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J L Lalanne

Publications and source records attributed to J L Lalanne.

15 recordsLinked to original sources
PubMed1997

Identification of five new genes, closely related to the interleukin-1beta converting enzyme gene, that do not encode functional proteases.

Interleukin-1beta converting enzyme (ICE) was the first identified member of a growing family of cysteine proteases that now includes ten mammalian homologs. Within this large family, two functional proteins, denoted TX and TY share 60% amino-acid identity with ICE in the mature protein and, together with ICE, constitute the ICE subfamily. The present study describes the identification of five new gene sequences, denoted S1-S5, closely related to ICE and TX and belonging to this subfamily. Sequences were identified using genomic Southern-blot analysis of human DNA with probes corresponding to ICE and TX exon 6. Using PCR amplification and cloning, the complete exon-6 sequence of these new genes was identified; three exhibit around 90% identity with Ice within exon 6, whereas the two others share about 70% identity with Ice. Examination of open reading frames and of amino acids essential for ICE activity indicate that none of these genes encodes for a functional protease. In conclusion, extensive analysis of the genes closely related to Ice shows that the Ice subfamily is constituted of eight members. Three of them encode for functional proteases (ICE, TX and TY) whereas the remaining members probably correspond to pseudogenes.

Amino Acid Sequence↗
PubMed1996

Identification of a cysteine protease closely related to interleukin-1 beta-converting enzyme.

The present study describes the identification and molecular cloning of a new member of the interleukin-1 beta-converting enzyme (ICE) family denoted transcript Y (TY). TY is very closely related to both ICE (51% amino acid identity) and a protein named transcript X (TX) (75% amino acid identity) that we recently identified [Faucheu, C., Diu, A., Chan, A.W.E., Blanchet, A.-M., Miossec, C., Hervé, F.,Collard-Dutilleul, V., Gu, Y., Aldape, R., Lippke, J., Rocher, C., Su, M.S.-S., Livingston, D.J., Hercend, T. & Lalanne, J.-L. (1995) EMBO J. 14, 1914-1922]. The amino acids that are implicated in both the ICE catalytic site and in the PI aspartate-binding pocket are conserved in TY. Within the ICE gene family, TY belongs to a subfamily of proteins closely related to the prototype ICE protein. Using transfection experiments into mammalian cells, we demonstrate that TY has protease activity on its own precursor and that this activity is dependent on the presence of a cysteine residue at position 245. However, despite the close similarity between TY and ICE active sites, TY fails to process the interleukin-1 beta precursor. In addition, as already observed for ICE and TX, TY is able to induce apoptosis when overexpressed in COS cells. TY therefore represents a new member of the growing family of apoptosis-inducing ICE-related cysteine proteases.

Amino Acid Sequence↗
PubMed1995

Cloning and characterization of the lipase operon from Mycoplasma mycoides subspecies mycoides LC.

Lipases, serine esterase enzymes, play an essential role in the mycoplasmal nutritional requirement for long-chain fatty acids. Although the lipase(s) activity in different mycoplasma species has been investigated, the molecular biology of the corresponding genes has not been studied. Using a single-primer PCR technique combined to more classical cloning systems, an operon containing three open reading frames (ORF), each of which could encode a lipase protein of 264, 264 or 269 amino acids (aa), was identified from Mycoplasma mycoides subsp. mycoides LC. Analysis of aa sequences of the encoded polypeptides showed that they display high aa similarity between each other (65-79%) and 28-31% identity to other prokaryotic lipases. Moreover, a lipase-esterase activity could be detected when the mycoplasmal lipase-encoding genes were expressed in a strong opal-suppressor-bearing Escherichia coli strain.

Amino Acid Sequence↗
PubMed1995

Interleukin-1 beta converting enzyme requires oligomerization for activity of processed forms in vivo.

Interleukin-1 beta converting enzyme (ICE) is composed of 10' (p10) and 20 kDa (p20) subunits, which are derived from a common 45 kDa precursor. Recent crystallographic studies have shown that ICE exists as a tetramer (p20/p10)2 in the crystal lattice. We provide evidence that the p10 and p20 subunits of ICE associate as oligomers in transfected COS cells. Using intragenic complementation, we show that the activity of a p10/p10 interface mutant defective in autoprocessing can be restored by co-expression with active site ICE mutants. Different active site mutants can also complement each other by oligomerization to form active ICE. These studies indicate that ICE precursor polypeptides may associate in different quaternary structures and that oligomerization is required for autoprocessing. Furthermore, integenic complementation of active site mutants of ICE and an ICE homolog restores autoprocessing activity, suggesting that hetero-oligomerization occurs between ICE homologs.

Amino Acid Sequence↗
PubMed1992

Purification and properties of a recombinant sulfur analog of murine selenium-glutathione peroxidase.

