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Emmanuelle Schmitt – One of the best experts on this subject based on the ideXlab platform.

  • Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation
    Communications Biology, 2020
    Co-Authors: Pierre-damien Coureux, Yves Mechulam, Christine Lazennec-Schurdevin, Sophie Bourcier, Emmanuelle Schmitt
    Abstract:

    Archaeal translation initiation occurs within a macromolecular complex containing the small riboribosomal subunit (30S) bound to mRNA, initiation factors AIF1, AIF1A and the ternary complex aIF2:GDPNP:Met-tRNAiMet. Here, we determine the cryo-EM structure of a 30S:mRNA:AIF1A:aIF2:GTP:Met-tRNAiMet complex from Pyrococcus abyssi at 3.2 Å resolution. It highlights archaeal features in ribosomal proteins and rRNA modifications. We find an aS21 protein, at the location of eS21 in eukaryotic ribosomes. Moreover, we identify an N-terminal extension of archaeal eL41 contacting the P site. We characterize 34 N4-acetylcytidines distributed throughout 16S rRNA, likely contributing to hyperthermostability. Without AIF1, the 30S head is stabilized and initiator tRNA is tightly bound to the P site. A network of interactions involving tRNA, mRNA, rRNA modified nucleotides and C-terminal tails of uS9, uS13 and uS19 is observed. Universal features and domain-specific idiosyncrasies of translation initiation are discussed in light of ribosomal structures from representatives of each domain of life.

  • Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation.
    Communications biology, 2020
    Co-Authors: Pierre-damien Coureux, Yves Mechulam, Christine Lazennec-Schurdevin, Sophie Bourcier, Emmanuelle Schmitt
    Abstract:

    Archaeal translation initiation occurs within a macromolecular complex containing the small riboribosomal subunit (30S) bound to mRNA, initiation factors AIF1, AIF1A and the ternary complex aIF2:GDPNP:Met-tRNAiMet. Here, we determine the cryo-EM structure of a 30S:mRNA:AIF1A:aIF2:GTP:Met-tRNAiMet complex from Pyrococcus abyssi at 3.2 A resolution. It highlights archaeal features in ribosomal proteins and rRNA modifications. We find an aS21 protein, at the location of eS21 in eukaryotic ribosomes. Moreover, we identify an N-terminal extension of archaeal eL41 contacting the P site. We characterize 34 N4-acetylcytidines distributed throughout 16S rRNA, likely contributing to hyperthermostability. Without AIF1, the 30S head is stabilized and initiator tRNA is tightly bound to the P site. A network of interactions involving tRNA, mRNA, rRNA modified nucleotides and C-terminal tails of uS9, uS13 and uS19 is observed. Universal features and domain-specific idiosyncrasies of translation initiation are discussed in light of ribosomal structures from representatives of each domain of life. Coureux et al. describe a cryo-EM structure of a 30S initiation complex of Pyrococcus abyssi at 3.2A resolution. The structure uncovers a novel archaeal ribosomal protein aS21, N-terminal extension of eL41 and brings insights into base modifications of the rRNA.

  • Start Codon Recognition in Eukaryotic and Archaeal Translation Initiation: A Common Structural Core
    International Journal of Molecular Sciences, 2019
    Co-Authors: Emmanuelle Schmitt, Etienne Dubiez, Auriane Monestier, Pierre-damien Coureux, Yves Mechulam
    Abstract:

    Understanding molecular mechanisms of ribosomal translation sheds light on the emergence and evolution of protein synthesis in the three domains of life. Universally, ribosomal translation is described in three steps: initiation, elongation and termination. During initiation, a macromolecular complex assembled around the small riboribosomal subunit selects the start codon on the mRNA and defines the open reading frame. In this review, we focus on the comparison of start codon selection mechanisms in eukaryotes and archaea. Eukaryotic translation initiation is a very complicated process, involving many initiation factors. The most widespread mechanism for the discovery of the start codon is the scanning of the mRNA by a pre-initiation complex until the first AUG codon in a correct context is found. In archaea, long-range scanning does not occur because of the presence of Shine-Dalgarno (SD) sequences or of short 5′ untranslated regions. However, archaeal and eukaryotic translation initiations have three initiation factors in common: e/AIF1, e/AIF1A and e/aIF2 are directly involved in the selection of the start codon. Therefore, the idea that these archaeal and eukaryotic factors fulfill similar functions within a common structural ribosomal core complex has emerged. A divergence between eukaryotic and archaeal factors allowed for the adaptation to the long-range scanning process versus the SD mediated prepositioning of the ribosome.

Yves Mechulam – One of the best experts on this subject based on the ideXlab platform.

  • Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation
    Communications Biology, 2020
    Co-Authors: Pierre-damien Coureux, Yves Mechulam, Christine Lazennec-Schurdevin, Sophie Bourcier, Emmanuelle Schmitt
    Abstract:

    Archaeal translation initiation occurs within a macromolecular complex containing the small ribosomal subunit (30S) bound to mRNA, initiation factors AIF1, AIF1A and the ternary complex aIF2:GDPNP:Met-tRNAiMet. Here, we determine the cryo-EM structure of a 30S:mRNA:AIF1A:aIF2:GTP:Met-tRNAiMet complex from Pyrococcus abyssi at 3.2 Å resolution. It highlights archaeal features in ribosomal proteins and rRNA modifications. We find an aS21 protein, at the location of eS21 in eukaryotic ribosomes. Moreover, we identify an N-terminal extension of archaeal eL41 contacting the P site. We characterize 34 N4-acetylcytidines distributed throughout 16S rRNA, likely contributing to hyperthermostability. Without AIF1, the 30S head is stabilized and initiator tRNA is tightly bound to the P site. A network of interactions involving tRNA, mRNA, rRNA modified nucleotides and C-terminal tails of uS9, uS13 and uS19 is observed. Universal features and domain-specific idiosyncrasies of translation initiation are discussed in light of ribosomal structures from representatives of each domain of life.

  • Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation.
    Communications biology, 2020
    Co-Authors: Pierre-damien Coureux, Yves Mechulam, Christine Lazennec-Schurdevin, Sophie Bourcier, Emmanuelle Schmitt
    Abstract:

    Archaeal translation initiation occurs within a macromolecular complex containing the small ribosomal subunit (30S) bound to mRNA, initiation factors AIF1, AIF1A and the ternary complex aIF2:GDPNP:Met-tRNAiMet. Here, we determine the cryo-EM structure of a 30S:mRNA:AIF1A:aIF2:GTP:Met-tRNAiMet complex from Pyrococcus abyssi at 3.2 A resolution. It highlights archaeal features in ribosomal proteins and rRNA modifications. We find an aS21 protein, at the location of eS21 in eukaryotic ribosomes. Moreover, we identify an N-terminal extension of archaeal eL41 contacting the P site. We characterize 34 N4-acetylcytidines distributed throughout 16S rRNA, likely contributing to hyperthermostability. Without AIF1, the 30S head is stabilized and initiator tRNA is tightly bound to the P site. A network of interactions involving tRNA, mRNA, rRNA modified nucleotides and C-terminal tails of uS9, uS13 and uS19 is observed. Universal features and domain-specific idiosyncrasies of translation initiation are discussed in light of ribosomal structures from representatives of each domain of life. Coureux et al. describe a cryo-EM structure of a 30S initiation complex of Pyrococcus abyssi at 3.2A resolution. The structure uncovers a novel archaeal ribosomal protein aS21, N-terminal extension of eL41 and brings insights into base modifications of the rRNA.

  • Start Codon Recognition in Eukaryotic and Archaeal Translation Initiation: A Common Structural Core
    International Journal of Molecular Sciences, 2019
    Co-Authors: Emmanuelle Schmitt, Etienne Dubiez, Auriane Monestier, Pierre-damien Coureux, Yves Mechulam
    Abstract:

    Understanding molecular mechanisms of ribosomal translation sheds light on the emergence and evolution of protein synthesis in the three domains of life. Universally, ribosomal translation is described in three steps: initiation, elongation and termination. During initiation, a macromolecular complex assembled around the small ribosomal subunit selects the start codon on the mRNA and defines the open reading frame. In this review, we focus on the comparison of start codon selection mechanisms in eukaryotes and archaea. Eukaryotic translation initiation is a very complicated process, involving many initiation factors. The most widespread mechanism for the discovery of the start codon is the scanning of the mRNA by a pre-initiation complex until the first AUG codon in a correct context is found. In archaea, long-range scanning does not occur because of the presence of Shine-Dalgarno (SD) sequences or of short 5′ untranslated regions. However, archaeal and eukaryotic translation initiations have three initiation factors in common: e/AIF1, e/AIF1A and e/aIF2 are directly involved in the selection of the start codon. Therefore, the idea that these archaeal and eukaryotic factors fulfill similar functions within a common structural ribosomal core complex has emerged. A divergence between eukaryotic and archaeal factors allowed for the adaptation to the long-range scanning process versus the SD mediated prepositioning of the ribosome.

Udo Bläsi – One of the best experts on this subject based on the ideXlab platform.

