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Biomedical subjects

J Laporte

Publications and source records attributed to J Laporte.

At least 127 records · Page 7Linked to original sources
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Sequence and analysis of BECV F15 matrix protein.

Clones from the bovine enteric coronavirus (F15) cDNA library were cloned in pBR322 and sequenced by the method of Sanger and Coulson. This led to the identification of a sequence of 1,300 bases which contained a single open reading frame of 690 bases yielding a protein having properties of the matrix protein (M). It was comprised of 230 amino acids with a molecular weight of 26,376 Da. It was hydrophobic and had a net charge of +8 at neutral pH. Analysis of its secondary structure could not establish a simple transmembrane arrangement of the amino acids. Comparison of its nucleotide sequence with that of BECV Mebus strain showed only a two-base change resulting in a 100% homology between the two amino acid sequences. Furthermore, a very conserved structure of M appeared on comparison with the Dayoff optimal alignment of MHV-A59, MHV-JHM, TGEV, IBV Beaudette and IBV 6/82M amino acid sequences. As the two strains of BECV, F15 and Mebus present some antigenic differences, this led us to reconsider the role of M in viral antigen specificity. A hypothesis is that, as it seems to possess the necessary information on its transmembrane region, it is an ideal candidate for the viral budding process.

Amino Acid Sequence↗
PubMedDate not supplied

Sequence and analysis of bovine enteritic coronavirus (F15) genome. I. Sequence of the gene coding for the nucleocapsid protein; analysis of the predicted protein.

Sequences encoding the N protein of the bovine enteritic coronavirus-F15 strain (BECV-F15) have been cloned in PBR322 plasmid using cDNA produced by priming with oligo-dT on purified viral genomic RNA. Some 265 insert-containing clones were studied. Hybridization of these inserts with poly(A)+ RNA extracted from infected cells led to the conclusion that they were located at the 3'-end of the genome. After subcloning in M13 phage DNA, clones were sequenced by the Sanger technique. A 1,710-nucleotide sequence corresponding to the gene coding for the viral N-protein was established. It shows 2 overlapping open reading frames (ORF). The 3'-non-coding end of the gene has an 8-nucleotide sequence in common with the homologous genome areas of MHV, TGE and IBV viruses. This sequence may represent the polymerase RNA binding site. An upstream sequence surrounding the first AUG of the smaller ORF corresponds to a potentially functional initiation codon. The sequence of the primary translation product deduced from the DNA sequence predicts a polypeptide of 207 amino acids (22.9 Kd) with a high leucine (19.8%) content, possessing a hydrophobic N-terminal end. The larger ORF has a coding capacity of 448 amino acids (49.4 Kd), corresponding to the N-protein molecular weight. The deduced protein possesses 43 serine residues (9.6% of the total amino acid content) which may be phosphorylated and involved in N-protein/RNA binding. N-protein also has 5 regions with a high basic amino acid content. One of them is also serine-rich and has a strong homology site with MHV, TGE and IBV viruses. In the first part of the N-terminal, a 12-amino-acid sequence (PRWYFYYLGTGP) is highly conserved for BECV-F15, JHM, TGE and IBV viruses. BCV Mebus strain and BECV-F15 have only minor differences in their N-protein sequence.

Amino Acid Sequence↗
PubMedDate not supplied

Genomic organization of the MTM1 gene implicated in X-linked myotubular myopathy.

X-linked recessive myotubular myopathy (XLMTM) is a very severe congenital muscular disease characterised by an impaired maturation of muscle fibres, and caused by defects in the MTM1 gene. This gene defines a new family of putative tyrosine phosphatases conserved through evolution. We have determined intronic flanking sequences for all the 15 exons to facilitate the detection of mutations in patients and genetic counselling. We characterised a new polymorphic marker in the immediate vicinity of the gene, which might prove useful for linkage analysis. Sequencing of the TATA-less predicted promoter provides the basis for transcriptional regulatory studies.

Base Sequence↗
PubMedDate not supplied

[Research on coronaviruses in water. I. Adsorption and elution of the coronavirus on glass powder].

The purpose of the research was to determine under what conditions enteric coronaviruses from water can be optimally concentrated by acid-pH adsorption on glass-powder followed by alkaline-pH elution. The 14C labelled bovine enteric coronavirus was grown on HRT18 cell monolayers and purified. Virus adsorption was studied in relation to pH: optimal adsorption yield--between 50 to 75% (mean value: 62%)--was obtained at pH less than or equal to 3.5. Elution was made comparatively with a 0.05 M glycine solution and a 3% beef extract solution. Virus elution occurred mostly at alkaline pH with a maximum yield between 38 and 55% for pH values between 9 and 11. Owing to the sensitivity of coronavirus to acid (pH 3) and alkaline pH (pH greater than or equal to 10), adsorption was optimal at pH 3.3 and elution at pH 9. Under such conditions, the overall efficiency of the method appears to stand between 24 and 28%.

Adsorption↗