In Silico Analysis of Two Hard Tick P450s: Identification, Characterization, and Putative Metabolism of Cymbopogon citratus Essential Oil Constituents

The cytochrome p450 gene family is widely involved in various biological processes in arthropods. Tick p450s are often associated with chemical acaricides, but knowledge of their involvement in the metabolism of plant-derived essential oil components is limited. In this study, we identified the non-redundant number of p450 transcripts (NRNPTs) from <i>Haemaphysalis longicornis</i> and <i>Hyalomma asiaticum</i> under the <i>Cymbopogon citratus</i> essential oil (CCEO) and terpinolene stress using de novo transcriptome data, respectively. In this study, we identified and characterized the NRNPTs of <i>Ha. longicornis</i> and <i>Hy. asiaticum</i>. Their gene expression patterns and biological functions under CCEO and terpinolene stress were further analyzed. Finally, <i>Hy. asiaticum</i> NRNPTs (87) were more numerous than <i>Ha. longicornis</i> (58). Phylogenetic analyses showed that NRNPTs of both <i>Hy. asiaticum</i> and <i>Ha. longicornis</i> could be categorized in clan 2, clan 3, clan 4, and clan mito, this data comes from the NRNPTs. Phylogenetic analyses showed that NRNPTs of both <i>Hy. asiaticum</i> and <i>Ha. longicornis</i> could be categorized in clan 2, clan 3, clan 4, and clan mito. p450 members of both were most distributed in clan 3. In addition, one <i>Hy. asiaticum</i> NRNPT was identified as belonging to the new classification clan 20 (<i>Hyas</i>CYP20A1). The biological functions and pathways of p450 family members enriched in <i>Hy. asiaticum</i> and <i>Ha. longicornis</i> under different exogenous substance stresses were different, and the expression patterns of these genes were inconsistent. Molecular docking results showed that <i>Ha. longicornis</i> p450 members (<i>Halo</i>CYP3A4 and <i>Halo</i>CYP4B1), which were significantly up-regulated under CCEO stress, as well as <i>Hy. asiaticum Hyas</i>CYP24A1 and <i>Hyas</i>CYP4V2 (the <i>Halo</i>CYP3A4 and <i>Halo</i>CYP4B1 homologous genes), encode proteins that differ in their ability to metabolize CCEO components, but they all bind well to Germacrene D and naphthalene. Our study enriches the knowledge of the involvement of p450 family members of different tick species in the metabolism of essential oil components of plants, and provides a theoretical basis for further in-depth studies on the function of tick p450 enzymes.