Structural and functional role of Domain I for the insecticidal activity of the <scp>Vip3Aa</scp> protein from <i>Bacillus thuringiensis</i>

Lázaro-Berenguer, Maria; Paredes-Martínez, Francisco; Bel, Yolanda; Núñez-Ramírez, Rafael; Arias-Palomo, Ernesto; Casino, Patricia; Ferré, Juan

doi:10.1111/1751-7915.14110

Cited by 14 publications

(10 citation statements)

References 56 publications

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“…It is noteworthy that, although Cry and Vip3 proteins have different primary sequences, the structural domains of Vip3 toxins resemble the first three domains reported for Cry toxins. Aside from the common shape-folded domains, it has been widely accepted that β-stranded domains of Vip3 and Cry toxins are involved in receptor binding ( 75 ), whereas the helical domains play a critical role in oligomerization and membrane insertion ( 76 ). The α-helical domain I of Vip3 is not present in Cry toxins, and Vip3 has two β-sandwich structural domains (domains IV and V) that share structural similarities with the β-sandwich domain III of Cry toxins.…”

Section: Structural Changes Of Vip3 Toxins During Pore Formationmentioning

confidence: 99%

Structural changes upon membrane insertion of the insecticidal pore-forming toxins produced by Bacillus thuringiensis

et al. 2023

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Different Bacillus thuringiensis (Bt) strains produce a broad variety of pore-forming toxins (PFTs) that show toxicity against insects and other invertebrates. Some of these insecticidal PFT proteins have been used successfully worldwide to control diverse insect crop pests. There are several studies focused on describing the mechanism of action of these toxins that have helped to improve their performance and to cope with the resistance evolved by different insects against some of these proteins. However, crucial information that is still missing is the structure of pores formed by some of these PFTs, such as the three-domain crystal (Cry) proteins, which are the most commercially used Bt toxins in the biological control of insect pests. In recent years, progress has been made on the identification of the structural changes that certain Bt insecticidal PFT proteins undergo upon membrane insertion. In this review, we describe the models that have been proposed for the membrane insertion of Cry toxins. We also review the recently published structures of the vegetative insecticidal proteins (Vips; e.g. Vip3) and the insecticidal toxin complex (Tc) in the membrane-inserted state. Although different Bt PFTs show different primary sequences, there are some similarities in the three-dimensional structures of Vips and Cry proteins. In addition, all PFTs described here must undergo major structural rearrangements to pass from a soluble form to a membrane-inserted state. It is proposed that, despite their structural differences, all PFTs undergo major structural rearrangements producing an extended α-helix, which plays a fundamental role in perforating their target membrane, resulting in the formation of the membrane pore required for their insecticidal activity.

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Section: Structural Changes Of Vip3 Toxins During Pore Formationmentioning

confidence: 99%

Structural changes upon membrane insertion of the insecticidal pore-forming toxins produced by Bacillus thuringiensis

et al. 2023

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“…Cryo-EM studies have revealed the tetrameric structure of Vip3Aa protoxin and trypsin-activated toxin, with each monomer being composed of five domains [ 14 ]. Domain I, containing four α-helices, plays a crucial role in both oligomerization and insecticidal activity [ 17 ]. This domain undergoes a conformational change during proteolytic activation, where helices α1 to α3 unfold and form a new N-terminal coiled-coil interacting with membranes [ 15 ].…”

Section: Discussionmentioning

confidence: 99%

“…Proteolytic digestion analysis also confirmed that domain I is a 19 kDa fragment of Vip3 toxins [ 11 ]. The crucial role of helix α1 in domain I has been shown for the insecticidal activity of the Vip3Aa toxin [ 17 ]. Domain II is composed of five α-helices, being the core of the tetramer that stabilizes the oligomeric structure [ 14 , 15 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

N-Terminal α-Helices in Domain I of Bacillus thuringiensis Vip3Aa Play Crucial Roles in Disruption of Liposomal Membrane

Shao,

Huang,

Yuan

et al. 2024

Toxins

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Bacillus thuringiensis Vip3 toxins form a tetrameric structure crucial for their insecticidal activity. Each Vip3Aa monomer comprises five domains. Interaction of the first four α-helices in domain I with the target cellular membrane was proposed to be a key step before pore formation. In this study, four N-terminal α-helix-deleted truncations of Vip3Aa were produced and, it was found that they lost both liposome permeability and insecticidal activity against Spodoptera litura. To further probe the role of domain I in membrane permeation, the full-length domain I and the fragments of N-terminal α-helix-truncated domain I were fused to green fluorescent protein (GFP), respectively. Only the fusion carrying the full-length domain I exhibited permeability against artificial liposomes. In addition, seven Vip3Aa-Cry1Ac fusions were also constructed by combination of α-helices from Vip3Aa domains I and II with the domains II and III of Cry1Ac. Five of the seven combinations were determined to show membrane permeability in artificial liposomes. However, none of the Vip3Aa-Cry1Ac combinations exhibited insecticidal activity due to the significant reduction in proteolytic stability. These results indicated that the N-terminal helix α1 in the Vip3Aa domain I is essential for both insecticidal activity and liposome permeability and that domain I of Vip3Aa preserved a high liposome permeability independently from domains II–V.

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“…In the insect midgut, tetrameric Vip3 protoxins are cleaved and activated by proteases such as trypsin. The activated toxins then bind potential receptors on the surfaces of the epithelial cells lining the midgut, form pores on the cell membranes, and cause cell death 10,17–20 . Studies on the functional mechanisms of Vip3 have facilitated its application in agriculture and advanced research on Sips 21–25 …”

Section: Introductionmentioning

confidence: 99%

“…The activated toxins then bind potential receptors on the surfaces of the epithelial cells lining the midgut, form pores on the cell membranes, and cause cell death. 10,[17][18][19][20] Studies on the functional mechanisms of Vip3 have facilitated its application in agriculture and advanced research on Sips. [21][22][23][24][25] Far less research has been conducted on Sips than on Cry and Vip3 toxins.…”

Section: Introductionmentioning

confidence: 99%

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

Chen,

Shi,

Wang

et al. 2023

Pest Management Science

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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.

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Structural and functional role of Domain I for the insecticidal activity of the Vip3Aa protein from Bacillus thuringiensis

Cited by 14 publications

References 56 publications

Structural changes upon membrane insertion of the insecticidal pore-forming toxins produced by Bacillus thuringiensis

Structural changes upon membrane insertion of the insecticidal pore-forming toxins produced by Bacillus thuringiensis

N-Terminal α-Helices in Domain I of Bacillus thuringiensis Vip3Aa Play Crucial Roles in Disruption of Liposomal Membrane

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

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