Characterization of Rad6 from a higher plant, rice (Oryza sativa L.) and its interaction with Sgt1, a subunit of the SCF ubiquitin ligase complex.
We report here the existence of interactions between a ubiquitin-conjugating enzyme, Rad6, from rice, Oryza sativa L. cv. Nipponbare (OsRad6), and Sgt1 (OsSgt1), a novel subunit of the SCF ubiquitin ligase complex. Rad6 is not only related to post-replicational repair but also to the proteasome system, while Sgt1 has a function in kinetochore assembly. The relationship between the two is unexpected, but of great interest. The open reading frames of OsRad6 and OsSgt1 encode predicted products of 152 and 367 amino acid residues, respectively, with molecular weights of 17.3 and 40.9kDa. Two-hybrid and pull-down analyses indicated that OsRad6 binds to OsSgt1, and transcripts of both OsRad6 and OsSgt1 were found to be strongly expressed only in the proliferating tissues such as the shoot apical meristem, suggesting that their expression is cell cycle-dependent. The amount of the Rad6 mRNA in cultured cells increased rapidly after division was halted, and mRNA levels of Rad6 and Sgt1 were induced by UV- and DNA-damaging agents such as MMS or H(2)O(2). The Rad6 pathway for repair or the proteasome system may thus require Sgt1 as ubiquitin-conjugating enzyme.
Yamamoto
Taichi
T
Department of Applied Biological Science, Faculty of Science and Technology, Science University of Tokyo, 2641 Yamazaki, Noda-shi, 278-8510 Chiba-ken, Japan.
Mori
Yoko
Y
Ishibashi
Toyotaka
T
Uchiyama
Yukinobu
Y
Sakaguchi
Norihiro
N
Furukawa
Tomoyuki
T
Hashimoto
Junji
J
Kimura
Seisuke
S
Sakaguchi
Kengo
K
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D018076:DNA, Complementary / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D015151:Immunoblotting; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism; D016366:Open Reading Frames; D012275:Oryza / Q000378:metabolism*; D010802:Phylogeny; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D021122:Protein Subunits; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014018:Tissue Distribution; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry* / Q000235:genetics*; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*; D014466:Ultraviolet Rays
D018076:DNA, Complementary; D009097:Multienzyme Complexes; D021122:Protein Subunits; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin; D044763:Ubiquitin-Conjugating Enzymes; D043743:Ubiquitin-Protein Ligase Complexes; D044843:SKP Cullin F-Box Protein Ligases; D005982:Glutathione Transferase; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex