H. Brule - Academia.edu (original) (raw)

Papers by H. Brule

Research paper thumbnail of Search for characteristic structural features of mammalian mitochondrial tRNAs

Research paper thumbnail of Effect of a mutation in the anticodon of human mitochondrial tRNAPro on its post-transcriptional modification pattern

Nucleic Acids Research, 1998

Research paper thumbnail of Isoleucylation properties of native human mitochondrial tRNAIle and tRNAIle transcripts. Implications for cardiomyopathy-related point mutations (4269, 4317) in the tRNAIle gene

Human Molecular Genetics, 1998

A growing number of mutated mitochondrial tRNA genes have been found associated with severe human... more A growing number of mutated mitochondrial tRNA genes have been found associated with severe human diseases. To investigate the potential interference of such mutations with the primordial function of tRNAs, i.e. their aminoacylation by cognate aminoacyl-tRNA synthetases, a human mitochondrial in vitro aminoacylation system specific for isoleucine has been established. Both native tRNA Ile and isoleucyl-tRNA synthetase activity have been recovered from human placental mitochondria and the kinetic parameters of tRNA aminoacylation determined. The effect of pathological point mutations present in the mitochondrial gene encoding tRNA Ile has been tackled by investigating the isoleucylation properties of wild-type and mutated in vitro transcripts. Data show that: (i) modified nucleotides contribute to efficient isoleucylation; (ii) point mutation A4269G in the gene (A→G at nt 7 in the tRNA), associated with a cardiomyopathy, does not affect aminoacylation significantly; (iii) point mutation A4317G (A→G at nt 59 in the tRNA), reported in a case of fatal infantile cardiomyopathy, induces a small but significant decrease in isoleucylation. The potential implications of these findings on the understanding of the molecular mechanisms involved in the expression of pathology are discussed.

Research paper thumbnail of Dosage de la folate binding protein urinaire: mise au point et évaluation en cas de néphropathie

Nous avons mis au point une methode de dosage de la folate binding protein urinaire par etude de ... more Nous avons mis au point une methode de dosage de la folate binding protein urinaire par etude de sa liaison avec l'acide folique marque au tritium. L'analyse de la liaison par methode de Scatchard montre une affinite elevee (Ka = 5 a 20 nM −1 ). L'excretion urinaire varie entre 630 et 1230 pmoles/j chez des sujets temoins. Elle est augmentee dans 6 sur 13 cas de nephropathie tubulaire (valeurs extremes 436-4330 pmoles/j) et 4 sur 15 cas de nepropathie glomerulaire (valeurs extremes 4002 580 pmoles/j). La valeur etiologique de cette augmentation reste a determiner, ainsi que l'etude de la FBP urinaire dans l'etude du statut en folates

Research paper thumbnail of Search for characteristic structural features of mammalian mitochondrial tRNAs

Research paper thumbnail of The presence of modified nucleotides is required for cloverleaf folding of a human mitochondrial tRNA

Nucleic Acids Research, 1998

Direct sequencing of human mitochondrial tRNA Lys shows the absence of editing and the occurrence... more Direct sequencing of human mitochondrial tRNA Lys shows the absence of editing and the occurrence of six modified nucleotides (m 1 A9, m 2 G10, Ψ27, Ψ28 and hypermodified nucleotides at positions U34 and A37). This tRNA folds into the expected cloverleaf, as confirmed by structural probing with nucleases. The solution structure of the corresponding in vitro transcript unexpectedly does not fold into a cloverleaf but into an extended bulged hairpin. This non-canonical fold, established according to the reactivity to a large set of chemical and enzymatic probes, includes a 10 bp aminoacyl acceptor stem (the canonical 7 bp and 3 new pairs between residues 8-10 and 65-63), a 13 nt large loop and an anticodon-like domain. It is concluded that modified nucleotides have a predominant role in canonical folding of human mitochondrial tRNA Lys . Phylogenetic comparisons as well as structural probing of selected in vitro transcribed variants argue in favor of a major contribution of m 1 A9 in this process.

Research paper thumbnail of Effect of a mutation in the anticodon of human mitochondrial tRNAPro on its post-transcriptional modification pattern

Nucleic Acids Research, 1998

Although the gene sequences of all 22 tRNAs encoded in the human mitochondrial genome are known, ... more Although the gene sequences of all 22 tRNAs encoded in the human mitochondrial genome are known, little information exists about their sequences at the RNA level. This becomes a crucial limitation when searching for a molecular understanding of the growing number of maternally inherited human diseases correlated with point mutations in tRNA genes. Here we describe the sequence of human mt-tRNA Pro purified from placenta. It shows absence of editing events in this tRNA and highlights the presence of eight post-transcriptional modifications. These include T54, never found so far in an animal mt-tRNA, and m 1 G37, a modification known to have fundamental functional properties in a number of canonical tRNAs. Occurrence of m 1 G37 was further investigated in an analysis of the substrate properties of in vitro transcripts of human mt-tRNA Pro towards pure Escherichia coli methylguanosine transferase. This enzyme properly methylates G37 in mt-tRNA and is sensitive to the presence of a second G at position 36, neighboring the target nucleotide for methylation. Since mutation of nt 36 was shown to be correlated with myopathy, the potential consequences of nonmodification or under-modification of mt-tRNA nucleotides in expression of the particular myopathy and of mitochondrial diseases in general are discussed.

Research paper thumbnail of Isoleucylation properties of native human mitochondrial tRNAIle and tRNAIle transcripts. Implications for cardiomyopathy-related point mutations (4269, 4317) in the tRNAIle gene

Human Molecular Genetics, 1998

A growing number of mutated mitochondrial tRNA genes have been found associated with severe human... more A growing number of mutated mitochondrial tRNA genes have been found associated with severe human diseases. To investigate the potential interference of such mutations with the primordial function of tRNAs, i.e. their aminoacylation by cognate aminoacyl-tRNA synthetases, a human mitochondrial in vitro aminoacylation system specific for isoleucine has been established. Both native tRNA Ile and isoleucyl-tRNA synthetase activity have been recovered from human placental mitochondria and the kinetic parameters of tRNA aminoacylation determined. The effect of pathological point mutations present in the mitochondrial gene encoding tRNA Ile has been tackled by investigating the isoleucylation properties of wild-type and mutated in vitro transcripts. Data show that: (i) modified nucleotides contribute to efficient isoleucylation; (ii) point mutation A4269G in the gene (A→G at nt 7 in the tRNA), associated with a cardiomyopathy, does not affect aminoacylation significantly; (iii) point mutation A4317G (A→G at nt 59 in the tRNA), reported in a case of fatal infantile cardiomyopathy, induces a small but significant decrease in isoleucylation. The potential implications of these findings on the understanding of the molecular mechanisms involved in the expression of pathology are discussed.

Research paper thumbnail of Search for characteristic structural features of mammalian mitochondrial tRNAs

Research paper thumbnail of Effect of a mutation in the anticodon of human mitochondrial tRNAPro on its post-transcriptional modification pattern

Nucleic Acids Research, 1998

Research paper thumbnail of Isoleucylation properties of native human mitochondrial tRNAIle and tRNAIle transcripts. Implications for cardiomyopathy-related point mutations (4269, 4317) in the tRNAIle gene

Human Molecular Genetics, 1998

A growing number of mutated mitochondrial tRNA genes have been found associated with severe human... more A growing number of mutated mitochondrial tRNA genes have been found associated with severe human diseases. To investigate the potential interference of such mutations with the primordial function of tRNAs, i.e. their aminoacylation by cognate aminoacyl-tRNA synthetases, a human mitochondrial in vitro aminoacylation system specific for isoleucine has been established. Both native tRNA Ile and isoleucyl-tRNA synthetase activity have been recovered from human placental mitochondria and the kinetic parameters of tRNA aminoacylation determined. The effect of pathological point mutations present in the mitochondrial gene encoding tRNA Ile has been tackled by investigating the isoleucylation properties of wild-type and mutated in vitro transcripts. Data show that: (i) modified nucleotides contribute to efficient isoleucylation; (ii) point mutation A4269G in the gene (A→G at nt 7 in the tRNA), associated with a cardiomyopathy, does not affect aminoacylation significantly; (iii) point mutation A4317G (A→G at nt 59 in the tRNA), reported in a case of fatal infantile cardiomyopathy, induces a small but significant decrease in isoleucylation. The potential implications of these findings on the understanding of the molecular mechanisms involved in the expression of pathology are discussed.

