A set of serine proteinase paralogs are required for blood-digestion in the ixodid tick Haemaphysalis longicornis.

Abstract

We present evidence demonstrating that genes encoding enzymes essential for successful blood-feeding are differentially induced in the midgut of the hard tick Haemaphysalis longicornis. Three serine proteinase genes (HlSP, HlSP2 and HlSP3) isolated from H. longicornis midgut exhibit protein sequence similarity with other trypsin-like serine proteinases reported from arthropods and vertebrate animal species. The endogenous enzymes were mainly detected in the midgut epithelial cells and in the lumen of an adult tick. The recombinant enzymes expressed in Escherichia coli efficiently hydrolyzed synthetic substrates specific for serine proteinases over a broad range of pH and temperature values. Notably, the transcript levels of HlSP2 and HlSP3 were detected to significantly increase at 96 h post infestation, while the transcript of HlSP was induced in the earlier stage of blood-feeding. Further, silencing of HlSP, HlSP2 and HlSP3 genes by RNA interference led to a significant reductions in the engorged tick body weight, suggesting synergetic roles of these serine proteinases in blood-feeding and digestion.

• Authors: Takeharu Miyoshi, Naotoshi Tsuji, M Khyrul Islam, M Abdul Alim, Takeshi Hatta, Xiaohong Huang, Kozo Fujisaki
• Journal: Parasitology international (Parasitol Int) Vol. 57 Issue 4 Pg. 499-505 (Dec 2008) ISSN: 1383-5769 [Print] Netherlands
• PMID: 18775510 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Recombinant Proteins
• HLSG-1 protein, Haemaphysalis longicornis
• HLSG-2 protein, Haemaphysalis longicornis
• Serine Endopeptidases

Topics

• Amino Acid Sequence
• Animals
• Blood (metabolism)
• Cloning, Molecular
• Digestive System (enzymology)
• Feeding Behavior
• Ixodidae (enzymology, genetics, physiology)
• Molecular Sequence Data
• RNA Interference
• Recombinant Proteins (genetics, metabolism)
• Sequence Analysis, DNA
• Sequence Homology, Amino Acid
• Serine Endopeptidases (chemistry, genetics, metabolism)