The PhlA Hemolysin from the Entomopathogenic Bacterium
            <i>Photorhabdus</i>
            <i>luminescens</i>
            Belongs to the Two-Partner Secretion Family of Hemolysins

Brillard, Julien; Duchaud, Éric; Boemare, Noël; Kunst, Frank; Givaudan, Alain

doi:10.1128/jb.184.14.3871-3878.2002

Cited by 79 publications

(85 citation statements)

References 51 publications

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“…Several of these toxins are on the ends of contigs, however, and may still be intact. A gene encoding the putative hemolysin toxin (PhlA), belonging to a two-partner secretion system was identified; however, a gene encoding the secretion protein PhlB, required for exotoxin secretion into the extracellular environment (Brillard et al 2002), was not detectable. Also, R. insecticola 5.15 encoded three truncated toxins belonging to the clostridial glycosylating toxin family and a truncated calmodulin-sensitive adenylate cyclase toxin.…”

Section: Exotoxins and Type I Secretion Systems ( T1ss)mentioning

confidence: 99%

Genomic basis of endosymbiont-conferred protection against an insect parasitoid

Hansen¹,

Vorburger²,

Moran³

2011

Genome Res.

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Bacterial endosymbionts exert a variety of beneficial effects on insect hosts. In pea aphids (Acyrthosiphon pisum), several inherited endosymbiont species protect their hosts against parasitoid wasps, which are major natural enemies. However, strains of these symbiont species vary in their ability to confer protection against parasitoids, with some conferring almost complete protection and others conferring almost none. In this study, two strains of the endosymbiont Regiella insecticola (R. insecticola 5.15 and R. insecticola LSR1) were found to differ in ability to protect pea aphids attacked by the parasitoid Aphidius ervi. Parasitism trials reveal that R. insecticola 5.15, but not R. insecticola LSR1, significantly reduced parasitoid success and increased aphid survivorship. To address the potential genetic basis of protection conferred by R. insecticola 5.15 we sequenced the genome of this symbiont strain, and then compared its gene repertoire with that of the already sequenced nonprotective strain R. insecticola LSR1. We identified striking differences in gene sets related to eukaryote pathogenicity. The protective strain R. insecticola 5.15 encoded five categories of pathogenicity factors that were missing or inactivated in R. insecticola LSR1. These included genes encoding the O-antigen biosynthetic pathway, an intact Type 1 Secretion System and its secreted RTX toxins, an intact SPI-1 Type 3 Secretion System and its effectors, hemin transport, and the twocomponent system PhoPQ. These five pathogenicity factors and translocation systems are hypothesized to collectively play key roles in the endosymbiont's virulence against parasitoids, resulting in aphid protection. Mechanisms through which these factors may target parasitoids are discussed.

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Section: Exotoxins and Type I Secretion Systems ( T1ss)mentioning

confidence: 99%

Genomic basis of endosymbiont-conferred protection against an insect parasitoid

Hansen¹,

Vorburger²,

Moran³

2011

Genome Res.

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“…luminescens contains eight genes predicted to encode hemolysinor hemagglutinin-related proteins secreted by the two-partner secretion (TPS) pathway. These comprise the secreted PhlA protein and the PhlB protein, which allows secretion and activation of PhlA 13 . We identified six other TPS gene pairs and ten incomplete loci (Supplementary Table 3 online).…”

