Pacheco Sabino, Chiñas Marcos, Gómez Juan Ulises, Peláez-Aguilar Ángel Enrique, do Nascimento Nathaly Alexandre, Cantón Pablo Emiliano, Sánchez Jorge, López-Molina Samira, Gómez Isabel, Soberón Mario, Bravo Alejandra
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico.
PLoS One. 2025 Jul 3;20(7):e0327221. doi: 10.1371/journal.pone.0327221. eCollection 2025.
ABC transporters are membrane proteins that modulate the insecticidal activity of Bacillus thuringiensis Cry toxins by acting as receptors in the gut epithelium of insect larvae. However, their role as Cry receptors in dipteran species remains unknown. Here, we identified the ABC transporter orthologs in the Aedes aegypti genome corresponding to the Cry toxin receptors described in lepidopteran and coleopteran species. Analysis of their transcriptomic regulation in gut tissue, revealed the expression of ABCA2, ABCB1, and ABCC2. Using CRISPR-Cas9, we knocked out (KO) the expression of these three ABC transporter genes and performed in vivo binding assays and bioassays with four mosquitocidal Cry toxins (Cry4Aa, Cry4Ba, Cry11Aa, and Cry11Ba). Histopathological analysis showed a significant reduction of Cry toxins binding to the apical microvilli membrane of gut epithelium, depending on the ABC KO mutation. However, similar larvicidal activity was observed for Cry toxins between ABC KO and wild type strains. Transcriptomic analysis revealed specific upregulation of their corresponding ABC transporter paralogous, suggesting a compensatory mechanism that could mitigate the fitness cost of the ABC KO and potentially contribute to redundant receptor function of Cry toxins. These findings provide evidence that ABC transporters may act as physiological receptors for insecticidal Cry toxins in dipteran insects.
ABC转运蛋白是膜蛋白，通过在昆虫幼虫肠道上皮中作为受体来调节苏云金芽孢杆菌Cry毒素的杀虫活性。然而，它们在双翅目物种中作为Cry受体的作用仍不清楚。在这里，我们在埃及伊蚊基因组中鉴定出了与鳞翅目和鞘翅目物种中描述的Cry毒素受体相对应的ABC转运蛋白直系同源物。对它们在肠道组织中的转录调控分析揭示了ABCA2、ABCB1和ABCC2的表达。利用CRISPR-Cas9，我们敲除了这三个ABC转运蛋白基因的表达，并对四种杀蚊Cry毒素（Cry4Aa、Cry4Ba、Cry11Aa和Cry11Ba）进行了体内结合试验和生物测定。组织病理学分析表明，根据ABC基因敲除突变情况，Cry毒素与肠道上皮顶端微绒毛膜的结合显著减少。然而，在ABC基因敲除菌株和野生型菌株之间观察到Cry毒素具有相似的杀幼虫活性。转录组分析揭示了其相应的ABC转运蛋白旁系同源物的特异性上调，表明存在一种补偿机制，可以减轻ABC基因敲除的适应性成本，并可能有助于Cry毒素的冗余受体功能。这些发现提供了证据，表明ABC转运蛋白可能在双翅目昆虫中作为杀虫Cry毒素的生理受体。
