Biomedical subjects

J M Mesnard

Publications and source records attributed to J M Mesnard.

24 records · Page 2Linked to original sources

PubMed1988

Cauliflower mosaic virus gene I product detected in a cell-wall-enriched fraction.

Gene I product of cauliflower mosaic virus was immunodetected in a cell-wall-enriched fraction from infected turnip leaves in addition to its detection in viroplasms and replication complexes. The immunoreaction was carried out with an antiserum raised against a 15 amino acid long synthetic peptide corresponding to the carboxy-terminus of potential gene I protein (P1). The presence of P1 in different subcellular fractions was investigated as a function of time during viral multiplication. At late infection times, P1 was found only in the cell-wall-enriched fraction.

Cell Wall↗

PubMed1988

Organization of RNA transcripts from a 7.8-kb region of the frog virus 3 genome.

The detailed organization of the RNAs transcribed from a region of the FV 3 genome (Sa/I-F fragment and adjacent sequences) has been determined. The information was derived from the cell-free translation of hybrid-selected RNA to locate the genes encoding specific polypeptides, RNA filter hybridization to size the transcripts, and S1 nuclease mapping to locate the 5'- and 3'-ends of the RNAs on the genome. Three genes are contiguous and are transcribed from the same strand: two immediate early genes encoding transcripts of about 1.3 kb that directed the in vitro synthesis of 42K and 46K polypeptides, separated by the late gene encoding the major capsid protein (48K). At an advanced stage in infection, transcripts derived from the immediate early genes are also present. A set of RNAs with different 5'-ends ranging from 1.7 to 0.58 kb is produced from the p46 gene region whereas RNAs, 0.98 and 0.6 kb in size, complementary to the 5'-end of the p42 message, are synthesized. This gene cluster is located between two genes transcribed in the opposite direction from the rightward-reading strand: a late gene whose message is 0.5 kb in size and encodes a 15K polypeptide and a gene transcribed at immediate early and late times of infection which encodes a protein of 70 kDa. The 5'-end of the late RNA maps downstream of the 5'-end of the early one, their sizes being 1.85 and 2 kb, respectively, but both of them can be translated in vitro into a 70K polypeptide. These observations suggest that transcription is not regulated by the organization of the genes; they suggest rather that specific DNA sequences are responsible for the promotion of immediate early and late transcriptions.

DNA, Viral↗

PubMed1986

Mapping of the gene coding for the major late structural polypeptide on the frog virus 3 genome.

The gene encoding the major capsid polypeptide (MCP 48) of frog virus 3 (FV 3) has been mapped on the viral DNA. Late FV 3 messenger RNA, hybrid-selected by the SalI-F fragment or a subset of these sequences, BamHI-L and -W fragments, directed the synthesis in vitro of a 48 000 mol. wt. (48K) polypeptide. This product was recognized by monospecific antibodies raised against the major capsid polypeptide. The RNA complementary to these DNA sequences was about 1350 nucleotides in size. This transcript, encoding MCP 48, was precisely located; S1 nuclease analysis indicated that its 5' end mapped at 1250 nucleotides to the right and its 3' end at 160 nucleotides to the left of the BamHI site at the junction between the BamHI-W and -L fragments.

Animals↗

PubMed1984

Expression of a putative plant viral gene in Escherichia coli.

A recombinant plasmid, pCB300, was constructed which carries a cauliflower mosaic virus (CaMV) DNA insert corresponding to nucleotides 1825-2280, including the coding sequence (1830-2219) of open reading frame III (ORF III). This CaMV DNA insert was fused with the amino-terminal portion of the beta-galactosidase gene. Transcription of the hybrid gene is controlled by the lac promoter, which is repressed in Escherichia coli strain JM103 and can be induced by isopropylthio-beta-D-galactoside (IPTG). When the promoter is derepressed, cells harboring the chimeric plasmid produce an Mr 16 000 fusion protein. This protein is immunodetected by antibodies raised against an amino terminal synthetic peptide of 19 amino acids corresponding to a sequence predicted from the nucleotide sequence of ORF III.

Cloning, Molecular↗

PubMedDate not supplied

Expression of cauliflower mosaic virus gene I in Saccharomyces cerevisiae.

Cauliflower mosaic virus (CaMV) gene I encodes a 40-kDa protein, P1, which is thought to be involved in the cell-to-cell movement of the virus. In order to investigate its functioning, P1 was expressed in Saccharomyces cerevisiae transformed by an expression vector containing CaMV gene I. When produced in yeast, PI was 40 kDa in size and not N-glycosylated.

Blotting, Western↗

PubMedDate not supplied

Processing of the minor capsid protein of the cauliflower mosaic virus requires a cysteine proteinase.

The major capsid protein of the cauliflower mosaic virus (CaMV) is processed in vivo. The viral aspartic proteinase that catalyses this maturation has been characterized previously and is coded by the CaMV gene V. This virus has a second capsid protein, a minor component, encoded by gene III. This protein, P3, is also processed at its C-terminus in vivo. To determine whether P3 is matured by the CaMV proteinase P5, we expressed, in Saccharomyces cerevisiae, P3, P5 and a fusion protein P7-P4, containing potential sites of cleavage. P5 was found to be involved in maturation of P7-P4 but did not cleave P3. The latter result was confirmed by experiments carried out with an in vitro translation system (the reticulocyte lysate) and with preparations of replication complexes purified from infected plants. Moreover, [N-(L-3-trans-carboxyoxiran-2-carbonyl)-L-leu cyl]-amido(4-guanido)butane, a specific inhibitor of cysteine proteinases, inhibited the maturation of P3, suggesting that the two CaMV capsid proteins are not processed by the same proteolytic event.

Capsid↗