Identification and characterization of antimicrobial peptide, defensin, in the taiga tick, ixodes persulcatus

Y. Saito, S. Konnai, S. Yamada, S. Imamura, H. Nishikado, T. Ito, M. Onuma, K. Ohashi

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Ixodes persulcatus is the primary vector for human tick-borne diseases in Japan. A cDNA library was constructed from whole body homogenates of fed nymphs of I. persulcatus. From this library, one cDNA encoding defensin-like antimicrobial peptide was identified. The amino-acid sequence showed high similarity to those of the defensins of other ticks and arthropods. I. persulcatus defensin mRNA transcripts were detected at all life cycle stages of fed ticks and found to be predominantly expressed in the midguts of adult female ticks, but not in the salivary glands, a finding corroborated by Western blotting analysis. To investigate the function of I. persulcatus defensin, we examined its antibacterial activity by evaluation of growth of several bacterial strains in the presence of the synthetic peptide. The defensin from I. persulcatus markedly inhibited the growth of Gram-positive bacteria including Staphylococcus aureus, Bacillus subtilis and Corynebacterium renale, but not Gram-negative bacteria except Escherichia coli O157. In conclusion, these results suggest that I. persulcatus defensin may be playing a significant role in the defence against microbes from bloodmeals.

Original languageEnglish
Pages (from-to)531-539
Number of pages9
JournalInsect Molecular Biology
Volume18
Issue number4
DOIs
Publication statusPublished - 2009 Aug

Keywords

  • Antimicrobial peptide
  • CDNA library
  • Defensin
  • Ixodes persulcatus

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Insect Science

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