| Co-Investigator(Kenkyū-buntansha) |
ヴィンタース ベルガー ウィーン大学, ガン研究所, 準教授
スティルマン デビットJ ユタ大学, 細胞ウイルス分子生物学, 準教授
クーパー ジョンA ワシントン大学, 医学部, 準教授
WINTERSBERGER Ulrike University of Vienna, Inst.Tumorbiol.Cencer Res., Associated Professor
COOPER John A. Washington University School of Medicine, Associate Professor
STILLMAN David J. University of Utah Health Science Center, Associated Professor
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| Research Abstract |
Recently various actin-related proteins, which show moderate similarity to conventional actins, have been reported, suggesting that actin family is much more diverse than it had been thought. ACT3 in Saccharomyces cerevisiae codes an actin-related protein and is essential for viability. Act3p is an novel actin-family protein in terms of its nuclear localization. According to sequence comparison, the basal core structure of conventional actin may well be conserved in Act3p. On the other hand, Act3p contains two unique hydrophilic segments compared with other actin family proteins. One of the unique segments contains a putative nuclear-targeting signal. The other is abundant in charged amino acids and predicted to form a loop-like structure protruded from surface.
Little is known about function of Act3p in nucleus, however, we got some results suggesting that Act3p was associated with chromatin. For instance, Act3p is released from isolated nuclei by treatment with salt or by digestion of chromatin with DNaseI.In addition, it was shown that point-mutations of ACT3 cause epigenetic effects on both chromatin structure and transcription of some genes in yeast.
It was thought that the unique segments of Act3p would be involved in its distinct function from other actin-family Proteins and we tried to identify proteins which interact with the segments. In the course of the research, we perfbrmed far-western blotting with a labeled peptide containing one of the segments and two-hybrid analysis. As a result, it was shown that the peptide bound mainly to core histones in vitro. In addition, protein-complex (es) containing both Act3p and core histones was isolated from nuclear extract using histidine-tagged Act3p and an anti-Act3p antibody, suggesting that Act3p interacts with core histones in vivo.
These findings show that Act3p is involved in transcriptional regulation through the change and/or maintenance of chromatin structure.
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