R-body-producing bacteria.

Pond, F R; Gibson, I; Lalucat, J; Quackenbush, Robert L.

doi:10.1128/mmbr.53.1.25-67.1989

Cited by 54 publications

(31 citation statements)

References 86 publications

(215 reference statements)

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“…Within this cluster, the three Acanthamoeba endosymbionts are most closely related to Caedibacter caryophilus, previously known as kappa particle (Springer et al, 1993). The genus Caedibacter is currently de®ned and characterized on the basis of morphological and physiological properties (Pond et al, 1989): ®ve species have been described as Gram-negative, non-spore-forming, non-motile, facultative anaerobic, Rbody (refractile inclusion body)-producing, obligate endosymbionts of Paramecium tetraurelia, P. biaurelia and P. caudatum. Whereas C. taeniospiralis, C. varicaedens, C. pseudomutans and C. paraconjugatus are located in the cytoplasm of their host species, C. caryophilus is a macronuclear endosymbiont of P. caudatum.…”

Section: Discussionmentioning

confidence: 99%

“…Only the latter endosymbiont species has yet been characterized phylogenetically by 16S rRNA analysis. There seems, however, to be considerable phylogenetic diversity within the genus Caedibacter as indicated by DNA±DNA hybridization studies (Pond et al, 1989.). To date, it is not possible to predict whether the Acanthamoeba endosymbionts are closely related to those Caedibacter species for which no 16S rDNA sequence information is available.…”

Section: Discussionmentioning

confidence: 99%

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Novel bacterial endosymbionts of Acanthamoeba spp. related to the Paramecium caudatum symbiont Caedibacter caryophilus

Horn

Fritsche

Gautom

et al. 1999

Environmental Microbiology

186

135

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Acanthamoebae are increasingly being recognized as hosts for obligate bacterial endosymbionts, most of which are presently uncharacterized. In this study, the phylogeny of three Gram-negative, rod-shaped endosymbionts and their Acanthamoeba host cells was analysed by the rRNA approach. Comparative analyses of 16S rDNA sequences retrieved from amoebic cell lysates revealed that the endosymbionts of Acanthamoeba polyphaga HN-3, Acanthamoeba sp. UWC9 and Acanthamoeba sp. UWE39 are related to the Paramecium caudatum endosymbionts Caedibacter caryophilus, Holospora elegans and Holospora obtusa. With overall 16S rRNA sequence similarities to their closest relative, C. caryophilus, of between 87% and 93%, these endosymbionts represent three distinct new species. In situ hybridization with fluorescently labelled endosymbiont-specific 16S rRNA-targeted probes demonstrated that the retrieved 16S rDNA sequences originated from the endosymbionts and confirmed their intracellular localization. We propose to classify provisionally the endosymbiont of Acanthamoeba polyphaga HN-3 as 'Candidatus Caedibacter acanthamoebae', the endosymbiont of Acanthamoeba sp. strain UWC9 as 'Candidatus Paracaedibacter acanthamoebae' and the endosymbiont of Acanthamoeba sp. strain UWE39 as 'Candidatus Paracaedibacter symbiosus'. The phylogeny of the Acanthamoeba host cells was analysed by comparative sequence analyses of their 18S rRNA. Although Acanthamoeba polyphaga HN-3 clearly groups together with most of the known Acanthamoeba isolates (18S rRNA sequence type 4), Acanthamoeba sp. UWC9 and UWE39 exhibit <92% 18S rRNA sequence similarity to each other and to other Acanthamoeba isolates. Therefore, we propose two new sequence types (T13 and T14) within the genus Acanthamoeba containing, respectively, Acanthamoeba sp. UWC9 and Acanthamoeba sp. UWE39.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Novel bacterial endosymbionts of Acanthamoeba spp. related to the Paramecium caudatum symbiont Caedibacter caryophilus

Horn

Fritsche

Gautom

et al. 1999

Environmental Microbiology

186

135

View full text Add to dashboard Cite

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“…syringae B728a and P. brassicacearum are also regulated by the Gac/Rsm system (Records and Gross, 2010;Lalaouna et al, 2012). RebB proteins form refractile inclusion bodies (R-bodies) that have been associated with toxicity to paramecia when produced by obligate symbionts in the genus Caedibacter (Pond et al, 1989). R-bodies have been reported in some Pseudomonas spp., but their biological function in the genus is unknown (Lalucat et al, 1982;Wells and Horne, 1983;Espuny et al, 1991).…”

