Primer list used for the determination of chromosome ends structure in Encephalitozoon cuniculi. ... more Primer list used for the determination of chromosome ends structure in Encephalitozoon cuniculi. (DOC 85 kb)
Miropeat analysis of E. cuniculi chromosomes. Miropeat analysis was performed on various set of s... more Miropeat analysis of E. cuniculi chromosomes. Miropeat analysis was performed on various set of sequences. The three-by-three analysis was performed to extract coordinates of "r" sequence blocks. A. Comparative analysis of the 11 E. cuniculi chromosomes. Most repeated sequences are associated to chromosome extremities. B. Three-by-three analysis confirming the existence of sequence block. Left: comparison of chromosome I, IV and VIII enables the identification of r01, r02, r03, r04 repeats. The r15 sequence was found by comparison of chromosome I with itself. Part of r02, r03, R04 and r15 repeats will composed the EXT1 sequence block. Figure S2. Miropeat – EXT correspondence. A. Superimposed distributions of repeated elements detected with Miropeat software (boxes r01 to r02), EXT blocks (coloured arrows 1 to 10). The r01 repeat includes one rDNA unit (red arrow) and r04 is ascribed to dhfr-ts (dihydofolate reductase - thymidylate synthase) gene cluster. Five DNA segments ...
The microsporidian Encephalitozoon cuniculi is an obligate intracellular eukaryotic pathogen with... more The microsporidian Encephalitozoon cuniculi is an obligate intracellular eukaryotic pathogen with a small nuclear genome (2.9 Mbp) consisting of 11 chromosomes. Although each chromosome end is known to contain a single rDNA unit, the incomplete assembly of subtelomeric regions following sequencing of the genome identified only 3 of the 22 expected rDNA units. While chromosome end assembly remains a difficult process in most eukaryotic genomes, it is of significant importance for pathogens because these regions encode factors important for virulence and host evasion. Here we report the first complete assembly of E. cuniculi chromosome ends, and describe a novel mosaic structure of segmental duplications (EXT repeats) in these regions. EXT repeats range in size between 3.5 and 23.8 kbp and contain four multigene families encoding membrane associated proteins. Twenty-one recombination sites were identified in the sub-terminal region of E. cuniculi chromosomes. Our analysis suggests tha...
Proceedings of the National Academy of Sciences, 2000
Cysteinyl-tRNA (Cys-tRNA) is essential for protein synthesis. In most organisms the enzyme respon... more Cysteinyl-tRNA (Cys-tRNA) is essential for protein synthesis. In most organisms the enzyme responsible for the formation of Cys-tRNA is cysteinyl-tRNA synthetase (CysRS). The only known exceptions are the euryarchaea Methanococcus jannaschii and Methanobacterium thermoautotrophicum, which do not encode a CysRS. Deviating from the accepted concept of one aminoacyl-tRNA synthetase per amino acid, these organisms employ prolyl-tRNA synthetase as the enzyme that carries out Cys-tRNA formation. To date this dual-specificity prolyl-cysteinyl-tRNA synthetase (ProCysRS) is only known to exist in archaea. Analysis of the preliminary genomic sequence of the primitive eukaryote Giardia lamblia indicated the presence of an archaeal prolyl-tRNA synthetase (ProRS). Its proS gene was cloned and the gene product overexpressed in Escherichia coli. By using G. lamblia, M. jannaschii, or E. coli tRNA as substrate, this ProRS was able to form Cys-tRNA and Pro-tRNA in vitro. Cys-AMP formation, but not Pro-AMP synthesis, was tRNA-dependent. The in vitro data were confirmed in vivo, as the cloned G. lamblia proS gene was able to complement a temperature-sensitive E. coli cysS strain. Inhibition studies of CysRS activity with proline analogs (thiaproline and 5'-O-[N-(l-prolyl)-sulfamoyl]adenosine) in a Giardia S-100 extract predicted that the organism also contains a canonical CysRS. This prediction was confirmed by cloning and analysis of the corresponding cysS gene. Like a number of archaea, Giardia contains two enzymes, ProCysRS and CysRS, for Cys-tRNA formation. In contrast, the purified Saccharomyces cerevisiae and E. coli ProRS enzymes were unable to form Cys-tRNA under these conditions. Thus, the dual specificity is restricted to the archaeal genre of ProRS. G. lamblia's archaeal-type prolyl- and alanyl-tRNA synthetases refine our understanding of the evolution and interaction of archaeal and eukaryal translation systems.
