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L Bougueleret

Publications and source records attributed to L Bougueleret.

31 records · Page 2Linked to original sources
PubMed1986

Relevance of the lariat model to the splicing of the H-2 gene family.

We examined the splicing of the H-2 gene family, taking the H-2Kd as a prototype, in the framework of the lariat model. We mainly investigated the mechanism described by Konarska et al. [Nature (Lond.) 313, 552-557 (1985)] who propose a direct interaction between the 5' splicing site and the branching region. We also checked each of the H-2 introns for the presence of patterns resembling the published consensus for the branching region. The known splicing events in the H-2 gene family are not always consistent with the current models, and our results indicate that slightly different mechanisms govern the splicing of different introns. A tentative explanation of the alternative splicing of the first and last intron, previously described, is given. The removal of the large third intron is not easily rationalized unless new rules for an additional multistep processing are postulated.

Animals↗
PubMed1986

Heuristic informational analysis of sequences.

Nucleotide or amino-acid sequences are interpreted as successions of words of length k (k-tuples) the frequencies of which are highly variable in different statistical populations of genes or proteins. After building k-tuple reference tables from coherent subsets or entire data banks, the local information content profile of individual sequences is drawn. Anomalous regions (peaks or depressions) of such a profile can lead to the discovery and identification of specific sequence patterns. Along the same principle, the simultaneous use of two reference statistical populations and the computation of an index combining the two information profiles lead to a general and powerful discriminant analysis methods. The identification of a "signal" associated with gene conversion, the introns/exons discrimination and the location of function specific patterns in proteins are given as examples of successful applications of this heuristic informational approach.

Amino Acid Sequence↗
PubMed1985

Overproduction of the EcoR V endonuclease and methylase.

Strains overproducing the EcoR V endonuclease and methylase have been obtained by inserting each of the two genes in expression vectors containing the lambda PL promoter. The methylase is overproduced to a level reaching 5-10% of the total cellular proteins, which represents a 50-100 fold increase. A 30 fold overproduction of endonuclease was achieved by randomly positioning the EndRV gene downstream of the lambda PL promoter. The situation in the endonuclease overproducing clone resembles that encountered in maxi-cells. The strains described here allowed a quick purification of both enzymes in sufficient amounts for crystallisation attempts.

Base Sequence↗
PubMed1985

Computer generation and statistical analysis of a data bank of protein sequences translated from GenBank.

We describe PGtrans, a new and freely available protein sequence databank (2625 sequences, 554198 amino-acids). This data bank is routinely produced by automatic computer translation of the nucleotide sequence library GenBank. The information needed for the translation process (transcriptional orientation, location of coding regions, splice sites and pertinent genetic code) is gathered by the translation program through an "intelligent" scanning of the documentary field of each GenBank entry. Inconsistencies resulting in unexpected termination codons are detected and reported thus allowing the correction of data bank errors. PGtrans is intended as a tool for protein similarity searches. Its reasonable overall size (2 Moctets) makes it suitable for micro-computer environments. Up to date amino-acid composition data and relative abundances of di-, tri-, and tetra-peptides in proteins of known sequences are presented and discussed.

Amino Acid Sequence↗
PubMed1984

Characterization of the genes coding for the Eco RV restriction and modification system of Escherichia coli.

A plasmid encoding the recently described Eco RV restriction and modification system has been isolated and characterized. This plasmid, pLB1 , is 6.2 kb long and carries only the Eco RV genes. A subclone of 3 kb has been inserted in pBR322. The relative positions of the endonuclease and the methylase genes were determined by the construction of a set of overlapping deletions generated by Bal31 resection. The DNA sequence of a 2.2 kb fragment containing the two genes was determined. The two genes are transcribed divergently from a 310 bp region and the assignment of the coding region has been confirmed by direct aminoacid sequence analysis. Possible mechanisms of regulation of the endonuclease gene expression at the translational level are proposed and discussed.

Amino Acid Sequence↗
PubMed1983

Cloning of several cDNA segments coding for human liver proteins.

A human cDNA library was constructed using M13 derivative vectors. The simple and rapid procedures for sequencing single-stranded DNA by the dideoxy chain termination method allowed a screening of individual clones directly by DNA sequence analysis. Some of these clones were identified as coding for: serum albumin, alpha1-antitrypsin, retinol-binding protein, prothrombin, haptoglobin, and metallothionein. Furthermore, a clone coding for aldolase B was tentatively identified on the basis of high sequence homology with rabbit muscle aldolase.

Amino Acid Sequence↗
PubMed1981

Conjugative R plasmids in group C and G streptococci.

Two streptococcal isolates of groups C and G harbored conjugative R plasmids with molecular weights of 17 X 10(6) (pIP646) and 20 X 10(6) (pIP920). These plasmids carried genetic markers for resistance to macrolides and related drugs, as well as to chloramphenicol (pIP920), and have very similar HindIII restriction enzyme patterns.

Conjugation, Genetic↗
PubMed1979

High-level, plasmid-borne resistance to gentamicin in Streptococcus faecalis subsp. zymogenes.

Each of three isolates of Streptococcus faecalis subsp. zymogenes harbored three R plasmids and a hemolysin-bacteriocin plasmid. The plasmids carried by one of these strains were physically characterized after their conjugative transfer. In each strain one of the plasmids carried genetic markers for resistance to gentamicin, kanamycin, sisomicin, netilmicin, and tobramycin.

Anti-Bacterial Agents↗
PubMedDate not supplied

Rare sequence motifs are common constituents of hypervariable antibody regions.

An analysis of the amino acid sequences of variable regions of human and mouse antibody molecules was performed. It involved comparison of their constituent tetrapeptides with those found in a reference set (the somatic self) built with non-immunological proteins found in a protein data base. It appeared that hypervariable regions, particularly CDR1 and CDR3, are often made up of rare tetrapeptides not present in the reference set. As assessed by simple statistical tests, this bias was significant. We discuss its possible connection with the problem of antibody immunogenicity. This result provides indirect support for the existence of idiopeptides predicted by the "peptidic self model".

Amino Acid Sequence↗
PubMedDate not supplied

Hepatitis B virus DNA integration in a sequence homologous to v-erb-A and steroid receptor genes in a hepatocellular carcinoma.

Hepatitis B virus (HBV) is clearly involved in the aetiology of human hepatocellular carcinoma (HCC) and the finding of HBV DNA integration into human liver DNA in almost all HCCs studied suggested that these integrated viral sequences may be involved in liver oncogenesis. Several HBV integrations in different HCCs and HCC-derived cell lines have been analysed after molecular cloning without revealing any obvious role for HBV. From a comparison of a HBV integration site present in a particular HCC with the corresponding unoccupied site in the non-tumorous tissue of the same liver, we now report that HBV integration places the viral sequence next to a liver cell sequence which bears a striking resemblance to both an oncogene (v-erb-A) and the supposed DNA-binding domain of the human glucocorticoid receptor and human oestrogen receptor genes. We suggest that this gene, usually silent or transcribed at a very low level in normal hepatocytes, becomes inappropriately expressed as a consequence of HBV integration, thus contributing to the cell transformation.

Amino Acid Sequence↗