Transposonlike elements in Caedibacter taeniospiralis

Quackenbush, Robert L.; Dilts, Judith A.; Cox, Betty Jo

doi:10.1128/jb.166.1.349-352.1986

Cited by 15 publications

(12 citation statements)

References 11 publications

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“…The polypeptides produced during a 3-min pulse and a 6-h chase can be separated into four groups. In group 1 polypeptides, the relative amounts remain constant throughout the chase period (10 kDa, 18 kDa, and ,-lactamase). In group 2 polypeptides, the relative amounts decrease during the chase period (13 kDa).…”

Section: Methodsmentioning

confidence: 99%

“…Type 51 R bodies naturally occur only in C. taeniospiralis. The R body-coding plasmids in all strains of C. taeniospiralis exhibit no detectable differences with respect to distribution of restriction endonuclease recognition sites within their R body-coding sequences (16,18). In addition to the R body-coding sequence of pKAP47, which is contained in pBQ65, the R body-coding sequence of pKAP116 has also been cloned and extensively mapped by restriction enzyme analysis.…”

Section: Discussionmentioning

confidence: 99%

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Organization and expression of genetic determinants for synthesis and assembly of type 51 R bodies

Kanabrocki¹,

Quackenbush²,

Pond³

1986

J Bacteriol

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Type 51 R bodies are produced by all bacterial endosymbionts (Caedibacter taeniospiralis) of Paramecium tetraurelia that confer the hump-killer trait upon their hosts. Type 51 R-body synthesis by C. taeniospiralis is required for expression of the hump-killer trait. The genetic determinants for type 51 R-body synthesis by C. taeniospiralis 47 have been cloned and expressed in Escherichia coli. In this communication we describe three species of polypeptides required for R-body synthesis and the organization of their genetic determinants. Each polypeptide species is controlled by a separate gene that is expressed as an independent transcriptional unit possessing regulatory signals that are recognized by E. coli. Two polypeptide species of 10 and 18 kilodaltons are required for R-body synthesis but apparently are not structural subunits. The third polypeptide species (13 kilodaltons) is the major structural subunit. R-body assembly involves polymerization reactions that result in high-molecular-mass polypeptide complexes, primarily composed of the 13-kilodalton polypeptide species, that appear to be the result of covalent cross-linking between structural subunits. The results presented here have been suggested to apply to the assembly and structure of all type 51 R bodies, but not necessarily to other R-body types.Bacterial endosymbionts commonly occur in various species of Paramecium. The most notable group of these bacteria comprise the genus Caedibacter, more commonly known as kappa or kappa particles. These bacteria are easily distinguished from other symbionts by their ability to produce refractile inclusion bodies known as R bodies. An R body is a proteinaceous ribbon (approximately 10 to 20 ,um long, 0.5 ,um wide, and 13 nm thick) that is rolled up inside the bacterial cell, appearing as a hollow cylindical structure (1) (Fig. 1). Within any given population of Caedibacter species only a fraction of the individuals possess R bodies. R body-containing forms of Caedibacter species are toxic to sensitive strains of paramecia. Thus, paramecia that carry any Caedibacter strain are referred to as killers. Killer paramecia apparently release some of their endosymbionts into the environment when food vacuoles are emptied via the cytopyge (15). Killing occurs after an R body-containing symbiont is ingested by a sensitive paramecium.In three of the four species of Caedibacter, R-body synthesis appears to be determined by extrachromosomal elements that are thought to be defective bacteriophages (15). In the fourth species, Caedibacter taeniospiralis, Rbody synthesis is determined by plasmids (17). R bodies produced by C. taeniospiralis, type 51 R bodies, are distinguished from those produced by the other species of Caedibacter on the basis of morphology and their response to changes in pH. Type 51 R-body ribbons typically end in acute angles and unroll from the inside, in a telescoping fashion, when the pH is lowered to 6.5 or less. Loss of the ability to assemble type 51 R bodies by C. taeniospiralis is accompanied by...

