scholarly journals Natural 2′,5′-Phosphodiester Bonds Found at the Ligation Sites of Peach Latent Mosaic Viroid

2001 ◽  
Vol 75 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Fabien Côté ◽  
Dominique Lévesque ◽  
Jean-Pierre Perreault
Keyword(s):  
Circular Rna ◽  
Rolling Circle ◽  
Phosphodiester Bonds ◽  
Biological Importance ◽  
Rolling Circle Mechanism ◽  
Ligation Site

ABSTRACT Peach latent mosaic viroid (PLMVd) is a circular RNA pathogen that replicates in a DNA-independent fashion via a rolling circle mechanism. PLMVd has been shown to self-ligate in vitro primarily via the formation of 2′,5′-phosphodiester bonds; however, in vivo the occurrence and necessity of this nonenzymatic mechanism are not evident. Here, we unequivocally report the presence of 2′,5′-phosphodiester bonds at the ligation site of circular PLMVd strands isolated from infected peach leaves. These bonds serve to close the linear conformers (i.e., intermediates), yielding circular ones. Furthermore, these bonds are shown to stabilize the replicational circular templates, resulting in a significant advantage in terms of viroid viability. Although the mechanism responsible for the formation of these 2′,5′-phosphodiester bonds remains to be elucidated, a hypothesis describing in vivo nonenzymatic self-ligation is proposed. Most significantly, our results clearly show that 2′,5′-phosphodiester bonds are still present in nature and that they are of biological importance.

scholarly journals Viroids: unusual small pathogenic RNAs.

2004 ◽  
Vol 51 (3) ◽  
pp. 587-607 ◽  
Author(s):  
Anna Góra-Sochacka
Keyword(s):  
Secondary Structure ◽  
Hammerhead Ribozyme ◽  
Direct Interaction ◽  
Plant Diseases ◽  
Plant Host ◽  
Rolling Circle ◽  
Rna Molecules ◽  
Viroid Replication ◽  
Plant Genes ◽  
Rolling Circle Mechanism

Viroids are small (about 300 nucleotides), single-stranded, circular, non-encapsidated pathogenic RNA molecules. They do not code for proteins and thus depend on plant host enzymes for their replication and other functions. They induce plant diseases by direct interaction with host factors but the mechanism of pathogenicity is still unknown. They can alter the expression of selected plant genes important for growth and development. Viroids belong to two families, the Avsunviroidae and the Pospiviroidae. Viroids of the Avsunviroidae family adopt a branched or quasi rod-like secondary structure in their native state. Members of the Pospiviroidae family adopt a rod-like secondary structure. In such native structures five structural/functional domains have been identified: central (C), pathogenicity, variable and two terminal domains. The central conserved region (CCR) within the C domain characterizes viroids of the Pospiviroidae. Specific secondary structures of this region play an important role in viroid replication and processing. Viroids of the Avsunviroidae family lack a CCR but possess self-cleaving properties by forming hammerhead ribozyme structures; they accumulate and replicate in chloroplasts, whereas members of the Pospiviroidae family have a nuclear localization. Viroid replication occurs via a rolling circle mechanism using either a symmetric or asymmetric pathway in three steps, RNA transcription, processing and ligation.

scholarly journals Autonomous Replication of the Conjugative Transposon Tn916

2016 ◽  
Vol 198 (24) ◽  
pp. 3355-3366 ◽  
Author(s):  
Laurel D. Wright ◽  
Alan D. Grossman
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Origin Of Replication ◽  
Rolling Circle Replication ◽  
Conjugative Transposon ◽  
Rolling Circle ◽  
Autonomous Replication ◽  
Integrative And Conjugative Elements ◽  
Rolling Circle Mechanism ◽  
Origin Of Transfer

ABSTRACTIntegrative and conjugative elements (ICEs), also known as conjugative transposons, are self-transferable elements that are widely distributed among bacterial phyla and are important drivers of horizontal gene transfer. Many ICEs carry genes that confer antibiotic resistances to their host cells and are involved in the dissemination of these resistance genes. ICEs reside in host chromosomes but under certain conditions can excise to form a plasmid that is typically the substrate for transfer. A few ICEs are known to undergo autonomous replication following activation. However, it is not clear if autonomous replication is a general property of many ICEs. We found that Tn916, the first conjugative transposon identified, replicates autonomously via a rolling-circle mechanism. Replication of Tn916was dependent on the relaxase encoded byorf20of Tn916. The origin of transfer of Tn916,oriT(916), also functioned as an origin of replication. Using immunoprecipitation and mass spectrometry, we found that the relaxase (Orf20) and the two putative helicase processivity factors (Orf22 and Orf23) encoded by Tn916likely interact in a complex and that the Tn916relaxase contains a previously unidentified conserved helix-turn-helix domain in its N-terminal region that is required for relaxase function and replication. Lastly, we identified a functional single-strand origin of replication (sso) in Tn916that we predict primes second-strand synthesis during rolling-circle replication. Together these results add to the emerging data that show that several ICEs replicate via a conserved, rolling-circle mechanism.IMPORTANCEIntegrative and conjugative elements (ICEs) drive horizontal gene transfer and the spread of antibiotic resistances in bacteria. ICEs reside integrated in a host genome but can excise to create a plasmid that is the substrate for transfer to other cells. Here we show that Tn916, an ICE with broad host range, undergoes autonomous rolling-circle replication when in the plasmid form. We found that the origin of transfer functions as a double-stranded origin of replication and identified a single-stranded origin of replication. It was long thought that ICEs do not undergo autonomous replication. Our work adds to the evidence that ICEs replicate autonomously as part of their normal life cycle and indicates that diverse ICEs use the same replicative mechanism.

