Papers - NAKANO Shuuichi
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Comprehensive analysis of stability and variability of DNA minimal i-motif structures Invited Reviewed
K. Ashida, A. Kitabayashi, K. Nishiyama, and S. Nakano
Molecules 30 1831 2025.4
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Inhibition of RNA phosphodiester backbone cleavage in the presence of organic cations of different sizes Invited Reviewed International journal
S. Yoshioka, A. Doi, and S. Nakano
ChemBioChem 25 ( 13 ) e202400276 2024.5
Joint Work
Authorship：Last author, Corresponding author Publisher：Wiley
Living cells contain various types of organic cations that may interact with nucleic acids. In order to understand the nucleic acid–binding properties of organic cations of different sizes, we investigated the ability of simple organic cations to inhibit the RNA phosphodiester bond cleavage promoted by Mg2+, Pb2+, and RNA-cleaving serum proteins. Kinetic analysis using chimeric DNA–RNA oligonucleotides showed that the cleavage at ribonucleotide sites was inhibited in the presence of monovalent cations comprising alkyl chains or benzene rings. The comparison of the cleavage rates in the presence of quaternary ammonium and phosphonium ions indicated that the steric hindrance effect of organic cations on their binding to the RNA backbone is significant when the cation size is larger than the phosphate–phosphate distance of a single-stranded nucleic acid. The cleavage inhibition was also observed for ribonucleotides located in long loops but not in short loops of oligonucleotide structures, indicating less efficient binding of bulky cations to structurally constrained regions. These results reveal the unique nucleic acid–binding properties of bulky cations distinct from those of metal ions.
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Basic protein- and peptide-induced stabilization of long-loop DNA G-quadruplexes Reviewed International journal
K. Tanabe, K. Miyazaki, H. Umeno, M. Takemoto, and S. Nakano
Biochimie 219 110 - 117 2024.4
Joint Work
Authorship：Last author, Corresponding author Publisher：Elsevier
The human genome contains many G-quadruplex-forming sequences, including sequences containing long single-stranded loops that are believed to be unfavorable for G-quadruplex formation. The intracellular environment of biological cells is crowded with proteins with charged surfaces. Understanding the effects of protein-rich environments is important for understanding the formation of G-quadruplexes in an intracellular environment. In this study, we investigated the structural stability of DNA G-quadruplexes in the presence of several types of globular proteins (lysozyme, cytochrome c, bovine serum albumin, myoglobin, histone proteins, and serum proteins), unstructured polypeptides (protamine and poly-l-lysine), and oligopeptides (RGG/RG-domain peptides and short repeated peptides). Thermal melting studies of G-quadruplex-forming oligonucleotides derived from the human telomeric repeat sequence revealed that environments containing high concentrations of proteins and peptides differently affected the G-quadruplex stability according to their loop lengths. We found that weak electrostatic interactions of G-quadruplex loops with basic proteins and peptides improved the stability of long-loop G-quadruplexes and the interactions were strengthened under crowded conditions simulated by dextran. The comparison of the effects of different types of proteins and peptides indicated that excluded volume interactions and structural flexibility of both DNA and polypeptide chains influenced the efficiency of their interactions. This study provides insights into long-loop G-quadruplex stability in a crowded intracellular environment and the recognition of G-quadruplexes by arginine-rich domains of G-quadruplex-binding proteins.
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Evaluation of thermal stability of DNA oligonucleotide structures embedded in hydrogels Invited Reviewed International journal
D. Yamaguchi, M. Yoshida, S. Nakano
DNA 2 ( 4 ) 302 - 313 2022.12
Joint Work
Authorship：Last author, Corresponding author Publisher：MDPI
Understanding the self-assembly and hybridization properties of DNA oligonucleotides in confined spaces can help to improve their applications in biotechnology and nanotechnology. This study investigates the effects of spatial confinement in the pores of hydrogels on the thermal stability of DNA oligonucleotide structures. The preparation of oligonucleotides embedded in agarose gels was simple, whereas the preparation of oligonucleotides embedded in polyacrylamide gels was required to remove unpolymerized monomers. In the latter case, a method for rehydrating a washed dry gel with a buffer solution containing oligonucleotides was developed. Fluorescence measurements of oligonucleotides bearing fluorescent probes revealed no significant influence of the internal environment of the gel pores on the stability of DNA duplex, hairpin, and G-quadruplex structures. Moreover, the effects of poly(ethylene glycol) on the stability of DNA structures in the gels were similar to those in solutions. It is likely that the oligonucleotides are not strongly constrained in the gels and may be preferentially located in a water-rich environment in the gel matrix. The gel preparation was also applied to the assessment of the stability of DNA structures under the conditions of a reduced number of water molecules. The studies using hydrogels provide insights into the ability of self-assembly and hybridization of oligonucleotides in confined environments and under low-water-content conditions.