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Section: Methodsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Organization and expression of genetic determinants for synthesis and assembly of type 51 R bodies

Kanabrocki¹,

Quackenbush²,

Pond³

1986

J Bacteriol

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“…The transposon Tn4503 was known previously to be close to the reb locus of pKAP47 (24,25). This study and the work of Hodel-Christian (5) ORF that would encode smaller polypeptides (74 residues, 0.279; 82 residues, 0.265) are actually higher than those for the complete ORF (105 residues).…”

Section: Resultsmentioning

confidence: 76%

“…Even more puzzling is the observation that the R body-coding plasmid (pKAPl169) from C. taeniospiralis 169 (isolated in Japan) has the same restriction enzyme map as pKAP116 (25). The geographic distribution of these strictly freshwater, non-cystforming organisms suggests that the various strains have been isolated for countless generations.…”

Section: T T T S T a D V G N T T D I V N S Q I T D S V T Q Tmentioning

confidence: 99%

“…6C). DISCUSSION DNA hybridization, restriction endonuclease mapping, and immunological studies had previously demonstrated strong similarities among pKAP plasmids (20,25) and among type 51 R bodies (7,15) from various strains of C. taeniospiralis. This study was undertaken with the expectation that some differences may exist between the DNA sequences of the reb locus from the two strains studied.…”

Section: T T T S T a D V G N T T D I V N S Q I T D S V T Q Tmentioning

confidence: 99%

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Characterization of genetic determinants for R body synthesis and assembly in Caedibacter taeniospiralis 47 and 116

et al. 1994

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Caedibacter taeniospiralis, an obligate bacterial endosymbiont ofParamecium tetraurelia, confers a killing trait upon its host paramecium. Type 51 R bodies (refractile inclusion bodies) are synthesized by these endosymbionts and are required for expression of the killing trait. The nucleotide sequence of the genetic determinants for type 51 R body synthesis and assembly was determined for C. taeniospiralis 47 and 116. Three independently transcribed genes (rebA, rebB, and rebC) were characterized. To date these are the only genes from C. taeniospiralis to be sequenced and characterized. DNA regulatory regions are recognized by Escherichia coli, and codon usage appears similar to that in E. coli. A fourth open reading frame with appropriate regulatory sequences was found within the reb locus, but no evidence was obtained to suggest that this putative gene is expressed in E. coli. The R body-encoding sequences from both strains are identical. Two-dimensional gel electrophoresis of deletion derivatives shows that two polymerization events are involved in R body assembly. One polymerization event requires only RebB and RebC; the other requires all three proteins. Expression of RebC is necessary for the posttranslational modification of RebA and RebB into species with three and two different molecular weights, respectively. In the presence of RebC, each species of RebB with a different molecular weight has six different isoelectric points.Refractile inclusion bodies, known as R bodies, are produced by only a few species of bacteria. These inclusion bodies are highly insoluble protein ribbons, typically seen coiled into cylindrical structures within the cell. Five classes or types of R bodies have been described and are distinguished on the basis of physical dimensions, morphology, and behavior in response to certain physical and chemical treatments (16,21,22).Several classes of R bodies are produced by Caedibacter species, more commonly known as kappa particles. Caedibacter species are obligate bacterial endosymbionts of Paramecium species and are characterized by their ability to produce both R bodies and a toxin. R body-containing forms of Caedibacter species are toxic to sensitive strains of paramecia. Thus, paramecia that carry any Caedibacter strain are referred to as killers. Killing occurs when a sensitive paramecium ingests an R body-containing kappa particle that has been released into the environment by a killer paramecium (6).Five Caedibacter species, producing three of the five known types of R bodies (types 7, 51, and Cc [18,19]), have been identified. R body synthesis in four of the species is determined by extrachromosomal elements thought to be defective phages (17). In the fifth species, Caedibacter taeniospiralis, R body synthesis is directed by plasmid DNA (23). The R bodies of C. taeniospiralis are type 51. They are 0.4 p.m wide, have a maximum length of 20 ,um, possess acute angles at each end, and unroll in a telescopic fashion when exposed to a pH of 6.5 or lower.The R body-encoding region from...

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Towards an Understanding of the Killer Trait: Caedibacter endocytobionts in Paramecium

Kusch

Görtz

2005

Progress in Molecular and Subcellular Biology

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Transposonlike elements in Caedibacter taeniospiralis

Cited by 15 publications

References 11 publications

Organization and expression of genetic determinants for synthesis and assembly of type 51 R bodies

Organization and expression of genetic determinants for synthesis and assembly of type 51 R bodies

Characterization of genetic determinants for R body synthesis and assembly in Caedibacter taeniospiralis 47 and 116

Towards an Understanding of the Killer Trait: Caedibacter endocytobionts in Paramecium

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