonstrated that the N-terminal region of Mms1 and the C-terminal region of Mms22 are required for the Mms1-Mms22 interaction, whereas the N-terminal region of Mms22 is required for the Mms22-Esc4 interaction. We also found other Cul8-Mms1-binding proteins Ctf4, Esc2, and Orc5 using yeast two-hybrid screening. Esc4 and Ctf4 bound to Mms22 directly and bound to Cul8-Mms1 in the presence of Mms22, whereas Esc2 and Orc5 interacted with both Cul8 and Mms1, independently. We found that Cul8, Mms1, and Mms22 participated in the regulation of transcriptional silencing of yeast telomeres. These results suggest that Cul8-Mms1, as part of various protein complexes, is involved in the regulation of chromatin metabolism.
Mimura
Satoru
S
Division of Biological Science, Graduate School of Science, Nagoya University Chikusa-ku, Nagoya 464-8602.
Yamaguchi
Tsuyoshi
T
Division of Biological Science, Graduate School of Science, Nagoya University Chikusa-ku, Nagoya 464-8602.
Ishii
Satoru
S
Division of Biological Science, Graduate School of Science, Nagoya University Chikusa-ku, Nagoya 464-8602.
Noro
Emiko
E
Faculty of Advanced Life Science, Hokkaido University, Kita-21, Nishi-11, Sapporo, Hokkaido 001-0021, Japan.
Katsura
Tomoya
T
Division of Biological Science, Graduate School of Science, Nagoya University Chikusa-ku, Nagoya 464-8602.
Obuse
Chikashi
C
Faculty of Advanced Life Science, Hokkaido University, Kita-21, Nishi-11, Sapporo, Hokkaido 001-0021, Japan.
Kamura
Takumi
T
Division of Biological Science, Graduate School of Science, Nagoya University Chikusa-ku, Nagoya 464-8602. Electronic address: z47617a@nucc.cc.nagoya-u.ac.jp.
D002843:Chromatin / Q000378:metabolism; D044842:Cullin Proteins / Q000378:metabolism*; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D008954:Models, Biological; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D016615:Telomere / Q000648:ultrastructure; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
C078338:CTF4 protein, S cerevisiae; D002843:Chromatin; D044842:Cullin Proteins; D004268:DNA-Binding Proteins; C530190:Mms1 protein, S cerevisiae; C497133:Mms22 protein, S cerevisiae; C476451:RTT101 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins