Nakajima Y, van der Goes van Naters-Yasui A, Taylor D, Yamakawa M
Institute of Agriculture and Forestry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
Insect Biochem Mol Biol. 2001 Jun 22;31(8):747-51. doi: 10.1016/s0965-1748(01)00066-2.
We previously purified and determined the partial amino acid sequence of a 4 kDa peptide having high homology with scorpion defensin from the hemolymph 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 contains six cysteine residues conserved in the same location as other invertebrate defensins. Phylogenetic analysis reveals that Ornithodoros defensin is most closely related to scorpion defensin and other more ancient arthropods. Ornithodoros defensin mRNA is constitutively expressed and up-regulated by blood-feeding and bacterial injection. Ornithodoros defensin gene expression occurs mainly in the midgut. This is the first report of the cloning and gene expression of an antibacterial peptide from the Acari.
我们之前从成年雌性饱血软蜱钝缘蜱的血淋巴中纯化并测定了一种与蝎防御素具有高度同源性的4 kDa肽的部分氨基酸序列。在本研究中，获得了两种防御素亚型的全长序列。推导的氨基酸序列显示，前体蛋白有73个氨基酸残基，成熟部分由37个氨基酸残基组成。这种成熟肽含有六个半胱氨酸残基，其位置与其他无脊椎动物防御素相同且保守。系统发育分析表明，钝缘蜱防御素与蝎防御素及其他更古老的节肢动物关系最为密切。钝缘蜱防御素mRNA组成性表达，并在取食血液和注射细菌后上调。钝缘蜱防御素基因表达主要发生在中肠。这是关于蜱螨目抗菌肽克隆和基因表达的首次报道。
