This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Pond, F R Articles by Quackenbush, R L Search for Related Content PubMed PubMed Citation Articles by Pond, F R Articles by Quackenbush, R L

R-body-producing bacteria.

SUMMARY

Until 10 years ago, R bodies were known only as diagnostic features by which endosymbionts of paramecia were identified as kappa particles. They were thought to be limited to the cytoplasm of two species in the Paramecium aurelia species complex. Now, R bodies have been found in free-living bacteria and other Paramecium species. The organisms now known to form R bodies include the cytoplasmic kappa endosymbionts of P. biaurelia and P. tetraurelia, the macronuclear kappa endosymbionts of P. caudatum, Pseudomonas avenae (a free-living plant pathogen), Pseudomonas taeniospiralis (a hydrogen-oxidizing soil microorganism), Rhodospirillum centenum (a photosynthetic bacterium), and a soil bacterium, EPS-5028, which is probably a pseudomonad. R bodies themselves fall into five distinct groups, distinguished by size, the morphology of the R-body ribbons, and the unrolling behavior of wound R bodies. In recent years, the inherent difficulties in studying the organization and assembly of R bodies by the obligate endosymbiont kappa, have been alleviated by cloning and expressing genetic determinants for these R bodies (type 51) in Escherichia coli. Type 51 R-body synthesis requires three low-molecular-mass polypeptides. One of these is modified posttranslationally, giving rise to 12 polypeptide species, which are the major structural subunits of the R body. R bodies are encoded in kappa species by extrachromosomal elements. Type 51 R bodies, produced in Caedibacter taeniospiralis, are encoded by a plasmid, whereas bacteriophage genomes probably control R-body synthesis in other kappa species. However, there is no evidence that either bacteriophages or plasmids are present in P. avenae or P. taeniospiralis. No sequence homology was detected between type 51 R-body-encoding DNA and DNA from any R-body-producing species, except C. varicaedens 1038. The evolutionary relatedness of different types of R bodies remains unknown.

This article has been cited by other articles:

• Gottesman, M. E., Weisberg, R. A. (2004). Little Lambda, Who Made Thee?. Microbiol. Mol. Biol. Rev. 68: 796-813 [Abstract] [Full Text]  
• Greub, G., Raoult, D. (2004). Microorganisms Resistant to Free-Living Amoebae. Clin. Microbiol. Rev. 17: 413-433 [Abstract] [Full Text]  
• Hernandez-Romero, D., Lucas-Elio, P., Lopez-Serrano, D., Solano, F., Sanchez-Amat, A. (2003). Marinomonas mediterranea is a lysogenic bacterium that synthesizes R-bodies. Microbiology 149: 2679-2686 [Abstract] [Full Text]  
• Beier, C. L., Horn, M., Michel, R., Schweikert, M., Gortz, H.-D., Wagner, M. (2002). The Genus Caedibacter Comprises Endosymbionts of Paramecium spp. Related to the Rickettsiales (Alphaproteobacteria) and to Francisella tularensis (Gammaproteobacteria). Appl. Environ. Microbiol. 68: 6043-6050 [Abstract] [Full Text]