Occurrence of Intracellular Inclusions and Plasmids in Xenorhabdus spp.

Couche, Graham A.; Lehrbach, P. R.; Forage, R G; Cooney, G. C.; Smith, Daniel R.; Gregson, Richard P.

doi:10.1099/00221287-133-4-967

Cited by 20 publications

(22 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1987; Couche et al, 1987;Gregson & McInerney, 1985; To confirm that ppGpp induction is an obligatory step Paul et al, 1981 ; Rhodes et al, in the inhibition of RNA synthesis by the indole 1983; Richardson et al, 1988;Schmidt et al, 1988) antibiotic, its effect on the isogenic stringent and relaxed contribute to the success of the symbiotic relationship pair of E. coli K12 strains, NF161 and NF162 rewithin the microenvironment of the insect host. Among spectively, was investigated.…”

Section: Inhibition Of the Synthesis Of R N A And Proteinmentioning

confidence: 99%

Antimicrobial activity and biosynthesis of indole antibiotics produced by Xenorhabdus nematophilus

Sundar

Chang

1993

Journal of General Microbiology

View full text Add to dashboard Cite

~We have investigated the mechanism of action and physiology of production of the indole derivative antibiotics produced by the nematode-associated, entomopathogenic bacterium Xenorhabdus nernatophilus. Maximum antibiotic concentration was reached during the late stationary phase of growth, and the antibiotic yield was appreciably enhanced by supplementation with tryptophan. Antibiotic biosynthesis apparently involved the removal of the side-chain carboxyl (C-1) carbon of tryptophan. The C-3 methylene carbon of tryptophan, on the other hand, was retained. The purified indole antibiotic was effective against both Gram-positive and Gram-negative bacteria at low to moderate concentrations causing a severe inhibition of RNA synthesis, accompanied by a less severe effect on protein synthesis. An isogenic pair of Eschevichia coli strains differing at the velA locus was used to demonstrate that the swift reduction in total RNA synthesis is related to an antibiotic-induced accumulation of the regulatory nucleotide, ppGpp, in susceptible bacteria. The E. coli veZA mutant, which does not exhibit any discernible increase in ppGpp upon antibiotic treatment, showed no decrease in growth or RNA synthesis. Using this antibiotic, it was also observed that ppGpp may be employed as a metabolic regulator in bacteria such as Pseudomonasputida, which have not previously been reported to employ ppGpp as a regulatory molecule. We propose that the indole derivative antibiotic exerts growth inhibitory control in susceptible bacteria by greatly enhancing synthesis of ppGpp, resulting in a rapid inhibition of RNA synthesis.

show abstract

Section: Inhibition Of the Synthesis Of R N A And Proteinmentioning

confidence: 99%

Antimicrobial activity and biosynthesis of indole antibiotics produced by Xenorhabdus nematophilus

Sundar

Chang

1993

Journal of General Microbiology

View full text Add to dashboard Cite

show abstract

“…is not understood. No difference in plasmid composition between the two forms has been found (7,17). The structure of the bioluminescence (lux) genes has been found to be the same in the primary and secondary forms of the bacteria (10,23).…”

mentioning

confidence: 99%

Phase variation in Xenorhabdus luminescens: cloning and sequencing of the lipase gene and analysis of its expression in primary and secondary phases of the bacterium

Wang

Dowds

1993

J Bacteriol

View full text Add to dashboard Cite

The phenomenon of phase variation in the insect-pathogenic bacterium Xenorhabdus luminescens was investigated. Differential activity of the lipase enzyme (EC 3.1.1.3) was observed between the two phases of the bacteria. The enzyme was found to be secreted into the culture medium, and about five to six times greater specific activity was secreted by the primary phase than by the secondary form. The lipase gene (lip-1) was cloned and sequenced. The data imply that there is only a single Tween 80-utilizing lipase gene in X. luminescens K122. The sequence revealed a translation product of 645 amino acids, from which a hydrophobic leader sequence of 24 amino acids is removed during processing. The structure of the gene was shown to be the same in the primary and secondary forms of X. luminescens. In addition, transcription was found to start at the same position, 169 bp upstream of the translation initiation codon, in the two forms of the bacteria. Equal amounts of lipase RNA accumulated in the two forms, and at least as much lipase protein was secreted by the secondary form as by the primary. This suggests that the difference in specific activity between the enzymes secreted by the two phases probably arises from a posttranslational type of regulation.

show abstract

“…Boemare et al (7) suggested that Xenorhabdus inclusions may be similar to the protein crystals of B. thuringiensis as both organisms are associated with entomopathogenesis. However, we have been unable to demonstrate toxicity of intact or solubilized inclusions when administered to Heliothis punctigera or Lucilia cuprina by either feeding or injection (10). Furthermore, hemolytic activity such as that associated with the 28-kDa protein of the B. thuringiensis var.…”

