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  • 1
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    Two enzymes bound to one transfer RNA assume alternative conformations for consecutive reactions (2010)
    Nature Publishing Group (NPG)
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    Publication Date: 2010-10-01
    Description: In most bacteria and all archaea, glutamyl-tRNA synthetase (GluRS) glutamylates both tRNA(Glu) and tRNA(Gln), and then Glu-tRNA(Gln) is selectively converted to Gln-tRNA(Gln) by a tRNA-dependent amidotransferase. The mechanisms by which the two enzymes recognize their substrate tRNA(s), and how they cooperate with each other in Gln-tRNA(Gln) synthesis, remain to be determined. Here we report the formation of the 'glutamine transamidosome' from the bacterium Thermotoga maritima, consisting of tRNA(Gln), GluRS and the heterotrimeric amidotransferase GatCAB, and its crystal structure at 3.35 A resolution. The anticodon-binding body of GluRS recognizes the common features of tRNA(Gln) and tRNA(Glu), whereas the tail body of GatCAB recognizes the outer corner of the L-shaped tRNA(Gln) in a tRNA(Gln)-specific manner. GluRS is in the productive form, as its catalytic body binds to the amino-acid-acceptor arm of tRNA(Gln). In contrast, GatCAB is in the non-productive form: the catalytic body of GatCAB contacts that of GluRS and is located near the acceptor stem of tRNA(Gln), in an appropriate site to wait for the completion of Glu-tRNA(Gln) formation by GluRS. We identified the hinges between the catalytic and anticodon-binding bodies of GluRS and between the catalytic and tail bodies of GatCAB, which allow both GluRS and GatCAB to adopt the productive and non-productive forms. The catalytic bodies of the two enzymes compete for the acceptor arm of tRNA(Gln) and therefore cannot assume their productive forms simultaneously. The transition from the present glutamylation state, with the productive GluRS and the non-productive GatCAB, to the putative amidation state, with the non-productive GluRS and the productive GatCAB, requires an intermediate state with the two enzymes in their non-productive forms, for steric reasons. The proposed mechanism explains how the transamidosome efficiently performs the two consecutive steps of Gln-tRNA(Gln) formation, with a low risk of releasing the unstable intermediate Glu-tRNA(Gln).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ito, Takuhiro -- Yokoyama, Shigeyuki -- England -- Nature. 2010 Sep 30;467(7315):612-6. doi: 10.1038/nature09411.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20882017" target="_blank"〉PubMed〈/a〉
    Keywords: Anticodon/genetics ; Biocatalysis ; Crystallography, X-Ray ; Electrophoretic Mobility Shift Assay ; Glutamate-tRNA Ligase/*chemistry/*metabolism ; Models, Molecular ; Molecular Conformation ; Nitrogenous Group Transferases/*chemistry/*metabolism ; Protein Binding ; RNA, Transfer, Gln/biosynthesis/*chemistry/*metabolism ; RNA, Transfer, Glu/chemistry/metabolism ; Staphylococcus aureus/enzymology ; Substrate Specificity ; Thermotoga maritima/*enzymology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Rotation mechanism of Enterococcus hirae V1-ATPase based on asymmetric crystal structures (2013)
    Nature Publishing Group (NPG)
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    Publication Date: 2013-01-22
    Description: In various cellular membrane systems, vacuolar ATPases (V-ATPases) function as proton pumps, which are involved in many processes such as bone resorption and cancer metastasis, and these membrane proteins represent attractive drug targets for osteoporosis and cancer. The hydrophilic V(1) portion is known as a rotary motor, in which a central axis DF complex rotates inside a hexagonally arranged catalytic A(3)B(3) complex using ATP hydrolysis energy, but the molecular mechanism is not well defined owing to a lack of high-resolution structural information. We previously reported on the in vitro expression, purification and reconstitution of Enterococcus hirae V(1)-ATPase from the A(3)B(3) and DF complexes. Here we report the asymmetric structures of the nucleotide-free (2.8 A) and nucleotide-bound (3.4 A) A(3)B(3) complex that demonstrate conformational changes induced by nucleotide binding, suggesting a binding order in the right-handed rotational orientation in a cooperative manner. The crystal structures of the nucleotide-free (2.2 A) and nucleotide-bound (2.7 A) V(1)-ATPase are also reported. The more tightly packed nucleotide-binding site seems to be induced by DF binding, and ATP hydrolysis seems to be stimulated by the approach of a conserved arginine residue. To our knowledge, these asymmetric structures represent the first high-resolution view of the rotational mechanism of V(1)-ATPase.