Biomedical subjects

D Portetelle

Publications and source records attributed to D Portetelle.

At least 55 records · Page 3Linked to original sources

PubMed1995

Sequence analysis of a 44 kb DNA fragment of yeast chromosome XV including the Tyl-H3 retrotransposon, the suf1(+) frameshift suppressor gene for tRNA-Gly, the yeast transfer RNA-Thr-1a and a delta element.

We have sequenced on both strands a 44,019 bp fragment located on the left arm of Saccharomyces cerevisiae chromosome XV. The sequenced segment contains 22 open reading frames (ORFs) of at least 100 amino acids long, one of which probably contains an intron. Six of the 22 ORFs correspond to known proteins: the multicopy suppressor of Snf1 protein 1, the two Tyl-H3 transposon proteins TyA and TyB, the myo-inositol transporter 2, the transcription factor protein Ino4 and the 3,4-dihydroxy-5-hexaprenylbenzoate methyltransferase. Of the 16 remaining ORFs, two show highest homologies with the yeast serine/threonine protein kinase Ste20 and the human tryptophanyl-tRNA synthetase. Eight ORFs show slight similarities with protein sequences described in data banks. DNA sequence comparison reveals also the presence of three known sequences: the Tyl-H3 transposable element, the yeast suf1(+) frameshift suppressor gene for tRNA-Gly and the yeast transfer RNA-Thr-1a. A fourth DNA sequence shows striking identities with the yeast delta elements.

Amino Acid Sequence↗

PubMed1995

Sequence of a 17.1 kb DNA fragment from chromosome X of Saccharomyces cerevisiae includes the mitochondrial ribosomal protein L8.

We have sequenced a continuous segment of 17,137 bp on chromosome X. Sequence analysis of this stretch revealed 14 open reading frames (ORFs) at least 100 amino acids long. One gene, encoding the mitochondrial 60S ribosomal protein L8, had already been sequenced. Four ORF products show weak homologies with known protein sequences. The nine remaining ORF products have no homologies with sequences in data banks.

Carboxylesterase↗

PubMed1995

The sequence of an 11.1 kb DNA fragment between ADH4 and ADE5 on the left arm of chromosome VII reveals the presence of eight open reading frames.

The complete sequence of a 11, 132 bp segment located on the left arm of chromosome VII of Saccharomyces cerevisiae has been determined and analysed. Eight open reading frames (ORFs) of at least 100 amino acids were identified. Five show similarities to known amino acid sequences. Another ORF encoding the chromosome segregation protein CSE1 is not entirely located in our sequenced fragment and is incomplete at its C-terminus. The two remaining ORFs do not display similarities to known sequences.

Adenosine Deaminase↗

PubMed1995

The YXXL signalling motifs of the bovine leukemia virus transmembrane protein are required for in vivo infection and maintenance of high viral loads.

The bovine leukemia virus (BLV) transmembrane protein (gp30) contains three YXXL motifs at its carboxyterminal end. Two of these motifs have been implicated in vitro in signal transduction pathways from the external to the intracellular compartment. In order to analyze the biological relevance of these motifs in vivo, recombinant BLV proviruses were constructed. A mutation of the tyrosine residue of the second YXXL motif completely destroyed the infectious potential of the virus in sheep. In contrast, the tyrosine of the first motif appeared to be dispensable for infectivity. However, the propagation of the recombinant virus within the animal was greatly impaired (as demonstrated by PCR and enzyme-linked immunosorbent assay). These recombinant BLVs thus exhibit an attenuated phenotype. Altogether, our data demonstrate the importance of the YXXL motifs of the BLV transmembrane protein for in vivo infection and viral propagation.

Animals↗

PubMed1994

Attenuation of bovine leukemia virus by deletion of R3 and G4 open reading frames.

Complex oncoviruses contain, in addition to the classical retroviral genes (gag, pol, and env), a region (X) located between the envelope sequences and the 3' long terminal repeat. The X region contains two genes, tax and rex, whose protein products are involved in transcriptional and posttranscriptional regulation of viral expression. In addition to these activators, the bovine leukemia virus (BLV) and the human T-cell leukemia virus (HTLV) contain alternative open reading frames (R3 and G4 for BLV; p30, p13, and p12 for HTLV). As a virus/animal model for HTLV-induced leukemogenesis, BLV provirus can be injected intradermally into sheep, where it induced B-lymphocyte transformation. Deletion of the R3 and G4 sequences from an infectious and tumorigenic BLV provirus greatly impaired the in vivo propagation of the viruses as demonstrated by DNA polymerase chain reaction, RNA blots, structural-protein ELISA, and immunofluorescence analysis. Our results show that the alternative open reading frames are required for maintaining high virus loads during the course of persistent infection in vivo. Thus, R3 and G4 are candidates for antiviral drug development. Furthermore, viruses with a deletion in these sequences should be tested as live attenuated vaccines.

