論文 - 宮地　まり

S1A03クロマチンシャペロンの分子機能

永田 恭介, Gyurcsik Bela, 春木 宏人, 宮地-山口 まり, 奥脇 暢, 高橋 剛, 三原 久和

生物物理   41   S1   2001年

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記述言語：日本語   出版者・発行元：一般社団法人 日本生物物理学会  

DOI： 10.2142/biophys.41.S1_3

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Sperm chromatin decondensation by template activating factor I through direct interaction with basic proteins 査読

K Matsumoto, K Nagata, M Miyaji-Yamaguchi, A Kikuchi, M Tsujimoto

MOLECULAR AND CELLULAR BIOLOGY   19 ( 10 )   6940 - 6952   1999年10月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC MICROBIOLOGY  

Template activating factor I (TAF-I) was originally identified as a host factor required for DNA replication and transcription of adenovirus genome complexed with viral basic proteins. Purified TAF-I was shown to bind to core histones and stimulate transcription from nucleosomal templates. Human TAF-I consists of two acidic proteins, TAF-I alpha and TAF-I beta, which differ from each other only in their amino-terminal regions. Here, we report that TAF-I decondenses demembraned Xenopus sperm chromatin. Human TAF-I beta has a chromatin decondensation activity comparable to that of NAP-I, another histone binding protein, whereas TAF-I alpha has only a weak activity. Analysis of molecular mechanisms underlying the chromatin decondensation by TAF-I revealed that TAF-I interacts directly with sperm basic proteins. Deletion of the TAF-I carboxyl-terminal acidic region abolishes the decondensation activity. Interestingly, the acidic region itself is not sufficient for decondensation, since an amino acid substitution mutant in the dimerization domain of TAF-I which has the intact acidic region does not support chromatin decondensation. We detected the beta form of TAF-I in Xenopus oocytes and eggs by immunoblotting, and the cloning of its cDNA led us to conclude that Xenopus TAF-I beta also decondenses sperm chromatin. These results suggest that TAF-I plays a role in remodeling higher-order chromatin structure as well as nucleosomal structure through direct interaction with chromatin basic proteins.

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Coiled-coil structure-mediated dimerization of template activating factor-I is critical for its chromatin remodeling activity 査読

M Miyaji-Yamaguchi, M Okuwaki, K Nagata

JOURNAL OF MOLECULAR BIOLOGY   290 ( 2 )   547 - 557   1999年7月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS LTD  

Template activating factor-I (TAF-I)alpha and TAF-I beta have been identified as the host factors that activate DNA replication of the adenovirus genome complexed with viral basic core proteins (Ad core). TAF-I causes a structural change of the Ad core, thereby stimulating not only replication but also transcription from the Ad core DNA in vitro. TAF-I also activates transcription from the reconstituted chromatin consisting of DNA fragments and purified histones through chromatin remodeling. Although the carboxyl-terminal region, which is highly rich in acidic amino acids, is essential for the TAF-I activity, it remains unclear how other parts are involved in its activity. The native TAF-I isolated from HeLa cells exists as either hetero- or homo-oligomer. Here, we have demonstrated by cross-linking assays that most of TAF-I exists as a dimer. Analyses using deletion mutant TAF-I proteins revealed that the amino-terminal region of TAF-I common to both alpha and beta is essential for dimerization. This region is predicted to form a coiled-coil structure. Indeed, mutations disrupting this putative structure abolished the dimerization capability and reduced the TAF-I activity in the Ad core DNA replication assay. Furthermore, we found that TAF-I mutants lacking the acidic tail act in a dominant-negative manner in this assay. These observations strongly suggest that the dimerization of TAF-I is important for its activity. (C) 1999 Academic Press.

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Functional domains of template-activating factor-I as a protein phosphatase 2A inhibitor 査読

S Saito, M Miyaji-Yamaguchi, T Shimoyama, K Nagata

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   259 ( 2 )   471 - 475   1999年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACADEMIC PRESS INC  

Template-Activating Factor-1 (TAF-1) alpha and beta, chromatin remodeling factors, were identified as the stimulatory factor for replication of the adenovirus DNA complexed with viral basic core proteins. Recently, two cellular inhibitors for protein phosphatase 2A (PP2A) have been isolated. One of these inhibitors, designated I-2(PP2A), is a truncated version of TAF-1 beta. Here, it is shown using recombinant TAF-1 proteins that both TAF-1 alpha and beta have the PP2A inhibitor activity. The N-terminal region but not the C-terminal acidic region, the latter of which is essential for the chromatin remodeling activity, is shown to be required for the PP2A inhibitor activity. Roles of TAF-1 alpha- and beta-specific regions, the C-terminal acidic region, and other regions of TAF-1 for the PP2A inhibitor activity are also discussed. (C) 1999 Academic Press.

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NAP-I is a functional homologue of TAF-I that is required for replication and transcription of the adenovirus genome in a chromatin-like structure 査読

H Kawase, M Okuwaki, M Miyaji, R Ohba, H Handa, Y Ishimi, T FujiiNakata, A Kikuchi, K Nagata

GENES TO CELLS   1 ( 12 )   1045 - 1056   1996年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL SCIENCE LTD  

Background: For the activation of replication and transcription from DNA in a chromatin structure, a variety of factors are thought to be needed that alter the chromatin structure. Template activating factor-I (TAF-I) has been identified as such a host factor required for replication of the adenovirus (Ad) genome complexed with viral basic core proteins (Ad core). TAF-I also stimulates transcription from the Ad core DNA.
Results: Using mutant TAF-I proteins, we have demonstrated that the acidic stretch present in the carboxyl terminal region is essential for the stimulation of transcription from the Ad core. A genomic footprinting experiment with restriction endonuclease has revealed that TAF-I causes a structural change in the Ad core. TAP-I has been shown to have significant amino acid similarity to nucleosome assembly protein-I (NAP-I), which is involved in the formation of the chromatin structure. We have shown that TAF-I can be substituted by NAP-I in the activation of the cell-free Ad core transcription system. Two of the tripartite acidic regions and the region homologous to TAF-I in NAP-I are required for the maximal TAF-I activity of NAP-I. Furthermore, TAF-I has been shown to have NAP-I activity, and the acidic region of TAP-I is required for this activity.
Conclusions: Since TAF-I causes the structural change of the Ad core and thereby activates transcription, TAF-I is thought to be one of the proteins which is involved in chromatin remodeling. NAP-I is structurally related to TAF-I and functionally substitutes for TAF-I. Furthermore, TAF-I has NAP-I activity. These observations suggest that this type of molecule has dual functions, possibly by participating in facilitating the assembly of the chromatin structure as well as perturbing the chromatin structure to allow transcription to proceed.

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