Taiichi Sakamoto

Learn More
BACKGROUND Hepatitis delta virus (HDV) ribozymes cleave RNA in the presence of divalent metal ions. We have previously elucidated the solution conformation of a minimized trans-acting HDV ribozyme and obtained evidence by NMR study that an Mg2+ ion binds to a site close to the cleavage site. RESULTS We examined two ribozyme systems: a pre-cleavage complex(More)
Potential applications for functional RNAs are rapidly expanding, not only to address functions based on primary nucleotide sequences, but also by RNA aptamer, which can suppress the activity of any target molecule. Aptamers are short DNA or RNA folded molecules that can be selected in vitro on the basis of their high affinity for a target molecule. Here,(More)
Minimized trans-acting HDV ribozyme systems consisting of three (Rz-3) and two (Rz-2) RNA strands were prepared and their folding conformations were analyzed by NMR spectroscopy. The guanosine residues in one of the enzyme components of Rz-3 were labeled with 13C and 15N. Imino proton signals were assigned by analysis of NOESY and HSQC spectra. The results(More)
Aptamers are short single-stranded nucleic acids with high affinity to target molecules and are applicable to therapeutics and diagnostics. Regardless of an increasing number of reported aptamers, the structural basis of the interaction of RNA aptamer with proteins is poorly understood. Here, we determined the 2.15 Å crystal structure of the Fc fragment of(More)
The eel long interspersed element (LINE) UnaL2 and its partner short interspersed element (SINE) share a conserved 3' tail that is critical for their retrotransposition. The predicted secondary structure of the conserved 3' tail of UnaL2 RNA contains a stem region with a putative internal loop. Deletion of the putative internal loop region abolishes UnaL2(More)
Assembly of the human signal recognition particle (SRP) requires SRP19 protein to bind to helices 6 and 8 of SRP RNA. In the present study, structure of a 29-mer RNA composing the SRP19 binding site in helix 6 was determined by NMR spectroscopy. The two A:C mismatches were continuously stacked to each other and formed wobble type A:C base pairs. The GGAG(More)
A high affinity RNA aptamer (APT58, 58 nt long) against mammalian initiation factor 4A (eIF4A) requires nearly its entire nucleotide sequence for efficient binding. Since splitting either APT58 or eIF4A into two domains diminishes the affinity for each other, it is suggested that multiple interactions or a global interaction between the two molecules(More)
The NMR structure of a 12-mer RNA derived from the helix 6 of SRP RNA from Pyrococcus furiosus, whose loop-closing base pair is U.G, was determined, and the structural and thermodynamic properties of the RNA were compared with those of a mutant RNA with the C:G closing base pair. Although the structures of the two RNAs are similar to each other and adopt(More)
AML1/RUNX1 is an essential transcription factor involved in the differentiation of hematopoietic cells. AML1 binds to the Runt-binding double-stranded DNA element (RDE) of target genes through its N-terminal Runt domain. In a previous study, we obtained RNA aptamers against the AML1 Runt domain by systematic evolution of ligands by exponential enrichment(More)
AML1 (RUNX1) is a key transcription factor for hematopoiesis that binds to the Runt-binding double-stranded DNA element (RDE) of target genes through its N-terminal Runt domain. Aberrations in the AML1 gene are frequently found in human leukemia. To better understand AML1 and its potential utility for diagnosis and therapy, we obtained RNA aptamers that(More)