Animals↗

PubMed1994

Complete DNA sequence of yeast chromosome XI.

The complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome XI has been determined. In addition to a compact arrangement of potential protein coding sequences, the 666,448-base-pair sequence has revealed general chromosome patterns; in particular, alternating regional variations in average base composition correlate with variations in local gene density along the chromosome. Significant discrepancies with the previously published genetic map demonstrate the need for using independent physical mapping criteria.

Base Sequence↗

PubMed1994

Identification of functional sites on bovine leukemia virus envelope glycoproteins using structural and immunological data.

Sequence analysis using the sensitive hydrophobic cluster analysis method shows that the bovine leukemia virus envelope glycoproteins conserve the general organization of the influenza hemagglutinin into a 'stem', containing the external part of the transmembrane glycoprotein and the N-terminal and C-terminal parts of the external glycoprotein, and a 'head', containing only external glycoprotein residues. However, our analysis suggests, for the first time, that the bovine leukemia virus envelope head will not adopt the typical 'jelly-roll' fold of the influenza A hemagglutinin head, but most likely folds into another type of 'Greek-key' structure corresponding to the overall topology of constant immunoglobulin domains. We constructed a three-dimensional model for the bovine leukemia virus envelope head by homology modeling using the crystal structure of the human histocompatibility antigen HLA-A2 alpha 3 domain. Furthermore, we propose a general model for the oligomeric organization of this head, based on the hemagglutinin trimer. The proposed structural organization of bovine leukemia virus external glycoprotein is further supported by antipeptide and monoclonal antibody reactivities. Our modeling study suggests that the loops of the two neutralizing peptides located in the head are adjacent at the top of the domain and define a potential interaction site of the external glycoprotein with its cellular receptor. This site is topologically similar to the binding site of hemagglutinin with its cellular receptor, sialic acid. The other neutralizing peptides are located within a small domain linking the head to the stem. These data are of interest for defining other oncoviral glycoproteins heads and receptor-binding sites.

Amino Acid Sequence↗

PubMed1994

Structural similarities between chaperone molecules of the HSP60 and HSP70 families deduced from hydrophobic cluster analysis.

In this study, the conservation of strong structural landmarks between all the members of two chaperone families (HSP60 and HSP70) was deduced from their sequences by hydrophobic cluster analysis. On this basis, we propose that the ATP-binding environment is maintained by a similar fold in both protein families. The observed similarities extend throughout the proteins, including both the ATPase domain and the C-terminal substrate-binding domain.

Adenosine Triphosphatases↗

PubMed1994

Sequencing and analysis of a 20.5 kb DNA segment located on the left arm of yeast chromosome XI.

A 20.5 kb DNA fragment from the left arm of chromosome XI of Saccharomyces cerevisiae has been sequenced and analysed. Thirteen open reading frames (ORFs) for proteins longer than 100 amino acids were discovered. Among them, two are the known genes MRP49 and TPK3; two others encode proteins which show strong similarity with a yeast putative protein kinase and a yeast choline transport protein; one other shows weaker similarity with a yeast Ca2+/calmodulin-dependent protein kinase. Moreover, two putative proteins encoded by ORFs located in the sequenced fragment are closely similar to non-yeast proteins: the Caenorhabditis elegans elongation factor 2 and a glutamic acid-rich protein of Plasmodium falciparum.

Base Sequence↗

PubMed1994

DNA sequencing of a 36.2 kb fragment located between the FAS1 and LAP loci of chromosome XI of Saccharomyces cerevisiae.

We have completely sequenced on both strands a continuous DNA segment of 36.2 kb located on the left arm of Saccharomyces cerevisiae chromosome XI. Sequence analysis reveals the presence of 20 open reading frames (ORFs) at least 100 amino acids long. Five of these ORFs correspond to known genes; five others show homology with known proteins; the ten remaining ORFs identified show no detectable homology with other protein sequences contained in data banks and may represent new biological functions.

Amino Acid Sequence↗

PubMed1994

Sequence analysis of a 40.2 kb DNA fragment located near the left telomere of yeast chromosome X.

