Solution structures of the trihelix DNA-binding domains of the wild-type and a phosphomimetic mutant of Arabidopsis GT-1: mechanism for an increase in DNA-binding affinity through phosphorylation.

GT-1 is a plant transcription factor that binds to one of the cis-acting elements, BoxII, which resides within the upstream promoter region of light-responsive genes. GT-1 was assumed to act as a molecular switch modulated through Ca(2+)-dependent phosphorylation/dephosphorylation in response to light signals. It was shown previously that the phosphorylation of threonine 133 in the DNA-binding domain (DBD) of GT-1 results in enhancement of the BoxII-binding activity.

Structure of RNA aptamer complexed with an RNA-binding peptide of Tat with aid of residue-specific 13C, 15N labeling.

An RNA aptamer containing two binding sites of HIV Tat exhibits extremely high affinity to Tat. We have determined the structure of the aptamer complexed with an RNA-binding peptide of Tat. The analysis was made feasible by the use of several peptides in which a single arginine residue was specifically 13C, 15N-labeled.

Structure, stability and application to functional DNA/RNA of unique quadruplex.

We have developed a direct and unambiguous method for discrimination of intra- and intermolecular hydrogen bonds in a symmetric multimer. The method was applied to a symmetric dimer of d(GGAGGAGGAGGA) (GGA 12-mer) and has provided decisive information on its multimeric architecture. Then, the values for scalar couplings across hydrogen bonds for G:G and G:A base pairs in the G(:A):G(:A):G(:A):G heptad formed by GGA 12-mer were determined.