Akira Someya

Interaction of anthracycline antibiotics with actin and heavy meromyosin.

Abstract For the purpose of elucidating the biochemical mechanism of anthracycline cardiomyopathy, the interaction with actin and heavy meromyosin (HMM) was studied. HMM and acto-HMM Mg2+-ATPase reactions were inhibited by daunorubicin and adriamycin; but not significantly by aclacinomycin A. The three antibiotics induced G-actin polymerization. Difference absorption spectra showed a direct interaction of adriamycin or aclacinomycin A with actin or HMM. Equilibrium dialysis and spectrofluorometric studies indicated that actin monomer possesses one binding site for adriamycin or aclacinomycin A with the same order of association constants (1.4 – 7.2 × 104 M−1). Adriamycin exhibited significantly higher affinity for HMM than aclacinomycin A.

Inhibition of influenza virus AWSN replication by a trypsin inhibitor, 6-amidino-2-naphthyl p-guanidinobenzoate

A trypsin inhibitor, 6-amidino-2-naphthyl p-guanidinobenzoate (FUTHAN) reduced both the number and size of plaques of influenza virus A/WSN/33 (H1N1) that can grow without trypsin treatment in MDCK cells. The resulting virus particles with uncleaved hemagglutinin (HA) in the presence of FUTHAN was activated to produce infectious virions by trypsin treatment. Uncleaved HA of WSN virus grown in the presence of FUTHAN was found to be accumulated by protein analysis of WSN virus labeled biosynthetically with [35S]-methionine. It was strongly suggested that FUTHAN inhibited viral replication by preventing proteolytic cleavage of HA.

Morphological Changes of Escherichia coli Induced by Bicyclomycin

Electron microscopic studies with Escherichia coli revealed that bicyclomycin inhibits septum formation and converts the cells to filamentous forms. The antibiotic induced high undulation and numerous blebs of the outer membrane. Sometimes cytoplasmic contents leaked into the lumen of the bleb through a disrupted region of the membrane. Breakage of the outer membrane or blebs led to cell lysis. Electron-dense masses of amorphous material and vesicles were found in the cytoplasm. Images

Heavy meromyosin- and ATP-binding protein from Escherichia coli

Actin-like protein has been isolated from bacteria [l-5]. Elongation factor Tu from bacteria and actin from mammalian muscles have been compared [6]. EF-Tu polymerizes to form filaments and has certain actin-like properties; and may function as a structural protein of the envelope [2,3]. However, the 2 proteins show differences in the surface lattice structure and antigenicity [3]. Two major proteins from Escherichia coli have been isolated [4,5] whose properties are similar to those of skeletal actin. We have isolated 3 actin-like proteins, capable of binding to heavy meromyosin and ATP, from E. coli envelope fraction, using affinity chromatography; and demonstrated on gel electrophoresis that their molecular weights are different from E. coli EF-Tu and rabbit skeletal actin. The main protein is mol. wt -55 000. The results are presented here.