Section: Gaca Regulation Of Type VI Secretion and Rebb Proteinsmentioning

confidence: 99%

Genes expressed by the biological control bacterium Pseudomonas protegens Pf‐5 on seed surfaces under the control of the global regulators GacA and RpoS

Kidarsa

Shaffer

Goebel

et al. 2013

Environmental Microbiology

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Gene expression profiles of the biological control strain Pseudomonas protegens Pf-5 inhabiting pea seed surfaces were revealed using a whole-genome oligonucleotide microarray. We identified genes expressed by Pf-5 under the control of two global regulators (GacA and RpoS) known to influence biological control and secondary metabolism. Transcript levels of 897 genes, including many with unknown functions as well as those for biofilm formation, cyclic diguanylate (c-di-GMP) signalling, iron homeostasis and secondary metabolism, were influenced by one or both regulators, providing evidence for expression of these genes by Pf-5 on seed surfaces. Comparison of the GacA and RpoS transcriptomes defined for Pf-5 grown on seed versus in broth culture overlapped, but most genes were regulated by GacA or RpoS under only one condition, likely due to differing levels of expression in the two conditions. We quantified secondary metabolites produced by Pf-5 and gacA and rpoS mutants on seed and in culture, and found that production profiles corresponded generally with biosynthetic gene expression profiles. Future studies evaluating biological control mechanisms can now focus on genes expressed by Pf-5 on seed surfaces, the habitat where the bacterium interacts with seed-infecting pathogens to suppress seedling diseases.

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“…Type 51 R bodies are just one among several described types of R bodies, all of which have been 191 reported to have varied properties (reviewed in (1) biotin, Thermo Fisher Scientific) were added and left to incubate for 5 minutes. The chambers were 240 washed with more PBS followed by 1mg/ml BSA/BSA-biotin solution.…”

Section: Figure 3: a Visual Screen For Mutants Defective In Ph Responmentioning

confidence: 99%

Tuning microscale, retractable, membrane-breaking protein needles

Polka

Silver

2015

Preprint

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10The refractile (R) bodies found in Caedibacter taeniospiralis, a bacterial endosymbiont of Paramecium 11 tetraurelia, are large, polymeric protein structures that can switch between two conformations. At 12 cytoplasmic pH, they resemble coiled ribbons of protein 500nm in diameter. At low pH, they extend to 13 form hollow needles up to 20 microns long. They can be expressed heterologously from an operon 14containing four short open reading frames and can function in vitro in diverse buffer conditions. 15In this study, R bodies purified from Escherichia coli were found to be capable of undergoing many 16 consecutive extension-contraction cycles. Furthermore, the solubility of R bodies, which can easily be 17 interpreted by eye, was found to correlate with their extension state. This macroscopic phenotype was 18 used to develop a quantitative, high-throughput assay for R body state, enabling a visual screen of R 19 body mutants defective in extension. The role of specific amino acids in extension was determined, and 20 this information was used to construct rationally-designed mutants tailored to extend at higher pH. acidic conditions (such as those encountered when ingested by a eukaryotic cell), they dramatically 28 extend into a long, hollow tube that can disrupt membranes. R bodies are made from only four small 29 proteins, function independently of cells, and can withstand harsh conditions. As such, they hold 30 promise as tools to facilitate gene or drug delivery. 31Here we show the R body extension process is reversible over many cycles and that R bodies are capable 32 of releasing E. coli cell contents into the environment. Furthermore, we generated a panel of mutant R 33 bodies that extend at varying pH values. These mutants demonstrate that R bodies can be tuned to 34 function in specific applications. 35

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R-body-producing bacteria.

Cited by 54 publications

References 86 publications

Novel bacterial endosymbionts of Acanthamoeba spp. related to the Paramecium caudatum symbiont Caedibacter caryophilus

Novel bacterial endosymbionts of Acanthamoeba spp. related to the Paramecium caudatum symbiont Caedibacter caryophilus

Genes expressed by the biological control bacterium Pseudomonas protegens Pf‐5 on seed surfaces under the control of the global regulators GacA and RpoS

Tuning microscale, retractable, membrane-breaking protein needles

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