We have sequenced on both strands a 40,257 bp fragment located near the left telomere of chromosome X of Saccharomyces cerevisiae. The sequenced segment contains 21 open reading frames (ORFs) at least 100 amino acids long. Five of the ORFs correspond to known amino acid sequences: two hypothetical proteins in the subtelomeric Y' repeat region of 65.4 and 12.8 KDa, the cytochrome B pre-mRNA processing CBP1 protein, the mitochondrial nuclease NUC1 and the CRT1 protein. Of the 16 remaining ORFs, eight show highest homologies with the S. cerevisiae hexose transporters family (two ORFs), the yeast alpha-glucosidase (two ORFs), the yeast PEP1 precursor, the Escherichia coli galactoside O-acetyltransferase, the S. cerevisiae 137.7 KDa protein located in the Y' region and a protein of unknown function of Schizosaccharomyces pombe. Finally, eight of the ORFs exhibit no significant similarity with any amino acid sequences described in data banks. DNA sequence comparison has revealed the presence of different repeated elements characteristic of yeast chromosome ends. Disruption studies have been performed on two ORFs encoding putative proteins of unknown function.

Base Sequence↗

PubMed1994

Common prevalence of alanine and glycine in mobile reactive centre loops of serpins and viral fusion peptides: do prions possess a fusion peptide?

Serpin reactive centre loops and fusion peptides released by proteolytic cleavage are particularly mobile. Their amino acid compositions reveal a common and unusual abundance of alanine, accompanied by high levels of glycine. These two small residues, which are not simultaneously abundant in stable helices (standard or transmembrane), probably play an important role in mobility. Threonine and valine (also relatively small amino acids) are also abundant in these two kinds of peptides. Moreover, the known 3D structures of an uncleaved serpin reactive centre and a fusion peptide are strikingly similar. Such sequences possess many small residues and are found in several signal peptides and in PrP, a protein associated with spongiform encephalopathies and resembling virus envelope proteins. These properties may be related to the infection mechanisms of these diseases.

Alanine↗

PubMed1994

Expression of intron-encoded maturase-like polypeptides in potato chloroplasts.

The trnK gene has been identified on a cloned plastid DNA fragment of potato (Solanum tuberosum cv Désirée). This gene codes for a tRNA-Lys and is interrupted by a 2.5-kb intron belonging to the group II organellar introns. In addition, this intervening sequence contains a long open reading frame potentially coding for a 509 amino-acid polypeptide (ORF509) related to mitochondrial intron-encoded maturases from fungi. The translational capacity of the trnK intron was first demonstrated in vitro in a prokaryotic DNA-directed expression system. In order to examine the expression of the intron in the potato plant, a synthetic peptide corresponding to the last nine amino acids of the predicted ORF509 product was used to raise antibodies. Western-blot experiments on chloroplast protein extracts, using a sensitive chemiluminescent detection system, identified polypeptides similar to in-vitro products. These results suggest that the trnK intron is expressed at the protein level in the plant. This is the first report of the in-vivo expression of an intron-encoded polypeptide in higher plant plastids.

Amino Acid Sequence↗

PubMed1994

Isolation of the missing 5'-end of the encoding region of the bovine leukemia virus cell receptor gene.

The missing 5'-end of the encoding region of the bovine leukemia virus (BLV) cell receptor gene (BLVRcp1/5') was isolated from a lambda gt11 cDNA library using the 32P-labeled EcoRI-SamI fragment corresponding to the 5'-end of a 2.3 kbp cDNA fragment encoding the binding domain of the bovine leukemia virus cell receptor gene (BLVRcp1). The nucleotide and amino acid sequence analysis of the BLVRcp1/5' cDNA revealed that the 1058 bp EcoRI fragment at its 5'-end contained a new 114 amino acid long sequence, and at its 3'-end contained a completely identical 88 amino acid overlapping region with the 5'-end of the BLVRcp1 cDNA. The combined sequences of both cDNAs represent the whole encoding region of the BLV cell receptor gene. The longest open reading frame of the BLV cell receptor gene encodes a protein containing 843 amino acids with a calculated molecular mass of 94.2 kDa which concurs with experimentally detected native BLV receptor protein. Search for homology has shown that about 250 bp of the BLV cell receptor gene is highly homologous to Venter's tag sequences of an unidentified gene from the human brain library.

Amino Acid Sequence↗

PubMed1994

The bovine leukemia virus (BLV) envelope glycoprotein gp51 as a general model for the design of a subunit vaccine against retroviral infection: mapping of functional sites through immunological and structural data.

