title: Isolation and characterization of two novel serpins from the tick Rhipicephalus haemaphysaloides.
abstract: Two novel serpins with anti-chymotrypsin activity, RHS-1 and RHS-2, were identified in the tick Rhipicephalus haemaphysaloides. The complementary cDNA sequence of RHS-1 was 1286 base pairs (bp) and encoded a deduced 403-amino acid protein with a signal peptide, whereas that of RHS-2 was 1682bp and encoded a deduced 380-amino acid protein with no signal peptide. Although both RHS-1 and RHS-2 exhibited high sequence similarities to known serpins from other ticks, the level of similarity at the amino acid level between the 2 serpins characterized here was only 32.5%. Salivary gland-specific expression of RHS-1 and midgut-specific expression of RHS-2 were found by Western blot using the relevant antiserum. We tested the ability of purified recombinant rRHS-1 and rRHS-2 to inhibit various serine proteases and found that both significantly inhibited chymotrypsin (95.6% and 94.2%, respectively). We further demonstrated that RHS-1, but not RHS-2 exhibited anticoagulation activity, based on activated partial thromboplastin time (APTT). Disruption of the genes encoding the 2 serpins with RNA interference (RNAi) led to a significant decrease in tick attachment and engorgement rates. These results indicate that RHS-1 and RHS-2 are 2 novel serpins with anti-chymotrypsin activity that are involved in blood feeding of R. haemaphysaloides.
authors.affiliation: Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China.
authors.forename: Yingfang
authors.initials: Y
authors.lastname: Yu
authors.forename: Jie
authors.initials: J
authors.lastname: Cao
authors.forename: Yongzhi
authors.initials: Y
authors.lastname: Zhou
authors.forename: Houshuang
authors.initials: H
authors.lastname: Zhang
authors.forename: Jinlin
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D034622:RNA Interference; D048494:Rhipicephalus / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015843:Serpins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; D015843:Serpins