Biological Characteristics of the Cytochrome P 450 Family and the Mechanism of Terpinolene Metabolism in Hyalomma asiaticum (Acari: Ixodidae).

The CYP450 enzyme is a superfamily enzyme ubiquitously found in nearly all organisms, playing a vital role in the metabolism of both endogenous and exogenous compounds, and in biosynthesis. Unfortunately, an understanding of its classification, functions, expression characteristics, and other biological traits in Hyalomma asiaticum, a vector for Crimean-Congo Hemorrhagic Fever, as well as of the genes implicated in its natural product metabolism, is lacking. Towards this end, this study has identified 120 H. asiaticum CYP450 genes via transcriptome data in the face of a joint genome threat from terpinolene. The proteins these genes encode are of higher molecular weight, devoid of a signal peptide, and composed of unstable hydrophobic proteins principally containing 1-3 variable transmembrane regions. Phylogenetic evolution classifies these H. asiaticum CYP450 genes into four subfamilies. These genes all encompass complete CYP450 conserved domains, and five specific conserved motifs, albeit with different expression levels. GO and KEGG annotation findings suggest a widespread distribution of these CYP450 genes in many physiological systems, predominantly facilitating lipid metabolism, terpenoid compound metabolism, and polyketone compound metabolism, as well as cofactor and vitamin metabolism at a cellular level. Molecular docking results reveal a hydrophobic interaction between the ARG-103, ARG-104, LEU-106, PHE-109, and ILE-119 amino acid residues in CYP3A8, which is primarily expressed in the fat body, and terpinolene, with a notably up-regulated expression, with affinity = -5.6 kcal/mol. The conservation of these five key amino acid residues varies across 12 tick species, implying differences in terpinolene metabolism efficacy among various tick species. This study thereby fills an existing knowledge gap regarding the biological characteristics of H. asiaticum CYP450 genes and paves the way for further research into the functions of these particular genes.