DOI： 10.3390/dna2040021
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Evaluation of weak interactions of proteins and organic cations with DNA duplex structures Reviewed International journal
R. Morimoto, M. Horita, D. Yamaguchi, H. Nakai, and S. Nakano
Biophys. J. 121 ( 15 ) 2873 - 2881 2022.8
Joint Work
Authorship：Last author, Corresponding author Publisher：Cell Press
Molecular interactions and reactions in living cells occur with high background concentrations of organic compounds including proteins. Uncharged water-soluble polymers are commonly used cosolutes in studies on molecular crowding, and most studies argue about the effects of intracellular crowding based on results obtained using polymer cosolutes. Further investigations using protein crowders and organic cations are important in understanding the effects of cellular environments on nucleic acids with negatively charged surfaces. We assessed the effects of using model globular proteins, serum proteins, histone proteins, structurally flexible polypeptides, di- and polyamines, and uncharged polymers. Thermal stability analysis of DNA oligonucleotide structures revealed that unlike conventional polymer cosolutes, basic globular proteins (lysozyme and cytochrome c) at high concentrations stabilized long internal and bulge loop structures but not fully matched duplexes. The selective stabilization of long loop structures suggests preferential binding to unpaired nucleotides in loops through weak electrostatic interactions. Furthermore, the ability of the proteins to stabilize the loop structures was enhanced under macromolecular crowding conditions. Remarkably, the effects of basic proteins on the stability of fully matched duplexes were dissimilar to those of basic amino-acid-rich polypeptides and polyamines. This study provides new insights into the interaction of nucleic acid structures with organic cations.
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Enhancement of the Catalytic Activity of Hammerhead Ribozymes by Organic Cations. Reviewed International journal
Shu-Ichi Nakano, Hirofumi Yamashita, Naoki Sugimoto
ChemBioChem 22 ( 17 ) 2721 - 2728 2021.7
Joint Work
Authorship：Lead author, Corresponding author
Catalytic turnover is important for the application of ribozymes to biotechnology. However, the turnover is often impaired because of the intrinsic high stability of base pairs with cleaved RNA products. Here, organic cations were used as additives to improve the catalytic performance of hammerhead ribozyme constructs that exhibit different kinetic behaviors. Kinetic analysis of substrate cleavage demonstrated that bulky cations, specifically tetra-substituted ammonium ions containing pentyl groups or a benzyl group, have the ability to greatly increase the turnover rate of the ribozymes. Thermal stability analysis of RNA structures revealed that the bulky cations promote the dissociation of cleaved products and refolding of incorrectly folded structures with small disruption of the catalytic structure. The use of bulky cations is a convenient method for enhancing the catalytic activity of hammerhead ribozymes, and the approach may be useful for advancing ribozyme technologies.
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Controlling interfacial ion-transport kinetics using polyelectrolyte membranes for additive- and effluent-free, high-performance electrodeposition Reviewed International journal
K. Akamatsu, S. Nakano, K. Kimura, Y. Takashima, T. Tsuruoka, H. Nawafune, Y. Sato, J. Murai, and H. Yanagimoto
ACS Appl. Mater. Interfaces 13 ( 11 ) 13896 - 13906 2021.3
Joint Work
Publisher：ACS Publications
The development of high-performance, environmentally friendly electrodeposition processes is critical for emerging coating technologies because current technologies use highly complex baths containing metal salts, supporting electrolytes, and various kinds of organic additives, which are problematic from both environmental and cost perspectives. Here, we show that a 200 μm-thin polyelectrolyte membrane sandwiched between electrodes effectively concentrates metal ions through interfacial penetration, which increases the conductance between the electrodes to 0.30 S and realizes solid-state electrodeposition that produces no mist, sludge, or even waste effluent. Both, experimental results and theoretical calculations, reveal that electrodeposition is controlled by ion penetration at the solution/polyelectrolyte interface, providing an intrinsically different ion-transport mechanism to that of conventional diffusion-controlled electrodeposition. The setup, which includes 0.50 mol L–1 copper sulfate and no additives, delivers a maximum current density of 300 mA cm–2, which is nearly fivefold higher than that of a current commercial plating bath containing organic additives.