Research paper thumbnail of Dosage de la folate binding protein urinaire: mise au point et évaluation en cas de néphropathie

Nous avons mis au point une methode de dosage de la folate binding protein urinaire par etude de ... more Nous avons mis au point une methode de dosage de la folate binding protein urinaire par etude de sa liaison avec l'acide folique marque au tritium. L'analyse de la liaison par methode de Scatchard montre une affinite elevee (Ka = 5 a 20 nM −1 ). L'excretion urinaire varie entre 630 et 1230 pmoles/j chez des sujets temoins. Elle est augmentee dans 6 sur 13 cas de nephropathie tubulaire (valeurs extremes 436-4330 pmoles/j) et 4 sur 15 cas de nepropathie glomerulaire (valeurs extremes 4002 580 pmoles/j). La valeur etiologique de cette augmentation reste a determiner, ainsi que l'etude de la FBP urinaire dans l'etude du statut en folates

Research paper thumbnail of Search for characteristic structural features of mammalian mitochondrial tRNAs

Research paper thumbnail of The presence of modified nucleotides is required for cloverleaf folding of a human mitochondrial tRNA

Nucleic Acids Research, 1998

Direct sequencing of human mitochondrial tRNA Lys shows the absence of editing and the occurrence... more Direct sequencing of human mitochondrial tRNA Lys shows the absence of editing and the occurrence of six modified nucleotides (m 1 A9, m 2 G10, Ψ27, Ψ28 and hypermodified nucleotides at positions U34 and A37). This tRNA folds into the expected cloverleaf, as confirmed by structural probing with nucleases. The solution structure of the corresponding in vitro transcript unexpectedly does not fold into a cloverleaf but into an extended bulged hairpin. This non-canonical fold, established according to the reactivity to a large set of chemical and enzymatic probes, includes a 10 bp aminoacyl acceptor stem (the canonical 7 bp and 3 new pairs between residues 8-10 and 65-63), a 13 nt large loop and an anticodon-like domain. It is concluded that modified nucleotides have a predominant role in canonical folding of human mitochondrial tRNA Lys . Phylogenetic comparisons as well as structural probing of selected in vitro transcribed variants argue in favor of a major contribution of m 1 A9 in this process.

Research paper thumbnail of Effect of a mutation in the anticodon of human mitochondrial tRNAPro on its post-transcriptional modification pattern

Nucleic Acids Research, 1998

Although the gene sequences of all 22 tRNAs encoded in the human mitochondrial genome are known, ... more Although the gene sequences of all 22 tRNAs encoded in the human mitochondrial genome are known, little information exists about their sequences at the RNA level. This becomes a crucial limitation when searching for a molecular understanding of the growing number of maternally inherited human diseases correlated with point mutations in tRNA genes. Here we describe the sequence of human mt-tRNA Pro purified from placenta. It shows absence of editing events in this tRNA and highlights the presence of eight post-transcriptional modifications. These include T54, never found so far in an animal mt-tRNA, and m 1 G37, a modification known to have fundamental functional properties in a number of canonical tRNAs. Occurrence of m 1 G37 was further investigated in an analysis of the substrate properties of in vitro transcripts of human mt-tRNA Pro towards pure Escherichia coli methylguanosine transferase. This enzyme properly methylates G37 in mt-tRNA and is sensitive to the presence of a second G at position 36, neighboring the target nucleotide for methylation. Since mutation of nt 36 was shown to be correlated with myopathy, the potential consequences of nonmodification or under-modification of mt-tRNA nucleotides in expression of the particular myopathy and of mitochondrial diseases in general are discussed.

Research paper thumbnail of Isoleucylation properties of native human mitochondrial tRNAIle and tRNAIle transcripts. Implications for cardiomyopathy-related point mutations (4269, 4317) in the tRNAIle gene

Human Molecular Genetics, 1998

A growing number of mutated mitochondrial tRNA genes have been found associated with severe human... more A growing number of mutated mitochondrial tRNA genes have been found associated with severe human diseases. To investigate the potential interference of such mutations with the primordial function of tRNAs, i.e. their aminoacylation by cognate aminoacyl-tRNA synthetases, a human mitochondrial in vitro aminoacylation system specific for isoleucine has been established. Both native tRNA Ile and isoleucyl-tRNA synthetase activity have been recovered from human placental mitochondria and the kinetic parameters of tRNA aminoacylation determined. The effect of pathological point mutations present in the mitochondrial gene encoding tRNA Ile has been tackled by investigating the isoleucylation properties of wild-type and mutated in vitro transcripts. Data show that: (i) modified nucleotides contribute to efficient isoleucylation; (ii) point mutation A4269G in the gene (A→G at nt 7 in the tRNA), associated with a cardiomyopathy, does not affect aminoacylation significantly; (iii) point mutation A4317G (A→G at nt 59 in the tRNA), reported in a case of fatal infantile cardiomyopathy, induces a small but significant decrease in isoleucylation. The potential implications of these findings on the understanding of the molecular mechanisms involved in the expression of pathology are discussed.