Further advances in retroviral vaccine development require a better understanding of the antigenic structure of the envelope complex which is directly involved in infectivity events such as receptor recognition and membrane fusion. To design an optimal vaccine against BLV infection, we chose an approach based on the use of synthetic peptides covering 78% of the gp51 sequence in order to select only those segments that could induce a protective response via cellular and humoral immunity. On the other hand, we built a model of the BLV env glycoprotein 3D organization, based upon the very sensitive hydrophobic cluster analysis (HCA). The major information highlighted from this model is that the two loops, against which the most efficient neutralizing antipeptides antibodies are directed against, are in close proximity at the top of the "head" and could represent a potential site for receptor binding. These two peptides are of particular interest since they induce also a helper T-cell response. We further propose that the BLV envelope glycoprotein oligomerizes as a trimer.

Amino Acid Sequence↗

PubMed1994

TaqI restriction fragment length polymorphisms for growth hormone in bovine breeds and their association with quantitative traits.

The objectives of the present study were (1) to reveal GH-TaqI RFLPs in different bovine breeds and (2) to look for association between quantitative traits and GH-TaqI RFLPs in bulls highly selected for growth and meat production. Blood was sampled from 269 Holstein heifers, 48 Italian and 45 Hungarian Simmental heifers, 30 Normande heifers and 41 bulls and 13 heifers of the double-muscled Belgian White Blue breed. Bulls were weighed from 7 until 13 months of age and the average daily gain, the feed efficiency, the height and the phenotypic index were determined at the end of the experiment. GH-TaqI RFLPs revealed 4 DNA fragments of 6 (A), 5.2 (B), 4.4 (C) and 4.2 (D) kbp. The distribution of genotypes was different between Normande and the other breeds (P < 0.001) and between Belgian White Blue and Holstein (P < 0.001) or Hungarian Simmental breed (P < 0.005). The Normande heifers were also characterized by a high frequency of the AB genotype (53%) compared with other experimental breeds (range values: 7-24%). In the statistical analysis of the relationships between quantitative traits and GH-TaqI RFLPs in double-muscled Belgian White Blue bulls, the AC genotypic class was not used because of its low distribution. The AA class showed greater records of weight at 7 (P < 0.07) and 13 (P < 0.06) months of age than the AB class. In conclusion, this study has shown a correlation between the GH-TaqI RFLPs and weight at 7 and 13 months of age in Belgian White Blue bulls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Redox mechanism for the chaperone activity of heat shock proteins HSPs 60, 70 and 90 as suggested by hydrophobic cluster analysis: hypothesis.

We have recently shown that the N-terminal ATPase fragment of hsp70 (1-375, composed of domains I and II) as well as the subsequent domain III (376-520) may share three-dimensional similarities with hsp60. In this study, we propose that domain III, common to the hsp60s and hsp70s is also found in the hsp90s and adopts a beta-alpha-beta Rossmann-folded structure which is encountered in the NAD-binding domain of dehydrogenases. Consequently, with the help of the domain IV (in hsp70s and hsp90s) or of hsp10/GroES (in hsp60s) and possibly that of auxilliary partners, the hsp molecules could act as "unfoldases" or "reset systems" by disrupting secondary structures through redox reactions on the main polypeptidic chain with which they interact. The models built on this hypothesis may open up a new way for understanding the chaperone functions within the folding/unfolding processes.

Chaperonin 60↗

PubMed1994

Cloning and characterization of MN, a human tumor-associated protein with a domain homologous to carbonic anhydrase and a putative helix-loop-helix DNA binding segment.

MN is a transmembrane glycoprotein that has been detected in HeLa cells and in some human carcinomas. The expression of MN protein in HeLa cells is regulated by cell density. In HeLa x fibroblast cell hybrids its expression correlates with tumorigenicity. Using a specific monoclonal antibody we have identified a cDNA clone coding for MN. Analysis of the deduced amino acid sequence revealed strong structural homology between the central region of the MN protein and carbonic anhydrases (CA). MN sequence retains the conserved zinc-binding site as well as the enzyme's active center. In accord with these findings, MN protein from HeLa cells was found to bind zinc and to have carbonic anhydrase activity. The N-terminal region of MN shares some similarity with DNA binding proteins of the helix-loop-helix (HLH) family, and the protein was found to have affinity for DNA by DNA-cellulose chromatography. The region between the CA-like domain and the putative HLH domain is rich in imperfect repeats of serine, proline, glycine and acidic residues with few hydrophobic amino acids, resembling thus an activation region of transcription factors. The fact that MN protein is detectable in several types of human carcinomas, but not in corresponding non-cancerous tissues, suggests its possible role in neoplasia. In addition, the analysis of biological consequences of MN expression of NIH3T3 cells provides the evidence in favour of MN protein involvement in control of cell proliferation and transformation.

3T3 Cells↗