Odile Hemmer

Learn More
Plants employ small RNA-mediated posttranscriptional gene silencing as a virus defense mechanism. In response, plant viruses encode proteins that can suppress RNA silencing, but the mode of action of most such proteins is poorly understood. Here, we show that the silencing suppressor protein P0 of two Arabidopsis-infecting poleroviruses interacts by means(More)
In plants, post-transcriptional gene silencing (PTGS) is part of a defence mechanism against virus infection. Several plant viruses have been shown to encode proteins which can counteract PTGS. In this paper it is demonstrated that P15 of peanut clump pecluvirus (PCV) has anti-PTGS activity. P15 is a small cysteine-rich protein with no sequence similarity(More)
The genome of peanut clump pecluvirus (PCV) consists of two messenger RNA components which contain, respectively, three and five open reading frames (ORFs). Inoculation of transcripts from full-length cDNA clones derived from the PCV RNAs showed that RNA-1 is able to replicate in the absence of RNA-2 in protoplasts, but both RNAs are necessary for plant(More)
Satellite RNA depend for their multiplication on the co-infection of a host cell by a helper virus which can itself multiply independently of the satellite. Four types of satellite RNA have been distinguished on the basis of the size of the RNA and what sort, if any, of protein they encode. One of them, the B-type, comprises relatively large RNA which are(More)
Synthetic transcripts of tomato black ring virus satellite RNA (TBRV satRNA), isolate L, were prepared from cDNA cloned in the Bluescribe transcription vector. Transcripts with 49 (T49L) or two (T2GL) extra nucleotides at their 5' ends and 42 extra nucleotides at their 3' ends were able to induce, but to different extents, the synthesis in vitro of the(More)
Translation of tomato black ring virus (TBRV) RNA-1 in a rabbit reticulocyte lysate leads to the synthesis of a 250K polyprotein which cleaves itself into smaller proteins of 50, 60, 120, and 190K. Polypeptides synthesized from synthetic transcripts corresponding to different regions of TBRV RNA-1 are processed only when they encode the 23K protein(More)
Tomato black ring virus isolate L supports the multiplication of a large satellite RNA of 1376 nt which has no common features with the two genomic RNAs except for the terminal motif 5' VPg UUGAAAA and a 3' poly(A) tail. The TBRV sat-RNA contains an ORF for a protein of 48K which is translated both in vitro and in vivo. To determine the function of the 48K(More)
RNA-1 of Peanut clump virus (PCV) encodes the proteins P131 and P191, containing the signature motifs of replication proteins, and P15, which regulates viral RNA accumulation. In PCV-infected protoplasts both P131 and P191 were immunodetected in the perinuclear region. Laser scanning confocal microscopy (LSCM) showed that P131 and P191 colocalized with(More)
The synthesis of proteins encoded by the RNA of tomato black ring virus (TBRV) in vivo was studied in protoplasts by direct labelling with [35S]methionine, and in protoplasts and plants by immunoblotting experiments with specific antisera. Comparison of the proteins synthesized in infected and mock-inoculated protoplasts suggested that proteins of M(r)(More)
Tomato black ring virus RNA-1 was translated in a rabbit reticulocyte lysate. The primary translation product of Mr 250K, which corresponds to its whole coding capacity, was synthesized within 45 min and, during further incubation in the translation medium, was proteolytically processed. Essentially, four cleavage products (P190, P120, P60 and P50) were(More)