  • Translation initiation complex formation in the crenarchaeon Sulfolobus solfataricus
    RNA (New York N.Y.), 2009
    Co-Authors: David Hasenohrl, Paola Londei, Attilio Fabbretti, Udo Bläsi
    Abstract:

    The function of initiation factors in and the sequence of events during translation initiation have been intensively studied in Bacteria and Eukaryotes, whereas in Archaea knowledge on these functions/processes is limited. By employing chemical probing, we show that translation initiation factor AIF1 of the model crenarchaeon Sulfolobus solfataricus binds to the same area on the ribosome as the bacterial and eukaryal orthologs. Fluorescence energy transfer assays (FRET) showed that AIF1, like its eukaryotic and bacterial orthologs, has a fidelity function in translation initiation compcomplex formation, and that both AIF1 and AIF1A exert a synergistic effect in stimulating ribosomal association of the Met-tRNAiMet binding factor a/eIF2. However, as in Eukaryotes their effect on a/eIF2 binding appears to be indirect. Moreover, FRET was used to analyze for the first time the sequence of events toward translation initiation compcomplex formation in an archaeal model system. These studies suggested that a/eIF2-GTP binds first to the ribosome and then recruits Met-tRNAiMet, which appears to comply with the operational mode of bacterial IF2, and deviates from the shuttle function of the eukaryotic counterpart eIF2. Thus, despite the resemblance of eIF2 and a/eIF2, recruitment of initiator tRNA to the ribosome is mechanistically different in Pro- and Eukaryotes.

  • sulfolobus solfataricus translation initiation factor 1 stimulates translation initiation complex formation
    RNA, 2006
    Co-Authors: David Hasenohrl, Dario Benelli, A Barbazza, Paola Londei, Udo Bläsi
    Abstract:

    The eukaryotic translation initiation factor 1 binds to the ribosome during translation initiation. It is instrumental for initiator-tRNA and mRNA binding, and has a function in selection of the authentic start codon. Here, we show that the archaeal homolog AIF1 has analogous functions. The AIF1 protein of the archaeon Sulfolobus solfataricus is bound to the small riboribosomal subunit during translation initiation and accelerates binding of initiator-tRNA and mRNA to the ribosome. Accordingly, AIF1 stimulated translation of an mRNA in a S. solfataricus in vitro translation system. Moreover, this study suggested that the C terminus of the factor is of relevance for its function.

Pierre-damien Coureux – One of the best experts on this subject based on the ideXlab platform.

  • Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation
    Communications Biology, 2020
    Co-Authors: Pierre-damien Coureux, Yves Mechulam, Christine Lazennec-Schurdevin, Sophie Bourcier, Emmanuelle Schmitt
    Abstract:

    Archaeal translation initiation occurs within a macromolecular complex containing the small ribosomal subunit (30S) bound to mRNA, initiation factors AIF1, AIF1A and the ternary complex aIF2:GDPNP:Met-tRNAiMet. Here, we determine the cryo-EM structure of a 30S:mRNA:AIF1A:aIF2:GTP:Met-tRNAiMet complex from Pyrococcus abyssi at 3.2 Å resolution. It highlights archaeal features in ribosomal proteins and rRNA modifications. We find an aS21 protein, at the location of eS21 in eukaryotic ribosomes. Moreover, we identify an N-terminal extension of archaeal eL41 contacting the P site. We characterize 34 N4-acetylcytidines distributed throughout 16S rRNA, likely contributing to hyperthermostability. Without AIF1, the 30S head is stabilized and initiator tRNA is tightly bound to the P site. A network of interactions involving tRNA, mRNA, rRNA modified nucleotides and C-terminal tails of uS9, uS13 and uS19 is observed. Universal features and domain-specific idiosyncrasies of translation initiation are discussed in light of ribosomal structures from representatives of each domain of life.

  • Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation.
    Communications biology, 2020
    Co-Authors: Pierre-damien Coureux, Yves Mechulam, Christine Lazennec-Schurdevin, Sophie Bourcier, Emmanuelle Schmitt
    Abstract:

    Archaeal translation initiation occurs within a macromolecular complex containing the small ribosomal subunit (30S) bound to mRNA, initiation factors AIF1, AIF1A and the ternary complex aIF2:GDPNP:Met-tRNAiMet. Here, we determine the cryo-EM structure of a 30S:mRNA:AIF1A:aIF2:GTP:Met-tRNAiMet complex from Pyrococcus abyssi at 3.2 A resolution. It highlights archaeal features in ribosomal proteins and rRNA modifications. We find an aS21 protein, at the location of eS21 in eukaryotic ribosomes. Moreover, we identify an N-terminal extension of archaeal eL41 contacting the P site. We characterize 34 N4-acetylcytidines distributed throughout 16S rRNA, likely contributing to hyperthermostability. Without AIF1, the 30S head is stabilized and initiator tRNA is tightly bound to the P site. A network of interactions involving tRNA, mRNA, rRNA modified nucleotides and C-terminal tails of uS9, uS13 and uS19 is observed. Universal features and domain-specific idiosyncrasies of translation initiation are discussed in light of ribosomal structures from representatives of each domain of life. Coureux et al. describe a cryo-EM structure of a 30S initiation complex of Pyrococcus abyssi at 3.2A resolution. The structure uncovers a novel archaeal ribosomal protein aS21, N-terminal extension of eL41 and brings insights into base modifications of the rRNA.