Primer list used for the determination of chromosome ends structure in Encephalitozoon cuniculi. ... more Primer list used for the determination of chromosome ends structure in Encephalitozoon cuniculi. (DOC 85 kb)
Miropeat analysis of E. cuniculi chromosomes. Miropeat analysis was performed on various set of s... more Miropeat analysis of E. cuniculi chromosomes. Miropeat analysis was performed on various set of sequences. The three-by-three analysis was performed to extract coordinates of "r" sequence blocks. A. Comparative analysis of the 11 E. cuniculi chromosomes. Most repeated sequences are associated to chromosome extremities. B. Three-by-three analysis confirming the existence of sequence block. Left: comparison of chromosome I, IV and VIII enables the identification of r01, r02, r03, r04 repeats. The r15 sequence was found by comparison of chromosome I with itself. Part of r02, r03, R04 and r15 repeats will composed the EXT1 sequence block. Figure S2. Miropeat – EXT correspondence. A. Superimposed distributions of repeated elements detected with Miropeat software (boxes r01 to r02), EXT blocks (coloured arrows 1 to 10). The r01 repeat includes one rDNA unit (red arrow) and r04 is ascribed to dhfr-ts (dihydofolate reductase - thymidylate synthase) gene cluster. Five DNA segments ...
The microsporidian Encephalitozoon cuniculi is an obligate intracellular eukaryotic pathogen with... more The microsporidian Encephalitozoon cuniculi is an obligate intracellular eukaryotic pathogen with a small nuclear genome (2.9 Mbp) consisting of 11 chromosomes. Although each chromosome end is known to contain a single rDNA unit, the incomplete assembly of subtelomeric regions following sequencing of the genome identified only 3 of the 22 expected rDNA units. While chromosome end assembly remains a difficult process in most eukaryotic genomes, it is of significant importance for pathogens because these regions encode factors important for virulence and host evasion. Here we report the first complete assembly of E. cuniculi chromosome ends, and describe a novel mosaic structure of segmental duplications (EXT repeats) in these regions. EXT repeats range in size between 3.5 and 23.8 kbp and contain four multigene families encoding membrane associated proteins. Twenty-one recombination sites were identified in the sub-terminal region of E. cuniculi chromosomes. Our analysis suggests tha...
Proceedings of the National Academy of Sciences, 2000
Cysteinyl-tRNA (Cys-tRNA) is essential for protein synthesis. In most organisms the enzyme respon... more Cysteinyl-tRNA (Cys-tRNA) is essential for protein synthesis. In most organisms the enzyme responsible for the formation of Cys-tRNA is cysteinyl-tRNA synthetase (CysRS). The only known exceptions are the euryarchaea Methanococcus jannaschii and Methanobacterium thermoautotrophicum, which do not encode a CysRS. Deviating from the accepted concept of one aminoacyl-tRNA synthetase per amino acid, these organisms employ prolyl-tRNA synthetase as the enzyme that carries out Cys-tRNA formation. To date this dual-specificity prolyl-cysteinyl-tRNA synthetase (ProCysRS) is only known to exist in archaea. Analysis of the preliminary genomic sequence of the primitive eukaryote Giardia lamblia indicated the presence of an archaeal prolyl-tRNA synthetase (ProRS). Its proS gene was cloned and the gene product overexpressed in Escherichia coli. By using G. lamblia, M. jannaschii, or E. coli tRNA as substrate, this ProRS was able to form Cys-tRNA and Pro-tRNA in vitro. Cys-AMP formation, but not Pro-AMP synthesis, was tRNA-dependent. The in vitro data were confirmed in vivo, as the cloned G. lamblia proS gene was able to complement a temperature-sensitive E. coli cysS strain. Inhibition studies of CysRS activity with proline analogs (thiaproline and 5'-O-[N-(l-prolyl)-sulfamoyl]adenosine) in a Giardia S-100 extract predicted that the organism also contains a canonical CysRS. This prediction was confirmed by cloning and analysis of the corresponding cysS gene. Like a number of archaea, Giardia contains two enzymes, ProCysRS and CysRS, for Cys-tRNA formation. In contrast, the purified Saccharomyces cerevisiae and E. coli ProRS enzymes were unable to form Cys-tRNA under these conditions. Thus, the dual specificity is restricted to the archaeal genre of ProRS. G. lamblia's archaeal-type prolyl- and alanyl-tRNA synthetases refine our understanding of the evolution and interaction of archaeal and eukaryal translation systems.
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Papers by Christian Vivarès