Splicing of Cauliflower mosaic virus 35S RNA serves to downregulate a toxic gene product

Froissart, Rémy; Uzest, Marilyne; Ruiz‐Ferrer, Virginia; Drucker, Martin; Hébrard, Eugénie; Höhn, Thomas; Blanc, Stéphane

doi:10.1099/vir.0.80029-0

Cited by 20 publications

(31 citation statements)

References 34 publications

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“…This plasmid is not infectious when inoculated into turnip plants unless the stop codon reverts to a coding nucleotide triplet; that infectious revertants appear spontaneously upon Top-S inoculation has been reported previously (13). Several infectious revertants were characterized and are described in Results.…”

Section: Methodsmentioning

confidence: 72%

“…Laboratory colonies of all aphid species were initiated from a single viviparous aptera collected on cauliflower (B. Plasmid construction and mutagenesis. Clone pCa37 is the reference clone for the CaMV isolate Cabb-S (12); clone ⌬II-S, where the entire coding sequence of gene II is replaced by the unique restriction site SpeI, was described elsewhere (13).…”

Section: Methodsmentioning

confidence: 99%

“…Plasmid Top-S, containing the full genome-length CaMV Cabb-S sequence with an engineered early stop codon at amino acid position 6 of P2, was described previously (13). This plasmid is not infectious when inoculated into turnip plants unless the stop codon reverts to a coding nucleotide triplet; that infectious revertants appear spontaneously upon Top-S inoculation has been reported previously (13).…”

Section: Methodsmentioning

confidence: 99%

“…Several infectious revertants were characterized and are described in Results. To ensure that these revertants were not a mixed population, viral genomes were extracted from an infected plant as described previously (13) and cloned in pUC19 using the unique SalI restriction site in the CaMV sequence. The nature of the reversion of the stop codon at amino acid position 6 of P2 was determined by sequencing the various clones produced.…”

Section: Methodsmentioning

confidence: 99%

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A Single Amino Acid Position in the Helper Component of Cauliflower Mosaic Virus Can Change the Spectrum of Transmitting Vector Species

Moreno

Hébrard

Uzest

et al. 2005

J Virol

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Viruses frequently use insect vectors to effect rapid spread through host populations. In plant viruses, vector transmission is the major mode of transmission, used by nearly 80% of species described to date. Despite the importance of this phenomenon in epidemiology, the specificity of the virus-vector relationship is poorly understood at both the molecular and the evolutionary level, and very limited data are available on the precise viral protein motifs that control specificity. Here, using the aphid-transmitted Cauliflower mosaic virus (CaMV) as a biological model, we confirm that the "noncirculative" mode of transmission dominant in plant viruses (designated "mechanical vector transmission" in animal viruses) involves extremely specific virus-vector recognition, and we identify an amino acid position in the "helper component" (HC) protein of CaMV involved in such recognition. Site-directed mutagenesis revealed that changing the residue at this position can differentially affect transmission rates obtained with various aphid species, thus modifying the spectrum of vector species for CaMV. Most interestingly, in a virus line transmitted by a single vector species, we observed the rapid appearance of a spontaneous mutant specifically losing its transmissibility by another aphid species. Hence, in addition to the first identification of an HC motif directly involved in specific vector recognition, we demonstrate that change of a virus to a different vector species requires only a single mutation and can occur rapidly and spontaneously.

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Section: Methodsmentioning

confidence: 72%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

A Single Amino Acid Position in the Helper Component of Cauliflower Mosaic Virus Can Change the Spectrum of Transmitting Vector Species

Moreno

Hébrard

Uzest

et al. 2005

J Virol

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“…The shunt mechanism allows ribosomes to reach the start codon of gene VII. The subsequent expression of genes I through V on the 35S RNA involves alternative mechanisms, including transactivation of the translation of genes I through V by the CaMV gene VI product (18,44) and splicing (14,28).…”

mentioning

confidence: 99%

The Ribosomal Shunt Translation Strategy of Cauliflower Mosaic Virus Has Evolved from Ancient Long Terminal Repeats