Section: Discussionmentioning

confidence: 98%

“…A subsequent survey of 11 strains of X. nematophilus and 2 strains of Xenorhabdus luminescens showed that all isolates were capable of producing inclusions when grown on solid media. In liquid media, inclusion formation occurred only in primary-form X. nematophilus, in contrast to X. luminescens in which both primary and secondary forms produced inclusions (10). Intracellular inclusion bodies have also been described in several ultrastructural studies of Xenorhabdus spp.…”

mentioning

confidence: 84%

“…If the antibody response to such a determinant is very low in the IP-2-vaccinated rabbit, the extent of cross-reaction with IP-1 may be less than that required for detection in immunoblots. In dot blots, the lower detection limits for IP-1 and IP-2 with 10 ,ug of alkali-solubilized inclusion protein was detected by the anti-rabbit IgG-horseradish peroxidase method as described in Materials and Methods. (B) Sensitivity of alkaline phosphatase immunodetection procedure, using protein A-affinitypurified antisera, and cross-reactivity against SDS-denatured inclusion proteins.…”

Section: Downloaded Frommentioning

confidence: 99%

See 1 more Smart Citation

Protein inclusions produced by the entomopathogenic bacterium Xenorhabdus nematophilus subsp. nematophilus

Couche¹,

Gregson²

1987

J Bacteriol

View full text Add to dashboard Cite

The entomopathogenic bacterium Xenorhabdus nematophilus subsp. nematophilus produces two types of intracellular inclusion bodies during in vitro culture. Large cigar-shaped inclusions (designated type 1) and smaller ovoid inclusions (designated type 2) were purified from cell lysates, using differential centrifugation in discontinuous glycerol gradients and isopycnic density gradient centrifugation in sodium diatrizoate. The inclusions, composed almost exclusively of protein, are readily soluble at high and low pH values and in the presence of cation chelators such as EDTA, anionic detergents (sodium dodecyl sulfate), or protein denaturants (urea, NaBr). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified inclusions revealed a single 26-kilodalton protein (IP-1) in type 1 inclusions and a 22-kilodalton protein (IP-2) in type 2 inclusions. Analysis of these proteins by isoelectric focusing in the presence of 8 M urea showed that IP-1 is acidic and IP-2 is neutral. Furthermore, each protein occurred in multiple forms differing slightly in isoelectric point. Other variations in peptides released by trypsin digestion, immunological properties, and amino acid composition revealed significant structural differences between IP-1 and IP-2. Kinetic studies using light microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunoblotting procedures showed that inclusion protein synthesis occurs only during the second half of exponential culture growth. Synthesis of inclusion proteins and their aggregation to form inclusions occurred concurrently. Possible functions for these abundant proteins are discussed.Xenorhabdus species are entomopathogenic bacteria symbiotically associated with insect parasitic nematodes of the families Heterorhabditidae and Steinernematidae (1,3,30). The bacterial symbionts are asporogenous gram-negative rods, which are carried monoxenically in the intestine of nonfeeding infective-stage nematodes. On penetration of an insect host, the bacteria are released into the hemocoel. Colonization by the bacteria kills the host and establishes a suitable environment for reproduction of the nematodes by providing nutrients and inhibiting the growth of other microorganisms (1,24).When cultured in vitro, Xenorhabdus bacteria occur in two forms designated primary and secondary, which can be distinguished according to colony morphology and pigmentation on various bacteriological media, or on the basis of antibiotic production (1, 2). Both forms are pathogenic to insects, but only the primary form is isolated from infective nematodes (1). Xenorhabdus spp. will grow in a wide variety of artificial media which are rendered suitable for nematode reproduction, thus providing the basis for economical mass production of nematodes. Our nematophilus, in contrast to X. luminescens in which both primary and secondary forms produced inclusions (10). Intracellular inclusion bodies have also been described in several ultrastructural studies of Xenorhabdus spp. (4,7,15,18).In this repor...

show abstract

Occurrence of Intracellular Inclusions and Plasmids in Xenorhabdus spp.

Cited by 20 publications

References 14 publications

Antimicrobial activity and biosynthesis of indole antibiotics produced by Xenorhabdus nematophilus

Antimicrobial activity and biosynthesis of indole antibiotics produced by Xenorhabdus nematophilus

Phase variation in Xenorhabdus luminescens: cloning and sequencing of the lipase gene and analysis of its expression in primary and secondary phases of the bacterium

Protein inclusions produced by the entomopathogenic bacterium Xenorhabdus nematophilus subsp. nematophilus

Contact Info

Product

Resources

About