Potentiation and cellular phenotypes of the insecticidal Toxin complexes of Photorhabdus bacteria

Waterfield, Nicholas R.; Hares, Michelle C.; Yang, Guowei; Dowling, Andrea J.; ffrench‐Constant, Richard H.

doi:10.1111/j.1462-5822.2004.00467.x

Cited by 86 publications

(99 citation statements)

References 18 publications

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“…In addition to these three insecticidal toxins, the P. entomophila genome, like that of P. syringae, encodes proteins more distantly related to TccC-type toxins (PSEEN701 and PSEEN702) and to TcdB-type toxins (PSEEN1172). The three P. entomophila insecticidal toxins likely play a major role in the pathogenicity of P. entomophila as TccC and TcdB proteins have been shown to have entomocidal activity 15,16 , even though the molecular mechanisms remain to be characterized. These findings highlight the efficient spreading of toxin-complex gene homologs in insect-interacting soil bacteria belonging to different genera.…”

Section: Toxins Against Insectsmentioning

confidence: 99%

Complete genome sequence of the entomopathogenic and metabolically versatile soil bacterium Pseudomonas entomophila

et al. 2006

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Pseudomonas entomophila is an entomopathogenic bacterium that, upon ingestion, kills Drosophila melanogaster as well as insects from different orders. The complete sequence of the 5.9-Mb genome was determined and compared to the sequenced genomes of four Pseudomonas species. P. entomophila possesses most of the catabolic genes of the closely related strain P. putida KT2440, revealing its metabolically versatile properties and its soil lifestyle. Several features that probably contribute to its entomopathogenic properties were disclosed. Unexpectedly for an animal pathogen, P. entomophila is devoid of a type III secretion system and associated toxins but rather relies on a number of potential virulence factors such as insecticidal toxins, proteases, putative hemolysins, hydrogen cyanide and novel secondary metabolites to infect and kill insects. Genome-wide random mutagenesis revealed the major role of the two-component system GacS/GacA that regulates most of the potential virulence factors identified.

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Section: Toxins Against Insectsmentioning

confidence: 99%

Complete genome sequence of the entomopathogenic and metabolically versatile soil bacterium Pseudomonas entomophila

et al. 2006

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“…In some cases, expression of individual tcA genes is sufficient to cause toxicity (8,11), but full toxicity generally requires all three Tc components, with the B and C components providing a potentiation of toxicity (12,13). Interestingly, TcB and TcC components coexpressed with TcA components from other species (or from other Tc clusters) can combine to cause an effect with altered host specificity (12,13), suggesting the TcA component is a determinant of target host range. Further evidence for this is provided by the observation that the TcA components of an insecticidal X. nematophila Tc bind to solubilized insect midgut brush border membranes (14,15).…”

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3D structure of the Yersinia entomophaga toxin complex and implications for insecticidal activity

Landsberg

Jones

Rothnagel

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Toxin complex (Tc) proteins are a class of bacterial protein toxins that form large, multisubunit complexes. Comprising TcA, B, and C components, they are of great interest because many exhibit potent insecticidal activity. Here we report the structure of a novel Tc, Yen-Tc, isolated from the bacterium Yersinia entomophaga MH96, which differs from the majority of bacterially derived Tcs in that it exhibits oral activity toward a broad range of insect pests, including the diamondback moth ( Plutella xylostella ). We have determined the structure of the Yen-Tc using single particle electron microscopy and studied its mechanism of toxicity by comparative analyses of two variants of the complex exhibiting different toxicity profiles. We show that the A subunits form the basis of a fivefold symmetric assembly that differs substantially in structure and subunit arrangement from its most well characterized homologue, the Xenorhabdus nematophila toxin XptA1. Histopathological and quantitative dose response analyses identify the B and C subunits, which map to a single, surface-accessible region of the structure, as the sole determinants of toxicity. Finally, we show that the assembled Yen-Tc has endochitinase activity and attribute this to putative chitinase subunits that decorate the surface of the TcA scaffold, an observation that may explain the oral toxicity associated with the complex.

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“…These complexes comprise at least three proteins (A, B and C), which must assemble to be fully toxic 4 . The carboxy-terminal region of C is the main cytotoxic component 5 , and is poorly conserved between different Tcs.…”

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The BC component of ABC toxins is an RHS-repeat-containing protein encapsulation device

Busby

Panjikar

Landsberg

et al. 2013

Nature

136

198

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The ABC toxin complexes (Tc) produced by certain bacteria are of interest due to their potent insecticidal activity 1,2 and potential role in human disease 3 . These complexes comprise at least three proteins (A, B and C), which must assemble to be fully toxic 4 . The carboxy-terminal region of C is the main cytotoxic component 5 , and is poorly conserved between different Tcs. A general model of action has been proposed, in which the Tc binds to the cell surface via the A protein, is endocytosed, and subsequently forms a pH-triggered channel, allowing the translocation of C into the cytoplasm, where it can cause cytoskeletal disruption in both insect and mammalian cells 5 . Tc complexes have been visualised using single particle electron microscopy 6,7 , but no high-resolution structures of the components are available, and the role of the B protein in the mechanism of toxicity remains unknown. Here we report the three-dimensional structure of the complex formed between the B and C proteins, determined to 2.5 Å by X-ray crystallography. These proteins assemble to form an unprecedented, large hollow structure that encapsulates and sequesters the cytotoxic, carboxy-terminal region of the C protein like the shell of an egg. The shell is decorated on one end with a -propeller domain, which mediates attachment of the B/C heterodimer to the A protein in the native complex. The structure reveals how C auto-proteolyses when folded in complex with B. The C protein is the first example of a structure that contains RHS (rearrangement hot spot) repeats 8 , and illustrates a striking structural architecture that is likely conserved across both this widely distributed bacterial protein family and the related eukaryotic YD-repeatcontaining protein family, which includes the teneurins 9 . The structure provides the first clues about the function of these protein repeat families, and suggests a generic mechanism for protein encapsulation and delivery.ABC toxins were first identified, and have been best characterised, in the bacterium Photorhabdus luminescens 1 . However, the entomopathogenic bacterium Yersinia entomophaga contains a related Tc locus that includes an A component encoded by two ORFs (yenA1 and yenA2), a single B gene (yenB) and two C genes (yenC1 and yenC2), 10 the products of which associate independently with the A and B proteins, giving rise to two Tcs from one genetic locus. The C proteins of this and other Tcs are similar to the "polymorphic toxins" described by Zhang et al. 11 as they have a conserved RHS-repeat-containing amino-terminal region and a variable carboxyterminal region 10 . The carboxy-terminal regions (CTRs) of the Y. entomophaga C proteins are predicted to have different toxic activities: the C1 CTR is homologous to cytotoxic necrotising factor 1 (CNF1) from Escherichia coli 12 , whereas the C2 CTR is homologous to the deaminase YwqJ from Bacillus subtilis 13 . As in related complexes 3 , when the B subunit is co-expressed with either of the C subunits, C is cleaved at the boundary between th...

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Potentiation and cellular phenotypes of the insecticidal Toxin complexes of Photorhabdus bacteria

Cited by 86 publications

References 18 publications

Complete genome sequence of the entomopathogenic and metabolically versatile soil bacterium Pseudomonas entomophila

Complete genome sequence of the entomopathogenic and metabolically versatile soil bacterium Pseudomonas entomophila

3D structure of the Yersinia entomophaga toxin complex and implications for insecticidal activity

The BC component of ABC toxins is an RHS-repeat-containing protein encapsulation device

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