Shababi

Bourque

Palanichelvam

et al. 2006

J Virol

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We have screened portions of the large intergenic region of the Cauliflower mosaic virus (CaMV) genome for promoter activity in baker's yeast (Saccharomyces cerevisiae) and have identified an element that contributes to promoter activity in yeast but has negligible activity in plant cells when expressed in an agroinfiltration assay. A search of the yeast genome sequence revealed that the CaMV element had sequence similarity with the R region of the long terminal repeat (LTR) of the yeast Ty1 retrotransposon, with significant statistical confidence. In plants, the same CaMV sequence has been shown to have an essential role in the ribosomal shunt mechanism of translation, as it forms the base of the right arm of the stem-loop structure that is required for the ribosomal shunt. Since the left arm of the stem-loop structure must represent an imperfect reverse copy of the right arm, we propose that the ribosomal shunt has evolved from a pair of LTRs that have become incorporated end to end into the CaMV genome.Cauliflower mosaic virus (CaMV), the type member of the caulimovirus group, is a pararetrovirus; it replicates by reverse transcription, but replication does not require the integration of the CaMV genome into host chromosomes. The lack of an integration step is one feature that distinguishes the replication strategy of CaMV from that of other plant retrotransposons or the animal retroviruses, and this is reflected in the structure of the CaMV genome (50). The CaMV genome is composed of circular, double-stranded DNA that is approximately 8,000 bp in size (Fig. 1A). The replication intermediate that serves as the template for reverse transcription is the CaMV 35S RNA (Fig. 1A) (47). The 35S RNA is formed when the host RNA polymerase II initiates transcription at nucleotide (nt) position 7435. A transcript termination signal at nucleotide 7613 is initially bypassed such that the RNA Pol II synthesizes viral RNA over the full length of the viral genome until it reaches the transcript termination signal for a second time, at which point transcription stops. Consequently, the first 179 bp of the 5Ј end of the 35S RNA are reiterated on the 3Ј end of the 35S RNA (50).The terminal redundancy in the 35S RNA is required for the template switch that occurs during the synthesis of the first strand of viral DNA by the CaMV reverse transcriptase. In this capacity, the terminal redundancies of the 35S RNA fulfill the function of the R region present in the long terminal repeats (LTRs) of retrotransposons and retroviruses. The structure and function of LTRs are most easily visualized in the retrotransposon forms that are integrated into host chromosomes (Fig. 1B). For example, the integrated form of Ty1 consists of two complete LTRs that flank the open reading frames (ORFs), and each of the LTRs is composed of three distinct regions: U3, R, and U5 (4, 5, 13). Transcription is initiated within the leftward LTR at the junction of U3 and R and is terminated at the junction of R and U5 in the rightward LTR (Fig. 1B). The resultant...

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Caulimoviridae (Plant Pararetroviruses)

Geering

2014

Encyclopedia of Life Sciences

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Family Caulimoviridae comprises seven genera of plant viruses whose members replicate by reverse transcription and whose virions contain double‐stranded deoxyribonucleic acid . In a recent survey of the international scientific community, Cauliflower mosaic virus (CaMV), the type species of the family, was ranked sixth in the world in a list of the most scientifically or economically important plant viruses. This notoriety is due purely to the major conceptual advances that have been made in plant virology using CaMV as a model pathogen. However, several relatively lesser known viruses in the family, such as Rice tungro bacilliform virus and Cacao swollen shoot virus , are very serious constraints to crop production in tropical regions of the world. In this article, information on the taxonomy, replication cycle, vector transmission, epidemiology and disease management of this important group of plant viruses is summarised. Key Concepts: The Caulimoviridae is the only family of plant viruses with a double‐stranded deoxyribonucleic acid (dsDNA) genome, and in common with all viral retroelements, incorporates a reverse transcription step in the replication cycle. Cauliflower mosaic virus is the type species of the family, and has been a very important model plant virus for elucidating fundamental aspects of virus replication, cell‐to‐cell movement and aphid transmission. Members of the Caulimoviridae are most prominent in tropical regions, where they cause serious diseases such as rice tungro, cacao swollen shoot and banana streak disease. The most important component of a control programme for these viruses is to reduced inoculum levels by using clean planting material, avoiding overlapping crops, and removing diseased plants and alternative hosts of the virus. In some host species, infection can arise as a consequence of activation of viral DNA that is integrated in the nuclear genome of the plant.

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Splicing of Cauliflower mosaic virus 35S RNA serves to downregulate a toxic gene product

Cited by 20 publications

References 34 publications

A Single Amino Acid Position in the Helper Component of Cauliflower Mosaic Virus Can Change the Spectrum of Transmitting Vector Species

A Single Amino Acid Position in the Helper Component of Cauliflower Mosaic Virus Can Change the Spectrum of Transmitting Vector Species

The Ribosomal Shunt Translation Strategy of Cauliflower Mosaic Virus Has Evolved from Ancient Long Terminal Repeats

Caulimoviridae (Plant Pararetroviruses)

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