Y. Nakajima et al., Two isoforms of a member of the arthropod defensin family from the soft tick, Ornithodoros moubata (Acari : Argasidae), INSEC BIO M, 31(8), 2001, pp. 747-751
We previously purified and determined the partial amino acid sequence of a
4 kDa peptide having high homology with scorpion defensin from the hemolymp
h of adult fed female soft ticks, Ornithodoros moubata. In this study, the
full length sequences of two defensin isoforms were obtained. Deduced amino
acid sequences reveal a precursor protein of 73 amino acid residues with a
mature portion consisting of 37 amino acid residues. This mature peptide c
ontains six cysteine residues conserved in the same location as other inver
tebrate defensins. Phylogenetic analysis reveals that Ornithodoros defensin
is most closely related to scorpion defensin and other more ancient arthro
pods. Ornithodoros defensin mRNA is constitutively expressed and up-regulat
ed by blood-feeding and bacterial injection. Ornithodoros defensin gene exp
ression occurs mainly in the midgut. This is the first report of the clonin
g and gene expression of an antibacterial peptide from the Acari. (C) 2001
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