Section: A R T I C L E Smentioning

confidence: 99%

The genome sequence of the entomopathogenic bacterium Photorhabdus luminescens

et al. 2003

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Photorhabdus luminescens is an enterobacterium that is symbiotic with soil entomopathogenic nematodes and pathogenic to a wide range of insects. P. luminescens promotes its own transmission among susceptible insect populations using its nematode host as vector 1 . Its life cycle comprises a symbiotic stage in the nematode's gut and a virulent stage in the insect larvae, which it kills through toxemia and septicemia. After the nematode attacks a prey insect and P. luminescens is released, the bacterium produces a wide variety of virulence factors ensuring rapid insect killing. Bioconversion of the insect cadaver by exoenzymes produced by the bacteria allows the bacteria to multiply and the nematode to reproduce. During this process P. luminescens produces antibiotics to prevent invasion of the insect cadaver by bacterial or fungal competitors. Finally, elimination of competitors allows P. luminescens and the nematode to reassociate specifically before leaving the insect cadaver 2,3 .To better understand this complex life style, we determined the genome sequence of P. luminescens subspecies laumondii strain TT01 4 , a symbiont of the nematode Heterorhabditis bacteriophora isolated on Trinidad and Tobago. RESULTS General featuresStrain TT01 possesses a single circular chromosome of 5,688,987 bp with an average GC content of 42.8%. No plasmid replicon was found.A total of 4,839 protein-coding genes, including 157 pseudogenes, seven complete sets (23S, 5S and 16S) of ribosomal RNA operons and 85 tRNA genes, were predicted ( Fig. 1; Supplementary Table 1 online). Toxins against insectsMore toxin genes were predicted in the P. luminescens genome than in any other bacterial genome sequenced yet. A large number of these toxins may be involved in the killing of a wide variety of insects. Some may act synergistically or use redundancy for 'overkill' 5 , ensuring a quick death of the host. In addition, some may kill insects by interfering with their development. In the TT01 genome, two paralogs, plu4092 and plu4436, encode proteins similar to juvenile hormone esterases (JHEs) of the insect Leptinotarsa decemlineata 6 . Juvenile hormone maintains the insect in a larval state. Its inactivation by JHE allows metamorphosis to proceed. JHEs may be used to trigger the insect endocrine machinery at an inappropriate time and thus represents a promising approach for insect control 7 . These genes are located downstream of highly related orphan genes (plu4093 and plu4437), suggesting a locus duplication.The toxicity of the proteins encoded by these two loci was verified experimentally. Two Escherichia coli clones, containing the recombinant BAC1A02 and BAC8C11, were shown to be toxic toward insects. BAC1A02, which contains the locus plu4093-plu4092, exhibited substantial oral toxicity toward three mosquito species, Aedes aegypti,

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“…There is also limited information available about the Xin toxin, which has a molecular mass of greater than 1000 kDa, is expressed intercellularly, and is orally toxic to H. armigera larvae (21). The PhlA hemolysin was shown not to be a major virulence determinant (22). The Tc toxins from P. luminescens W14 form a large protein complex that is toxic to insects by either ingestion or injection (17)(18)(19).…”

Section: Discussionmentioning

confidence: 99%

“…Other toxin proteins isolated and characterized from bacteria related to Xenorhabdus are the Tc toxins from P. luminescens strain W14 (17)(18)(19), a 39-kDa toxin from X. nematophila (20), the large Xin toxin from X. nematophila strain BJ (21), and the PhlA hemolysin from P. luminescens strain TT01 (22). Of these, only the Tc toxins have been studied in any detail.…”

Section: Discussionmentioning

confidence: 99%

“…Analysis of the genome of P. luminescens identified more predicted toxin genes than any other bacteria sequenced to date, including potential gene products with homology to hemolysin A, chitinase, Rtx (repeats-in-toxin)-like toxin, and ␦-endotoxin (5). The only toxins studied in detail are the Tc toxins from P. luminescens strain W14 (17)(18)(19), although a small amount of work has also been done on a 39-kDa toxin from X. nematophila (20), the large Xin toxin from X. nematophila strain BJ (21), and the PhlA hemolysin from P. luminescens strain TT01 (22). This paper describes the identification, purification, and characterization of a novel insect toxin from X. nematophila strain A24.…”

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confidence: 99%

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A Novel Secreted Protein Toxin from the Insect Pathogenic Bacterium Xenorhabdus nematophila

Brown

Cao

Hines

et al. 2004

Journal of Biological Chemistry

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The bacterium Xenorhabdus nematophila is an insect pathogen that produces several proteins that enable it to kill insects. Screening of a cosmid library constructed from X. nematophila strain A24 identified a gene that encoded a novel protein that was toxic to insects. The 42-kDa protein encoded by the toxin gene was expressed and purified from a recombinant system, and was shown to kill the larvae of insects such as Galleria mellonella and Helicoverpa armigera when injected at doses of around 30 -40 ng/g larvae. Sequencing and bioinformatic analysis suggested that the toxin was a novel protein, and that it was likely to be part of a genomic island involved in pathogenicity. When the native bacteria were grown under laboratory conditions, a soluble form of the 42-kDa toxin was secreted only by bacteria in the phase II state. Preliminary histological analysis of larvae injected with recombinant protein suggested that the toxin primarily acted on the midgut of the insect. Finally, some of the common strategies used by the bacterial pathogens of insects, animals, and plants are discussed.

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The PhlA Hemolysin from the Entomopathogenic Bacterium Photorhabdus luminescens Belongs to the Two-Partner Secretion Family of Hemolysins

Cited by 79 publications

References 51 publications

Genomic basis of endosymbiont-conferred protection against an insect parasitoid

Genomic basis of endosymbiont-conferred protection against an insect parasitoid

The genome sequence of the entomopathogenic bacterium Photorhabdus luminescens

A Novel Secreted Protein Toxin from the Insect Pathogenic Bacterium Xenorhabdus nematophila

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