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Hydroxyl groups in cosolutes regulate the G-quadruplex topology of telomeric DNA Reviewed
H. Tateishi-Karimata, D. Banerjee, T. Ohyama, S. Matsumoto, D. Miyoshi, S. Nakano, and N. Sugimoto
525 177 - 183 2020.2
Joint Work
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Bulky cations greatly increase the turnover of a native hammerhead ribozyme Reviewed
S. Nakano, H. Yamashita, K. Tanabe, N. Sugimoto
9 35820 - 35824 2019.11
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Stabilization of DNA loop structures by large cations Reviewed
S. Nakano, T. Ayusawa, Y. Tanino, N. Sugimoto
J. Phys. Chem. B 123 7687 - 7694 2019.8
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Thermal stability and conformation of DNA and proteins under the confined condition in the matrix of hydrogels
S. Nakano, D. Yamaguchi, and N. Sugimoto
Mol. Biol. Rep. ４5 403 - 411 2018.4
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Modulation of the ribozyme and deoxyribozyme activities using tetraalkylammonium ions Reviewed
S. Nakano, T. Watabe, and N. Sugimoto
ChemPhysChem 18 ( 24 ) 3614 - 3619 2017.12
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Catalytic activities of ribozymes and DNAzymes in water and mixed aqueous media Invited Reviewed
S. Nakano, M. Horita, M. Kobayashi, and N. Sugimoto
Catalysis 7 ( 12 ) 355 - 348 2017.11
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DNA G-wire formation using an artificial peptide is controlled by protease activity Reviewed
K. Usui, A. Okada, S. Sakashita, M. Shimooka, T. Tsuruoka, S. Nakano, D. Miyoshi, T. Mashima, M. Katahira, and Y. Hamada
Molecules 22 ( 11 ) 1991 - 2002 2017.11
Joint Work
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Newly characterized interaction stabilizes DNA structure: oligoethylene glycols stabilize G-quadruplexes CH–π interactions Reviewed
H. Tateishi-Karimata, T. Ohyama, T. Muraoka, P. Podbevsek, A. M. Wawro, S. Tanaka, S. Nakano, K. Kinbara, J. Plavec, N. Sugimoto
Nucleic Acids Res. 45 7021 - 7030 2017.7
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Model studies of the effects of intracellular crowding on nucleic acid interactions Invited Reviewed
13 32 - 41 2016.12
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Effects of trimethylamine N-oxide and urea on DNA duplex and G-quadruplex Reviewed
Y. Ueda, Y. Zouzumi, A. Maruyama, S. Nakano, N. Sugimoto, and D. Miyoshi
Sci. Tech. Adv. Mat. 17 753 - 759 2016.11
Joint Work
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Thermal stability of RNA structures with bulky cations in mixed aqueous solutions Reviewed
S. Nakano, Y. Tanino, H. Hirayama, and N. Sugimoto
Biophys. J. 111 1350 - 1360 2016.10
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Local thermodynamics of the water molecules around single- and double-stranded DNA studied by grid inhomogeneous solvation theory Reviewed
M. Nakano, H. Tateishi-Karimata, S. Tanaka, F. Tamab, O. Miyashita, S. Nakano, and N. Sugimoto
Chem. Phys. Lett. 660 ( 1 ) 250 - 255 2016.9
Joint Work
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Use of a ureido-substituted deoxycytidine module for DNA assemblies Invited Reviewed
S. Nakano, H. Oka, M. Fujii, and N. Sugimoto
Nucleosides, Nucleotides and Nucleic Acids 35 ( 7 ) 370 - 378 2016.5