• Title/Summary/Keyword: Imino proton exchange

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Structural and Dynamic Studies of the Central Segments in the Self-complementary Decamer DNA Duplexes d(ACGTATACGT)2 and d(ACGTTAACGT)2

  • Park, Jin-Young;Lee, Joon-Hwa;Choi, Byong-Seok
    • BMB Reports
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    • v.31 no.1
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    • pp.89-94
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    • 1998
  • The structures of the self-complementary decamer duplexes, $d(ACGTATACGT)_2$ (TATA-duplex) and $d(ACGTTAACGT)_2$, (TTAA-duplex) has been obtained in solution by proton NMR spectroscopy and restrained molecular dynamics. The duplexes are essentially B-type, with distortions apparent at the TATA and TTAA steps. Theses distortions and their effects on dynamics have been investigated by the measurement of imino proton exchange time of the base-pairs. The unusual opening kinetics of central A T base-pairs could be correlated to the abnormal structural properties of the corresponding sequences.

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NMR Study of Consensus DNA-binding Site for Arabidopsis thaliana Class I Transcription Factor AtTCP1

  • Choi, Yong-Geun;Kim, Hee-Eun;Lee, Joon-Hwa
    • Journal of the Korean Magnetic Resonance Society
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    • v.17 no.2
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    • pp.76-80
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    • 2013
  • The TCP domain is a DNA-binding domain present in plant transcription factors and has a similar structural feature to the bHTH motif of eukaryotic transcription factors. The imino proton exchange study has been performed for the DNA duplex containing the consensus DNA-binding site for the AtTCP11 transcription factor. The first two base pairs in the consensus 5'-GTGGG-3' sequence are relatively very unstable but lead to greater stabilization of the neighboring two G C base pairs. These unique dynamic features of the five base pairs in the consensus DNA sequence might play crucial roles in the effective DNA binding of the AtTCP11 protein.

Mg2+-dependency of the Helical Conformation of the P1 Duplex of the Tetrahymena Group I Ribozyme

  • Lee, Joon-Hwa
    • Bulletin of the Korean Chemical Society
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    • v.29 no.10
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    • pp.1937-1940
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    • 2008
  • The P1 duplex of Tetrahymena group I ribozyme is the important system for studying the conformational changes in folding of ribozyme. The formation of the P1 duplex between IGS and substrate RNA and the catalytic activity of ribozyme require a variety of metal ions such as $Mg^{2+}$ and $Mn^{2+}$. In order to investigate the effect of the $Mg^{2+}$ concentration on the conformation of the P1 duplex, the NMR study was performed as a function of $Mg^{2+}$ concentration. This study revealed that the less stable AU-rich region formed duplex at $50{^{\circ}C}$ under high $Mg^{2+}$ concentration condition but melts out under low $Mg^{2+}$ concentration condition. It was also found that in the active conformation under 10 mM $MgCl_2$ condition, the unstable central G${\cdot}$U wobble pair maintains the significant base pairing up to $50{^{\circ}C}$. This study provides the information of the unique feature of the P1 duplex structure and the roll of $Mg^{2+}$ ion on the formation of the active conformation.