Genetic and biochemical characterization of PrtA, an RTX-like metalloprotease from Photorhabdus

Bowen, David; Rocheleau, Thomas A.; Grutzmacher, Cathy; Meslet, Laurence; Valens, Michelle; Marble, D.K.; Dowling, Andrea J.; ffrench-Constant, Richard H.; Blight, Mark A.

doi:10.1099/mic.0.26171-0

Cited by 57 publications

(65 citation statements)

References 45 publications

(39 reference statements)

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“…In addition to degrading AMPs, proteases might be involved in the destruction of cells and tissues to facilitate colonization of the insect body 69 . During symbiotic associations between bacterial entomopathogens and nematodes, proteases might also provide nutrients to their nematode hosts 70 , which multiply in the dead insect body.…”

Section: Box 3 | Heritable Microorganismsmentioning

confidence: 99%

Bacterial strategies to overcome insect defences

2008

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| Recent genetic and molecular analyses have revealed how several strategies enable bacteria to persist and overcome insect immune defences. Genetic and genomic tools that can be used with Drosophila melanogaster have enabled the characterization of the pathways that are used by insects to detect bacterial invaders and combat infection. Conservation of bacterial virulence factors and insect immune repertoires indicates that there are common strategies of host invasion and pathogen eradication. Long-term interactions of bacteria with insects might ensure efficient dissemination of pathogens to other hosts, including humans. R E V I E W S302 | APRIL 2008 | voLUME 6 www.nature.com/reviews/micro

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Section: Box 3 | Heritable Microorganismsmentioning

confidence: 99%

Bacterial strategies to overcome insect defences

2008

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“…A decade ago, bioinformatic studies predicted a set of genes that code for a putative T1SS in Legionella, but the functionality of such a system has never been demonstrated (14). The implication of T1SSs in the virulence of pathogenic bacteria, such as uropathogenic Escherichia coli (UPEC), Bordetella pertussis, or even the entomopathogen Photorhabdus, was demonstrated many years ago (15)(16)(17). To date, the most extensively studied examples of T1SSs are the Hly system in UPEC (18), the Apr system in Pseudomonas aeruginosa (19), and the Prt system in Dickeya dadantii (20).…”

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confidence: 99%

Functional Type 1 Secretion System Involved in Legionella pneumophila Virulence

et al. 2014

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e Legionella pneumophila is a Gram-negative pathogen found mainly in water, either in a free-living form or within infected protozoans, where it replicates. This bacterium can also infect humans by inhalation of contaminated aerosols, causing a severe form of pneumonia called legionellosis or Legionnaires' disease. The involvement of type II and IV secretion systems in the virulence of L. pneumophila is now well documented. Despite bioinformatic studies showing that a type I secretion system (T1SS) could be present in this pathogen, the functionality of this system based on the LssB, LssD, and TolC proteins has never been established. Here, we report the demonstration of the functionality of the T1SS, as well as its role in the infectious cycle of L. pneumophila. Using deletion mutants and fusion proteins, we demonstrated that the repeats-in-toxin protein RtxA is secreted through an LssB-LssD-TolC-dependent mechanism. Moreover, fluorescence monitoring and confocal microscopy showed that this T1SS is required for entry into the host cell, although it seems dispensable to the intracellular cycle. Together, these results underline the active participation of L. pneumophila, via its T1SS, in its internalization into host cells.

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“…By releasing several toxins (6, 12, 18), the bacteria rapidly kill the larvae and multiply to large numbers (14). This virulence phase is followed, as the bacteria reach stationary phase, by the secretion of many hydrolytic enzymes (proteases [13,15,40], lipase [42], phospholipase, and DNase) and other enzymes, which degrade the macromolecular structures of the larva. This phase, which can be called the bioconversion phase, is essential for the development and reproduction of the hermaphrodite nematode (11,15).…”

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confidence: 99%

In Vivo Expression of the Mannose-Resistant Fimbriae of Photorhabdus temperata K122 during Insect Infection

et al. 2004

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Photorhabdus temperata K122 is an entomopathogenic bacterium symbiotically associated with nematodes of the family Heterorhabditidae. Surface fimbriae are important for the colonization of many pathogenic bacteria, and here we report the nucleotide sequence and analysis of the expression of a 12-kbp fragment encoding the mannose-resistant fimbriae of P. temperata (mrf). The mrf gene cluster contains 11 genes with an organization similar to that of the mrp locus from Proteus mirabilis. mrfI (encoding a putative recombinase) and mrfA (encoding pilin), the first gene in an apparent operon of nine other genes, are expressed from divergent promoters. The mrfI-mrfA intergenic region contains inverted repeats flanking the mrfA promoter. This region was shown to be capable of inversion, consistent with an ON/OFF regulation of the operon. In in vitro liquid cultures, both orientations were detected. Nevertheless, when we analyzed the expression of all of the genes in the mrf locus by semiquantitative reverse transcription-PCR during infection of Galleria mellonella (greater wax moth) larvae, expression of mrfA was not detected until 25 h postinfection, preceding the death of the larvae at 32 h. In contrast, mrfJ (a putative inhibitor of flagellar synthesis) was expressed throughout infection. Expression of mrfI was also detected only late in infection (25 to 30 h), indicating a possible increase in inversion frequency at this stage. In both in vitro liquid cultures and in vivo larval infections, the distal genes of the operon were expressed at substantially lower levels than mrfA. These results indicate the complex regulation of the mrf cluster during infection.Photorhabdus luminescens K122 is a gram-negative insect pathogen belonging to the gamma subdivision of the Enterobacteriaceae (10,16,38,39). In a recent reclassification, P. luminescens K122 was renamed Photorhabdus temperata (19). Despite the fact that it is a pathogen to insects, P. temperata also forms a natural symbiotic association in the intestines of nematodes of the family Heterorhabditidae (20). P. temperata presents numerous advantages as a model system for the study of both symbiosis and virulence in the same organism, since the bacteria and the nematode together constitute a highly efficient pathogenic interaction with a broad host range of insects.For initiation of the pathogenic process, the nematode transports the bacteria into the interior of insect larvae, where they are released into the hemolymph. By releasing several toxins (6, 12, 18), the bacteria rapidly kill the larvae and multiply to large numbers (14). This virulence phase is followed, as the bacteria reach stationary phase, by the secretion of many hydrolytic enzymes (proteases [13,15,40], lipase [42], phospholipase, and DNase) and other enzymes, which degrade the macromolecular structures of the larva. This phase, which can be called the bioconversion phase, is essential for the development and reproduction of the hermaphrodite nematode (11,15). In addition, during the bioconversion pha...

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Genetic and biochemical characterization of PrtA, an RTX-like metalloprotease from Photorhabdus

Cited by 57 publications

References 45 publications

Bacterial strategies to overcome insect defences

Bacterial strategies to overcome insect defences

Functional Type 1 Secretion System Involved in Legionella pneumophila Virulence

In Vivo Expression of the Mannose-Resistant Fimbriae of Photorhabdus temperata K122 during Insect Infection

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