关键词: 长须血蜱, 嗅觉, C型尼曼-匹克蛋白2, 气味结合蛋白样蛋白, Microplusin样蛋白

Abstract: Objective To investigate the molecular basis and mechanism of olfaction of ticks, and to identify the molecular structure of olfaction-related proteins of Haemaphysalis aponommoides and predict their function features.Methods The transcripts of olfaction-related proteins of Ha. aponommoides were acquired through transcriptome sequencing. The secondary and tertiary structures of these proteins were predicted with the use of ESPript 3.0 and Swiss-Model softwares. Based on molecular modeling, the structure features and protein-ligand interaction features of the olfaction-related proteins of Ha. aponommoides were explored.Results A total of 6 olfaction-related transcripts of Ha. aponommoides were acquired, and the corresponding protein sequences were highly homologous to Niemann-Pick C2 (NPC2), odorantbinding protein-like protein (OBPL), and microplusin-like protein in Ha. longicornis and Dermacentor silvarum. The OBPL domain consisted of 5 α-helices and 41.83% hydrophobic residues, forming a ligand-binding pocket, and in the NPC2 domain, 5 turns and 9 β-sheets comprised a ligand-binding pocket. The ligands of volatile odors were shown overlapped in the center of the pockets with their ligands.Conclusion The OBPL and NPC2 of Ha. longicornis possess a structure enabling odor sensation, suggesting their involvement in olfactory function in ticks.

Key words: Haemaphysalis aponommoides, Olfaction, Niemann-Pick C2 protein, Odorant binding protein-like, Microplusin-like protein