Evolution of the Insect PPK Gene Family

LATORRE-ESTIVALIS, JOSE MANUEL; ALMEIDA, FRANCISCA C; PONTES, GINA; DOPAZO, HERNÁN; BARROZO, ROMINA B; LORENZO, MARCELO GUSTAVO

Genome Biology and Evolution

Oxford Academic

Año: 2021 vol. 13

Insect pickpocket (PPK) receptors mediate diverse functions, among them the detection of mechano- and chemo-sensory stimuli.Notwithstanding their relevance, studiesontheir evolutiononly focusedonDrosophila.Wehave analyzedthegenomes of26speciesof eight orders including holometabolous and hemimetabolous insects (Blattodea, Orthoptera, Hemiptera, Phthiraptera,Hymenoptera, Lepidoptera, Coleoptera, and Diptera), to characterize the evolution of this gene family. PPKs were detected in allgenomes analyzed, with 578 genes distributed in seven subfamilies. According to our phylogeny, ppk17 is the most divergentmember, composing the new subfamily VII. PPKs evolved under a gene birth-and-death model that generated lineage-specificexpansions usually located in clusters,whilepurifying selection affected several orthogroups. SubfamilyVwas the largest, including amosquito-specific expansion that can be considered a new target for pest control. PPKs present a high gene turnover generatingconsiderable variation. On one hand, Musca domestica (59), Aedes albopictus (51), Culex quinquefasciatus (48), and Blattellagermanica (41) presented the largest PPK repertoires. On the other hand, Pediculus humanus (only ppk17), bees, and ants (6?9)hadthesmallest PPKsets.Asubset of prevalent PPKswas identified, indicatingvery conservedfunctions for these receptors. Finally, atleast 20% of the sequences presented calmodulin-binding motifs, suggesting that these PPKs may amplify sensory responsessimilarly as proposed forDrosophilamelanogaster ppk25.Overall, thiswork characterized the evolutionary history of these receptorsrevealing relevant unknown gene sequence features and clade-specific expansions.