  • Start Codon Recognition in Eukaryotic and Archaeal Translation Initiation: A Common Structural Core
    International Journal of Molecular Sciences, 2019
    Co-Authors: Emmanuelle Schmitt, Etienne Dubiez, Auriane Monestier, Pierre-damien Coureux, Yves Mechulam
    Abstract:

    Understanding molecular mechanisms of ribosomal translation sheds light on the emergence and evolution of protein synthesis in the three domains of life. Universally, ribosomal translation is described in three steps: initiation, elongation and termination. During initiation, a macromolecular complex assembled around the small ribosomal subunit selects the start codon on the mRNA and defines the open reading frame. In this review, we focus on the comparison of start codon selection mechanisms in eukaryotes and archaea. Eukaryotic translation initiation is a very complicated process, involving many initiation factors. The most widespread mechanism for the discovery of the start codon is the scanning of the mRNA by a pre-initiation complex until the first AUG codon in a correct context is found. In archaea, long-range scanning does not occur because of the presence of Shine-Dalgarno (SD) sequences or of short 5′ untranslated regions. However, archaeal and eukaryotic translation initiations have three initiation factors in common: e/AIF1, e/AIF1A and e/aIF2 are directly involved in the selection of the start codon. Therefore, the idea that these archaeal and eukaryotic factors fulfill similar functions within a common structural ribosomal core complex has emerged. A divergence between eukaryotic and archaeal factors allowed for the adaptation to the long-range scanning process versus the SD mediated prepositioning of the ribosome.

David Hasenohrl – One of the best experts on this subject based on the ideXlab platform.

  • Translation initiation complex formation in the crenarchaeon Sulfolobus solfataricus
    RNA (New York N.Y.), 2009
    Co-Authors: David Hasenohrl, Paola Londei, Attilio Fabbretti, Udo Bläsi
    Abstract:

    The function of initiation factors in and the sequence of events during translation initiation have been intensively studied in Bacteria and Eukaryotes, whereas in Archaea knowledge on these functions/processes is limited. By employing chemical probing, we show that translation initiation factor AIF1 of the model crenarchaeon Sulfolobus solfataricus binds to the same area on the ribosome as the bacterial and eukaryal orthologs. Fluorescence energy transfer assays (FRET) showed that AIF1, like its eukaryotic and bacterial orthologs, has a fidelity function in translation initiation complex formation, and that both AIF1 and AIF1A exert a synergistic effect in stimulating ribosomal association of the Met-tRNAiMet binding factor a/eIF2. However, as in Eukaryotes their effect on a/eIF2 binding appears to be indirect. Moreover, FRET was used to analyze for the first time the sequence of events toward translation initiation complex formation in an archaeal model system. These studies suggested that a/eIF2-GTP binds first to the ribosome and then recruits Met-tRNAiMet, which appears to comply with the operational mode of bacterial IF2, and deviates from the shuttle function of the eukaryotic counterpart eIF2. Thus, despite the resemblance of eIF2 and a/eIF2, recruitment of initiator tRNA to the ribosome is mechanistically different in Pro- and Eukaryotes.

  • sulfolobus solfataricus translation initiation factor 1 stimulates translation initiation complex formation
    RNA, 2006
    Co-Authors: David Hasenohrl, Dario Benelli, A Barbazza, Paola Londei, Udo Bläsi
    Abstract:

    The eukaryotic translation initiation factor 1 binds to the ribosome during translation initiation. It is instrumental for initiator-tRNA and mRNA binding, and has a function in selection of the authentic start codon. Here, we show that the archaeal homolog AIF1 has analogous functions. The AIF1 protein of the archaeon Sulfolobus solfataricus is bound to the small ribosomal subunit during translation initiation and accelerates binding of initiator-tRNA and mRNA to the ribosome. Accordingly, AIF1 stimulated translation of an mRNA in a S. solfataricus in vitro translation system. Moreover, this study suggested that the C terminus of the factor is of relevance for its function.