研究者詳細 - 日比野　絵美

論文 - 日比野　絵美

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Emi Hibino

生物物理 59 巻 ( 4 ) 頁： 202 - 204 2019年

Identification of heteromolecular binding sites in transcription factors Sp1 and TAF4 using high-resolution nuclear magnetic resonance spectroscopy 査読有り Open Access

Hibino, E; Inoue, R; Sugiyama, M; Kuwahara, J; Matsuzaki, K; Hoshino, M

PROTEIN SCIENCE 26 巻 ( 11 ) 頁： 2280 - 2290 2017年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Protein Science

The expression of eukaryotic genes is precisely controlled by interactions between general transcriptional factors and promoter-specific transcriptional activators. The fourth element of TATA-box binding protein-associated factor (TAF4), an essential subunit of the general transcription factor TFIID, serves as a coactivator for various promoter-specific transcriptional regulators. Interactions between TAF4 and site-specific transcriptional activators, such as Sp1, are important for regulating the expression levels of genes of interest. However, only limited information is available on the molecular mechanisms underlying the interactions between these transcriptional regulatory proteins. We herein analyzed the interaction between the transcriptional factors Sp1 and TAF4 using high-resolution solution nuclear magnetic resonance spectroscopy. We found that four glutamine-rich (Q-rich) regions in TAF4 were largely disordered under nearly physiological conditions. Among them, the first Q-rich region in TAF4 was essential for the interaction with another Q-rich region in the Sp1 molecule, most of which was largely disordered. The residues responsible for this interaction were specific and highly localized in a defined region within a range of 20–30 residues. Nevertheless, a detailed analysis of <sup>13</sup>C-chemical shift values suggested that no significant conformational change occurred upon binding. These results indicate a prominent and exceptional binding mode for intrinsically disordered proteins other than the well-accepted concept of “coupled folding and binding.”.

DOI： 10.1002/pro.3287

Interaction between intrinsically disordered regions in transcription factors Sp1 and TAF4 査読有り Open Access

Hibino, E; Inoue, R; Sugiyama, M; Kuwahara, J; Matsuzaki, K; Hoshino, M

PROTEIN SCIENCE 25 巻 ( 11 ) 頁： 2006 - 2017 2016年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Protein Science

The expression of eukaryotic genes is precisely controlled by specific interactions between general transcription initiation factors and gene-specific transcriptional activators. The general transcription factor TFIID, which plays an essential role in mediating transcriptional activation, is a multisubunit complex comprising the TATA box-binding protein (TBP) and multiple TBP-associated factors (TAFs). On the other hand, biochemical and genetic approaches have shown that the promoter-specific transcriptional activator Sp1 has the ability to interact with one of the components of TFIID, the TBP-associated factor TAF4. We herein report the structural details of the glutamine-rich domains (Q-domains) of Sp1 and TAF4 using circular dichroism (CD) and heteronuclear magnetic resonance (NMR) spectroscopy. We found that the two Q-domains of Sp1 and four Q-domains of TAF4 were disordered under physiological conditions. We also quantitatively analyzed the interaction between the Q-domains of Sp1 and TAF4 by NMR and surface plasmon resonance, and detected a weak but specific association between them. Nevertheless, a detailed analysis of CD spectra suggested that any significant conformational change did not occur concomitantly with this association, at least at the level of the overall secondary structure. These results may represent a prominent and exceptional binding mode for the IDPs, which are not categorized in a well-accepted concept of “coupled folding and binding.”.

DOI： 10.1002/pro.3013

Interaction between isolated transcriptional activation domains of Sp1 revealed by heteronuclear magnetic resonance 査読有り Open Access

Hiramatsu, N; Hibino, E; Matsuzaki, K; Kuwahara, J; Hoshino, M

PROTEIN SCIENCE 21 巻 ( 10 ) 頁： 1481 - 1488 2012年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Protein Science

The promoter-specific transcription factor Sp1 is expressed ubiquitously, and plays a primary role in the regulation of the expression of many genes. Domains A and B located in the N-terminal half of the protein are characterized by glutamine-rich (Q-rich) sequences. These Q-rich domains have been shown to be involved in the interaction between Sp1 and different classes of nuclear proteins, such as TATA-binding protein associated factors. Furthermore, the selfassociation of Sp1 via Q-rich domains is also important for the regulation of transcriptional activity. It has been considered that an Sp1 molecule bound to a "distal" GC-box synergistically interacts with another Sp1 molecule at a "proximal" binding site. Although the formation of multimers via Q-rich domains seems functionally important for Sp1, little is known about the structural and physicochemical nature of the interaction between Q-rich domains. We analyzed the structural details of isolated glutamine-rich B (QB) domains of Sp1 by circular dichroism (CD), analytical ultracentrifugation, and heteronuclear magnetic resonance spectroscopy (NMR). We found the isolated QB domains to be disordered under all conditions examined. Nevertheless, a detailed analysis of NMR spectra clearly indicated interaction between the domains. In particular, the C-terminal half was responsible for the self-association. Furthermore, analytical ultracentrifugation demonstrated weak but significant interaction between isolated QB domains. The self-association between QB domains would be responsible, at least in part, for the formation of multimers by full-length Sp1 molecules that has been proposed to occur during transcriptional activation. © 2012 The Protein Society.

DOI： 10.1002/pro.2137

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