pBMSa1, a plasmid from a dairy cow isolate of Staphylococcus aureus, encodes a lincomycin resistance determinant and replicates by the rolling-circle mechanism

Plasmid ◽  
2004 ◽  
Vol 52 (1) ◽  
pp. 48-56 ◽  
Author(s):  
Pedro D Loeza-Lara ◽  
Morelia Soto-Huipe ◽  
Victor M Baizabal-Aguirre ◽  
Alejandra Ochoa-Zarzosa ◽  
Juan J Valdez-Alarcón ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Dairy Cow ◽  
Resistance Determinant ◽  
Rolling Circle ◽  
Rolling Circle Mechanism ◽  
Lincomycin Resistance

scholarly journals Characteristic of plasmids of Bacillus pumilus isolated in Belarus

2019 ◽  
Vol 64 (3) ◽  
pp. 292-301
Author(s):  
O. V. Evdokimova ◽  
M. A. Chindareva ◽  
L. N. Valentovich
Keyword(s):  
Genetic Polymorphism ◽  
Bacillus Pumilus ◽  
Rolling Circle ◽  
Genetic Elements ◽  
Extrachromosomal Elements ◽  
Environmental Bacteria ◽  
Rolling Circle Mechanism

In current study plasmids (size from 6.2 to 8.5 kb) copied with the “rolling circle” mechanism (RCR type) of the pC194 family have been identified in environmental bacteria Bacillus pumilus. It is shown that these extrachromosomal elements are widely distributed in B. pumilus bacteria circulating on the territory of Belarus (19 strains from 41 contain RCRplasmids) and they are characterized by genetic polymorphism. The most common extrachromosomal genetic elements (7.7 kb size) are identical to the plasmid pBp15.1S from the entomopathogenic strain B. pumilus 15.1. The remaining 6 type of plasmids differ from each other and from the known extrachromosomal genetic elements of genus Bacillus. In the investigated bacteria no replicons similar to pLS20 were detected.

scholarly journals ICTV Virus Taxonomy Profile: Pospiviroidae

2020 ◽  
Author(s):  
Francesco Di Serio ◽  
Robert A. Owens ◽  
Shi-Fang Li ◽  
Jaroslav Matoušek ◽  
Vicente Pallás ◽  
...  
Keyword(s):  
Circular Rna ◽  
Virus Taxonomy ◽  
Hammerhead Ribozymes ◽  
Rolling Circle ◽  
Link Type ◽  
The Family ◽  
Rolling Circle Mechanism ◽  
Conserved Region

Members of the family Pospiviroidae have single-stranded circular RNA genomes that adopt a rod-like or a quasi-rod-like conformation. These genomes contain a central conserved region that is involved in replication in the nucleus through an asymmetric RNA–RNA rolling-circle mechanism. Members of the family Pospiviroidae lack the hammerhead ribozymes that are typical of viroids classified in the family Avsunviroidae. The family Pospiviroidae includes the genera Apscaviroid, Cocadviroid, Coleviroid, Hostuviroid and Pospiviroid, with >25 species. This is a summary of the ICTV Report on the family Pospiviroidae, which is available at ictv.global/report/pospiviroidae.

The Facts and Family Secrets of Plasmids That Replicate via the Rolling-Circle Mechanism

2021 ◽  
Author(s):  
M. Pilar Garcillán-Barcia ◽  
Radoslaw Pluta ◽  
Fabián Lorenzo-Díaz ◽  
Alicia Bravo ◽  
Manuel Espinosa
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Rolling Circle ◽  
Family Secrets ◽  
Dna Elements ◽  
Rolling Circle Mechanism

Plasmids are self-replicative DNA elements that are transferred between bacteria. Plasmids encode not only antibiotic resistance genes but also adaptive genes that allow their hosts to colonize new niches.

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