Masami Otsuka

Identification of TIFA as an Adapter Protein That Links Tumor Necrosis Factor Receptor-associated Factor 6 (TRAF6) to Interleukin-1 (IL-1) Receptor-associated Kinase-1 (IRAK-1) in IL-1 Receptor Signaling

Tumor necrosis factor receptor-associated factor 6 (TRAF6) transduces signals from members of the Toll/interleukin-1 (IL-1) receptor family by interacting with IL-1 receptor-associated kinase-1 (IRAK-1) after IRAK-1 is released from the receptor-MyD88 complex upon IL-1 stimulation. However, the molecular mechanisms underlying regulation of the IRAK-1/TRAF6 interaction are largely unknown. We have identified TIFA, a TRAF-interacting protein with a forkhead-associated (FHA) domain. The FHA domain is a motif known to bind directly to phosphothreonine and phosphoserine. In transient transfection assays, TIFA activates NFκΒ and c-Jun amino-terminal kinase. However, TIFA carrying a mutation that abolishes TRAF6 binding or mutations in the FHA domain that are known to abolish FHA domain binding to phosphopeptide fails to activate NFκΒ and c-Jun amino-terminal kinase. TIFA, when overexpressed, binds both TRAF6 and IRAK-1 and significantly enhances the IRAK-1/TRAF6 interaction. Furthermore, analysis of endogenous proteins indicates that TIFA associates with TRAF6 constitutively, whereas it associates with IRAK-1 in an IL-1 stimulation-dependent manner in vivo. Thus, TIFA is likely to mediate IRAK-1/TRAF6 interaction upon IL-1 stimulation.

DNA-bleomycin interaction: Nucleotide sequence-specific binding and cleavage of DNA by bleomycin

Biosynthetic intermediates and synthetic analogues of bleomycin (BLM) have been investigated for their metal binding, dioxygen activation, and DNA cleavage. Molecular O2 was activated by the Fe(II) complex of a synthetic model ligand. Nucleotide sequence specificities in DNA cleavage by the BLM-Fe(II) and deglyco-BLM-Fe(II) complexes were almost identical. It has been shown that (1) the β-aminoalanine-pyrimidine-β-hydroxyhistidine portion of BLM is essential for the metal binding and dioxygen activation and (2) the bithiazole moiety contributes to the specific binding to guanine base of DNA.

Man-designed bleomycins: Significance of the binding sites as enzyme models and of the stereochemistry of the linker moiety

Abstract Comparison of the DNA cleavage activity of man-designed bleomycins demonstrates that belomycins are small enzymes comprised of a catalytic site and a binding site. The linker moiety is shown to be significant for DNA binding, and inversion of its stereochemistry results in a dramatic decrease in the DNA-cleaving efficiency. One of the man-designed BLMs shows excellent cytotoxicity against L1210.

Man-designed bleomycins. synthesis of dioxygen activating molecules and a DNA cleaving molecule based on bleomycin-Fe(II)-02 complex

Abstract A synthetic model for the metal binding site of bleomycin with a 4-methoxypyridine nucleus and a tert -butyl group is shown to be comparable to bleomycin in terms of dioxygen activation. This model ligand is coupled with a DNA affinity moiety, tetrapeptide S, to afford a mandesigned bleomycin which exhibits potent DNA cleaving activity in vitro .

Total synthesis of deglyco-bleomycin A2

Abstract Deglyco-bleomycin A2, the aglycon of bleomycin A2, has been synthesized for the first time.

Synthetic models for the transition metal binding site of bleomycin: remarkable improvement of dioxygen activating capability

Abstract Model compounds for the metal binding site of bleomycin with a CH2 CONH2 group (PYML-3) or a tert -butyl group (PYML-4) as steric environmental factors are synthesized. These exhibit metal binding properties similar to those of bleomycin. In particular, PYML-4 shows oxygen activation up to 71 % of that of bleomycin.

Transition-metal binding site of bleomycin. A synthetic analogue equivalent to bleomycin in activating molecular oxygen

Abstract A synthetic model compound for the metal binding site of bleomycin (PYML-6) with an electron donating methoxy substituent showed remarkably efficient oxygen activation comparable to bleomycin.

Transition-metal binding site of bleomycin. A remarkably efficient dioxygen-activating molecule based on bleomycin-Fe(II) complex

Abstract A synthetic model compound for the metal binding site of bleomycin (PYML-4) with a tert -butyl group as a steric environmental factor showed improved oxygen-activation up to 71% of that of bleomycin.

Stereoselective synthesis of (2s,3s,4r)-4-amino-3-hydroxy-2-methyl-pentanoic acid, an amino acid constituent of bleomycin, by aldold condensation)☆

Abstract (2S,3S,4R)-4-Amino-3-hydroxy-2-methylpentanoic acid, a novel amino acid constituent of bleomycin, has been synthesized stereoselectively through aldol condensation of (R)-2-aminopropionaldehyde derivatives and E-vinyloxyboranes.

CC bond formation from schiff base and vinyloxyborane: Synthesis of β-amino acid derivatives

Abstract An efficient methodology for the preparation of β-amino acid derivatives ( 3 ) by CC bond formation from Schiff bases ( 1 ) and vinyloxyborane ( 2 ) and their utilization in the synthesis of the pyrimidine moiety ( 3f ) of bleomycin are described.