Yasunori Funabashi

A new anti-MRSA dipeptide, TAN-1057 A

Abstract The chemical structure of a new dipeptide antibiotic, TAN-1057 A, isolated from the broth filtrate of Flexibacter sp. PK-74 was determined to be (3′S, 5S)-5-[N-methyl-N-(3′-amino-6′-guanidinohexanoyl)amino]5,6-dihydro-2-ureido-4(1H)-pyrimidone. The antibiotic was specifically active against staphylococcus species including methicillin-resistant strains.

A novel amino acid antibiotic tan-950

Abstract A novel antifungal antibiotic, TAN-950 A, was isolated from the culture filtrate of Streptomyces platensis A-136. Its structure was determined to be (S)-2-amino-3-(isoxazolin-5-on-4-yl)-propanoic acid. Minor components, TAN-950 B, C, D and E, were found to be present in an equilibrium mixture containing TAN-950 A. Their structures were determined from spectral analyses. X-ray crystallographic analysis and synthesis from L-glutamic acid.

ITZ-1, a Client-Selective Hsp90 Inhibitor, Efficiently Induces Heat Shock Factor 1 Activation

ITZ-1 is a chondroprotective agent that inhibits interleukin-1beta-induced matrix metalloproteinase-13 (MMP-13) production and suppresses nitric oxide-induced chondrocyte death. Here we describe its mechanisms of action. Heat shock protein 90 (Hsp90) was identified as a specific ITZ-1-binding protein. Almost all known Hsp90 inhibitors have been reported to bind to the Hsp90 N-terminal ATP-binding site and to simultaneously induce degradation and activation of its multiple client proteins. However, within the Hsp90 client proteins, ITZ-1 strongly induces heat shock factor-1 (HSF1) activation and causes mild Raf-1 degradation, but scarcely induces degradation of a broad range of Hsp90 client proteins by binding to the Hsp90 C terminus. These results may explain ITZ-1s inhibition of MMP-13 production, its cytoprotective effect, and its lower cytotoxicity. These results suggest that ITZ-1 is a client-selective Hsp90 inhibitor.