We previously constructed plasmids for synthesis of glutathione-peroxidase (GPx) mutants in an Escherichia coli expression system. In these recombinant proteins either cysteine ([Cys]GPx mutant) or serine ([Ser]GPx mutant) were present in place of the active-site selenocysteine (SeCys) of the natural enzyme. We have now investigated GPx activity of [Cys]GPx and [Ser]GPx mutants. Enzyme assays performed on preparations of these partially purified proteins demonstrated that the [Cys]GPx mutant exhibited a significant GPx activity, unlike the [Ser]GPx mutant. Purification of [Cys]GPx was performed in two steps of ion-exchange chromatography giving a 98% homogenous protein in 50% yield. The purified [Cys]GPx protein was shown to be a symmetrical tetramer by the means of gel-filtration HPLC and SDS/PAGE. Two isoelectric points were found (6.8 and 7.2) which may reflect two different oxidation states of the mutant protein. The GPx activity of the [Cys]GPx mutant was optimal at pH 8.5. The [Cys]GPx mutant had a specific activity approximately 1000-fold smaller than that of the natural enzyme, and was very easily inactivated by hydroperoxides. Inhibition of the activity with iodoacetate determined a pKa of 8.3, presumably that of the active-site cysteine. Unlike that of SeGPx, the GPx activity of [Cys]GPx was only slightly inhibited by mercaptosuccinate. We discuss hypothetical mechanistic constraints of either catalytic cycle, which may explain such results.

Animals↗
PubMed1991

Cloning of murine SeGpx cDNA and synthesis of mutated GPx proteins in Escherichia coli.

Glutathione peroxidase (GPx) of mammalian cells and Escherichia coli formate dehydrogenase both contain a selenocysteine (SeCys) in their amino acid (aa) sequence. In these two enzymes, this aa is encoded by a UGA codon, which is usually a stop codon for protein synthesis. We constructed plasmids to test the synthesis of GPx in E. coli. These constructions permitted high-level production of GPx mutants, where the SeCys codon was replaced by cysteine (UGC, UGU) or serine (UCA) codons, but synthesis of selenoprotein could not be detected: our data suggest that signals used for the recognition of the UGA codon as a SeCys codon are not conserved between E. coli and mammalian cells.

Animals↗
PubMed1985

Expression of class I genes in the major histocompatibility complex: identification of eight distinct mRNAs in DBA/2 mouse liver.

The mouse H-2 multigene family includes the genes coding for the major transplantation antigens and for genes located in the Qa-TIa region. We have studied a collection of class I cDNA clones made from liver mRNA of DBA/2 mice (H-2d haplotype) and found that at least six distinct class I genes are transcribed, including three genes of the Qa-TIa region. Two of these six genes each yield two distinct mRNAs, resulting from alternate splicing. Altogether, liver cells may express at least eight distinct class I polypeptides, of which three might be secreted, while one may be a new presumptive nonpolymorphic surface antigen.

Amino Acid Sequence↗
PubMed1984

Alternative splicing in the 5' moiety of the H-2Kd gene transcript.

The H-2Kd gene, which encodes a mouse major transplantation antigen, was transfected into L TK- mouse fibroblasts. Two transcripts of the gene were detected by S1 nuclease mapping analysis. They correspond to two previously characterized cDNA clones isolated from DBA/2 mouse liver RNA, leading to the conclusion that the H-2Kd gene gives rise to two distinct transcripts through an alternate use of splicing sites. The non-canonical RNA potentially encodes a so far undescribed H-2Kd-like molecule. It is present in all tissues tested (liver, spleen, thymus, kidney) albeit in lower amounts (approximately 10-fold less) than the canonical RNA coding for H-2Kd.

Animals↗
PubMed1983

Different exon-intron organization at the 5' part of a mouse class I gene is used to generate a novel H-2Kd-related mRNA.

A cDNA library constructed from liver mRNA of DBA/2 (H-2d) mice has been screened with H-2-specific probes. The nucleotide sequence of one clone (pH-2d-24) indicates that it derives from an H-2 gene with an unexpected exon-intron organization. Nucleotide sequence comparisons suggest that two distinct mRNAs are produced from a single H-2Kd gene by a mechanism involving the use of alternative splicing sites in its 5' region. pH-2d-24 carries an open reading frame encoding a thus-far-undescribed polypeptide product identical to an H-2Kd-molecule, except for the NH2-terminal half of the first domain.

Amino Acid Sequence↗
PubMed1982

Comparison of nucleotide sequences of mRNAs belonging to the mouse H-2 multigene family.

The complete nucleotide sequences of three cDNAs coding for the C-terminal part of mouse histocompatibility (H-2) antigens, and for the 3' non coding regions of these clones have been determined. Comparison of the sequence indicates a large homology throughout the coding and non-coding regions and suggests the existence of a genetic mechanism which homogenizes nucleotide sequences among genes of the H-2 multigene family.

Amino Acid Sequence↗
PubMed1975

[Migrating or ectopic teeth].

These three cases are examples of ectopia related to tumor formations which they may have precipitated or of which they are the consequence. Here it is not a question of explaining the phenomenon, but only of showing some cases of migration or of relatively exceptional ectopia with the specific pathways of approach.

Adolescent↗