Hidenori Iwahana

Publications (2)5.11 Total impact

• Article: Multipeptide precursor structure of acaloleptin A isoforms, antibacterial peptides from the Udo longicorn beetle, Acalolepta luxuriosa.

  Morikazu Imamura, Sugino Wada, Kenjiro Ueda, Ayaka Saito, Nobuo Koizumi, Hidenori Iwahana, Ryoichi Sato
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  ABSTRACT: We previously purified acaloleptin A1, A2, and A3, antibacterial peptides that are produced in the larval hemolymph of Acalolepta luxuriosa (Udo longicorn beetle). In this study, we performed cDNA cloning. The cDNA sequence showed a predicted acaloleptin A precursor that consisted of five acaloleptin A isoforms. Four (isoforms 1, 2, 3 and 4) of the five isoforms of the acaloleptin A precursor had high-level sequence identities with each other, but the N-terminal region of isoform 5 differed from those of the other acaloleptin A isoforms. Northern and Western blot analyses showed that acaloleptin A isoforms were mass-produced soon after bacterial inoculation. Finally, we purified isoform 5 from hemolymph of the immunized larvae. Isoform 5, unlike acaloleptin A1, A2 and A3, showed antimicrobial activities against a Gram-positive bacterium, Micrococcus luteus and a fungus, Magnaporthe grisea. These results suggest that the multipeptide structure of the acaloleptin A precursor allows A. luxuriosa high-level production of antibacterial peptides and resistance to a wide range of microorganisms.
  Developmental and comparative immunology 07/2009; 33(10):1120-7. · 3.29 Impact Factor
• Article: Binding of Phylogenetically Distant Bacillus thuringiensis Cry Toxins to a Bombyx mori Aminopeptidase N Suggests Importance of Cry Toxin's Conserved Structure in Receptor Binding

  Ayaka Shinkawa, Katsuro Yaoi, Tomoyuki Kadotani, Morikazu Imamura, Nobuo Koizumi, Hidenori Iwahana, Ryoichi Sato
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  ABSTRACT: We investigated the binding proteins for three Cry toxins, Cry1Aa, Cry1Ac, and the phylogenetically distant Cry9Da, in the midgut cell membrane of the silkworm. In a ligand blot experiment, Cry1Ac and Cry9Da bound to the same 120-kDa aminopeptidase N (APN) as Cry1Aa. A competition experiment with the ligand blot indicated that the three toxins share the same binding site on several proteins. The values of the dissociation constants of the three Cry toxins and 120-kDa APN are as low as the case of other Cry toxins and receptors. These results suggest that distantly related Cry toxins bind to the same site on the same proteins, especially with APN. We propose that the conserved structure in these three toxins includes the receptor-binding site.
  Current Microbiology 01/1999; 39(1):14-20. · 1.82 Impact Factor