Scavenger receptor-C acts as a receptor for Bacillus thuringiensis vegetative insecticidal protein Vip3Aa and mediates the internalization of Vip3Aa via endocytosis

Vip3A proteins are widely used for controlling pest Lepidoptera. Different binding sites with different receptors in the insect midgut membrane and lack of cross‐resistance with crystal (Cry) proteins enhance their applicability, as both single proteins and proteins pyramided with Cry proteins in transgenic Bt crops. Vip3A proteins are effective but there is relatively little information about their structure, function, activation, specificity, and mode of action. In addition, the mechanism of insect resistance to these proteins is unknown. Phylogenetic analysis and multiple sequence alignment showed that Vip3A proteins are genetically distant from Cry proteins. The mode of action and insecticidal activity of Vip3A proteins are discussed in this review. This review also provides detailed information about the Vip3A protein family that may aid in the design of more efficient pest management strategies in response to insect resistance to insecticidal proteins. © 2020 Society of Chemical Industry

Section: Mode Of Action Of Vip3a Proteinsmentioning

confidence: 99%

Section: Resistance and Cross Resistancementioning

confidence: 99%

Section: Future Research Needsmentioning

confidence: 99%

Section: Wileyonlinelibrarycom/journal/psmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bacillus thuringiensis vegetative insecticidal protein family Vip3A and mode of action against pest Lepidoptera

Chakrabarty

Jin

et al. 2020

RNA interference of PHB1 enhances virulence of Vip3Aa to Sf9 cells and Spodoptera frugiperda larvae

Zhang

Yan

et al. 2023

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BACKGROUND In our previous work, we demonstrated that prohibitin 2 (PHB2) on the membrane of Sf9 cells was a receptor for Vip3Aa, and PHB2 in mitochondria contributed to the mitochondrial stability to reduce Vip3Aa toxicity. Prohibitin 1 (PHB1), another prohibitin family member, forms heterodimers with PHB2 to maintain the structure and stability of mitochondria. To explore whether PHB1 impacts the action process of Vip3Aa, we examined the correlation between PHB1 and Vip3Aa virulence. RESULTS We revealed that PHB1 did not colocalize with Vip3Aa in Sf9 cells. The pulldown and CoIP experiments confirmed that PHB1 interacted with neither Vip3Aa nor scavenger receptor‐C (another Vip3Aa receptor). Downregulating phb1 expression in Sf9 cells did not affect the internalization of Vip3Aa but increased Vip3Aa toxicity. Further exploration revealed that the decrease of phb1 expression affected mitochondrial function, leading to increased ROS levels and mitochondrial membrane permeability and decreased mitochondrial membrane potential. The increase of mitochondrial cytochrome c release, caspase‐3 activity and genomic DNA fragmentation implied that the apoptotic process was also affected. Finally, we applied RNAi to inhibit phb1 expression in Spodoptera frugiperda larvae. As a result, it significantly increased Vip3Aa virulence. CONCLUSION We found that PHB1 was not a receptor for Vip3Aa but played an essential role in mitochondria. The downregulation of phb1 expression in Sf9 cells caused instability of mitochondria, and the cells were more prone to apoptosis when challenged with Vip3Aa. The combined use of Vip3Aa and phb1 RNAi showed a synergistic effect against S. frugiperda larvae. © 2023 Society of Chemical Industry.

Structural insight into Bacillus thuringiensis Sip1Ab reveals its similarity to ETX_MTX2 family beta‐pore‐forming toxin

Chen,

Shi,

Wang

et al. 2023

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BACKGROUNDMicrobially derived, protein‐based biopesticides are an important approach for sustainable pest management. The secreted insecticidal proteins (Sips) produced by the bacterium Bacillus thuringiensis exhibit potent insecticidal activity against coleopteran pests and are, therefore, attractive as candidate biopesticides. However, the modes‐of‐action of Sips are unclear as comprehensive structural information for these proteins is lacking.RESULTSUsing X‐ray crystallography, we elucidated the structure of monomeric Sip1Ab at 2.28 Å resolution. Structural analyses revealed that Sip1Ab has the three domains and conserved fold characteristic of other aerolysin‐like beta‐pore‐forming toxins (β‐PFTs). Based on the sequence and structural similarities between Sip1Ab and other ETX_MTX2 subfamily toxins, we suggested the mechanism of these proteins and proposed that it is common to them all.CONCLUSIONThe atomic‐level structural data for Sip1Ab generated by the present study could facilitate future structural and mechanistic research on Sips as well as their application in sustainable insect pest management. © 2023 Society of Chemical Industry.