Structural modeling and expression analysis of Aedes aegypti prophenoloxidase 5 (PPO5) gene

Abstract

Aedes aegypti mosquitoes, the major intermediate host of infectious arthropod-borne viral diseases, possess prephenoloxidases (PPOs), enzymes involved in melanization, are crucial for mosquito immunity and development. RNA-seq analyses of PPO5 gene revealed stage-specific and sex-biased expressions, with notably higher levels in female pupae and adults. This gene showed significant upregulation in ovaries 12-24 h post-blood feeding, suggesting its involvement in blood meal-associated physiological changes. Physicochemical analysis indicated that PPO5 is hydrophilic, with a slightly acidic pI and exhibits moderate thermostability. Secondary-structure analyses of PPO5 protein revealed the dominance of alpha-helices and random coils, while homology modeling suggested a homodimeric structure with conserved copper-binding catalytic region. Functional characterization revealed that PPO5 is a secreted protein without any signal peptide and likely involved in immunity and development. The present research improves our understanding of PPO5 molecular features and highlights its possiblities as a target for novel mosquito vector control strategies.