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Arai, Satoshi -- Saijo, Shinya -- Suzuki, Kano -- Mizutani, Kenji -- Kakinuma, Yoshimi -- Ishizuka-Katsura, Yoshiko -- Ohsawa, Noboru -- Terada, Takaho -- Shirouzu, Mikako -- Yokoyama, Shigeyuki -- Iwata, So -- Yamato, Ichiro -- Murata, Takeshi -- England -- Nature. 2013 Jan 31;493(7434):703-7. doi: 10.1038/nature11778. Epub 2013 Jan 13.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23334411" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Crystallization ; Enterococcus/*enzymology/genetics ; *Models, Molecular ; Mutation ; Nucleotides/metabolism ; Protein Binding ; Protein Structure, Tertiary ; Protein Subunits ; Rotation ; Vacuolar Proton-Translocating ATPases/*chemistry/genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    Crystal structure of eukaryotic translation initiation factor 2B (2016)
    Nature Publishing Group (NPG)
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    Publication Date: 2016-02-24
    Description: Eukaryotic cells restrict protein synthesis under various stress conditions, by inhibiting the eukaryotic translation initiation factor 2B (eIF2B). eIF2B is the guanine nucleotide exchange factor for eIF2, a heterotrimeric G protein consisting of alpha-, beta- and gamma-subunits. eIF2B exchanges GDP for GTP on the gamma-subunit of eIF2 (eIF2gamma), and is inhibited by stress-induced phosphorylation of eIF2alpha. eIF2B is a heterodecameric complex of two copies each of the alpha-, beta-, gamma-, delta- and epsilon-subunits; its alpha-, beta- and delta-subunits constitute the regulatory subcomplex, while the gamma- and epsilon-subunits form the catalytic subcomplex. The three-dimensional structure of the entire eIF2B complex has not been determined. Here we present the crystal structure of Schizosaccharomyces pombe eIF2B with an unprecedented subunit arrangement, in which the alpha2beta2delta2 hexameric regulatory subcomplex binds two gammaepsilon dimeric catalytic subcomplexes on its opposite sides. A structure-based in vitro analysis by a surface-scanning site-directed photo-cross-linking method identified the eIF2alpha-binding and eIF2gamma-binding interfaces, located far apart on the regulatory and catalytic subcomplexes, respectively. The eIF2gamma-binding interface is located close to the conserved 'NF motif', which is important for nucleotide exchange. A structural model was constructed for the complex of eIF2B with phosphorylated eIF2alpha, which binds to eIF2B more strongly than the unphosphorylated form. These results indicate that the eIF2alpha phosphorylation generates the 'nonproductive' eIF2-eIF2B complex, which prevents nucleotide exchange on eIF2gamma, and thus provide a structural framework for the eIF2B-mediated mechanism of stress-induced translational control.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kashiwagi, Kazuhiro -- Takahashi, Mari -- Nishimoto, Madoka -- Hiyama, Takuya B -- Higo, Toshiaki -- Umehara, Takashi -- Sakamoto, Kensaku -- Ito, Takuhiro -- Yokoyama, Shigeyuki -- England -- Nature. 2016 Mar 3;531(7592):122-5. doi: 10.1038/nature16991. Epub 2016 Feb 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan. ; RIKEN Systems and Structural Biology Center, Tsurumi-ku, Yokohama 230-0045, Japan. ; RIKEN Center for Life Science Technologies, Tsurumi-ku, Yokohama 230-0045, Japan. ; RIKEN Structural Biology Laboratory, Tsurumi-ku, Yokohama 230-0045, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26901872" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Motifs ; Binding Sites ; Biocatalysis ; Cross-Linking Reagents/chemistry ; Crystallography, X-Ray ; Eukaryotic Initiation Factor-2B/*chemistry/metabolism ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/metabolism ; Models, Molecular ; Phosphorylation ; Protein Binding ; Protein Biosynthesis ; Protein Structure, Quaternary ; Protein Subunits/chemistry/metabolism ; Schizosaccharomyces/*chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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