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  • 1
    Publication Date: 2009-10-23
    Description: Maturation of precursor transfer RNA (pre-tRNA) includes excision of the 5' leader and 3' trailer sequences, removal of introns and addition of the CCA terminus. Nucleotide modifications are incorporated at different stages of tRNA processing, after the RNA molecule adopts the proper conformation. In bacteria, tRNA(Ile2) lysidine synthetase (TilS) modifies cytidine into lysidine (L; 2-lysyl-cytidine) at the first anticodon of tRNA(Ile2) (refs 4-9). This modification switches tRNA(Ile2) from a methionine-specific to an isoleucine-specific tRNA. However, the aminoacylation of tRNA(Ile2) by methionyl-tRNA synthetase (MetRS), before the modification by TilS, might lead to the misincorporation of methionine in response to isoleucine codons. The mechanism used by bacteria to avoid this pitfall is unknown. Here we show that the TilS enzyme specifically recognizes and modifies tRNA(Ile2) in its precursor form, thereby avoiding translation errors. We identified the lysidine modification in pre-tRNA(Ile2) isolated from RNase-E-deficient Escherichia coli and did not detect mature tRNA(Ile2) lacking this modification. Our kinetic analyses revealed that TilS can modify both types of RNA molecule with comparable efficiencies. X-ray crystallography and mutational analyses revealed that TilS specifically recognizes the entire L-shape structure in pre-tRNA(Ile2) through extensive interactions coupled with sequential domain movements. Our results demonstrate how TilS prevents the recognition of tRNA(Ile2) by MetRS and achieves high specificity for its substrate. These two key points form the basis for maintaining the fidelity of isoleucine codon translation in bacteria. Our findings also provide a rationale for the necessity of incorporating specific modifications at the precursor level during tRNA biogenesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nakanishi, Kotaro -- Bonnefond, Luc -- Kimura, Satoshi -- Suzuki, Tsutomu -- Ishitani, Ryuichiro -- Nureki, Osamu -- England -- Nature. 2009 Oct 22;461(7267):1144-8. doi: 10.1038/nature08474.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa 225-8501, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19847269" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acyl-tRNA Synthetases/*chemistry/genetics/*metabolism ; Apoproteins/genetics/metabolism ; Bacillus subtilis ; Bacterial Proteins/*chemistry/genetics/*metabolism ; Base Sequence ; Catalytic Domain ; Crystallography, X-Ray ; Escherichia coli ; Geobacillus ; Kinetics ; Lysine/analogs & derivatives/metabolism ; Mass Spectrometry ; Models, Molecular ; Molecular Sequence Data ; *Protein Biosynthesis ; Pyrimidine Nucleosides/metabolism ; RNA, Transfer, Ile/genetics/metabolism ; Substrate Specificity
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-03-29
    Description: Multidrug and toxic compound extrusion (MATE) family transporters are conserved in the three primary domains of life (Archaea, Bacteria and Eukarya), and export xenobiotics using an electrochemical gradient of H(+) or Na(+) across the membrane. MATE transporters confer multidrug resistance to bacterial pathogens and cancer cells, thus causing critical reductions in the therapeutic efficacies of antibiotics and anti-cancer drugs, respectively. Therefore, the development of MATE inhibitors has long been awaited in the field of clinical medicine. Here we present the crystal structures of the H(+)-driven MATE transporter from Pyrococcus furiosus in two distinct apo-form conformations, and in complexes with a derivative of the antibacterial drug norfloxacin and three in vitro selected thioether-macrocyclic peptides, at 2.1-3.0 A resolutions. The structures, combined with functional analyses, show that the protonation of Asp 41 on the amino (N)-terminal lobe induces the bending of TM1, which in turn collapses the N-lobe cavity, thereby extruding the substrate drug to the extracellular space. Moreover, the macrocyclic peptides bind the central cleft in distinct manners, which correlate with their inhibitory activities. The strongest inhibitory peptide that occupies the N-lobe cavity may pave the way towards the development of efficient inhibitors against MATE transporters.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tanaka, Yoshiki -- Hipolito, Christopher J -- Maturana, Andres D -- Ito, Koichi -- Kuroda, Teruo -- Higuchi, Takashi -- Katoh, Takayuki -- Kato, Hideaki E -- Hattori, Motoyuki -- Kumazaki, Kaoru -- Tsukazaki, Tomoya -- Ishitani, Ryuichiro -- Suga, Hiroaki -- Nureki, Osamu -- England -- Nature. 2013 Apr 11;496(7444):247-51. doi: 10.1038/nature12014. Epub 2013 Mar 27.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23535598" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Antiporters/*chemistry/*metabolism ; Apoproteins/chemistry/metabolism ; Archaeal Proteins/*chemistry/*metabolism ; Aspartic Acid/chemistry ; Crystallography, X-Ray ; DNA Mutational Analysis ; Macrocyclic Compounds/chemistry/metabolism ; Models, Molecular ; Molecular Sequence Data ; Norfloxacin/chemistry/metabolism ; Peptides/chemistry/metabolism ; Protein Conformation ; Protons ; Pyrococcus furiosus/*chemistry ; Structure-Activity Relationship ; Sulfides/chemistry/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2012-10-16
    Description: PIWI-interacting RNAs (piRNAs) silence transposons to maintain genome integrity in animal germ lines. piRNAs are classified as primary and secondary piRNAs, depending on their biogenesis machinery. Primary piRNAs are processed from long non-coding RNA precursors transcribed from piRNA clusters in the genome through the primary processing pathway. Although the existence of a ribonuclease participating in this pathway has been predicted, its molecular identity remained unknown. Here we show that Zucchini (Zuc), a mitochondrial phospholipase D (PLD) superfamily member, is an endoribonuclease essential for primary piRNA biogenesis. We solved the crystal structure of Drosophila melanogaster Zuc (DmZuc) at 1.75 A resolution. The structure revealed that DmZuc has a positively charged, narrow catalytic groove at the dimer interface, which could accommodate a single-stranded, but not a double-stranded, RNA. DmZuc and the mouse homologue MmZuc (also known as Pld6 and MitoPLD) showed endoribonuclease activity for single-stranded RNAs in vitro. The RNA cleavage products bear a 5'-monophosphate group, a hallmark of mature piRNAs. Mutational analyses revealed that the conserved active-site residues of DmZuc are critical for the ribonuclease activity in vitro, and for piRNA maturation and transposon silencing in vivo. We propose a model for piRNA biogenesis in animal germ lines, in which the Zuc endoribonuclease has a key role in primary piRNA maturation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nishimasu, Hiroshi -- Ishizu, Hirotsugu -- Saito, Kuniaki -- Fukuhara, Satoshi -- Kamatani, Miharu K -- Bonnefond, Luc -- Matsumoto, Naoki -- Nishizawa, Tomohiro -- Nakanaga, Keita -- Aoki, Junken -- Ishitani, Ryuichiro -- Siomi, Haruhiko -- Siomi, Mikiko C -- Nureki, Osamu -- England -- Nature. 2012 Nov 8;491(7423):284-7. doi: 10.1038/nature11509. Epub 2012 Oct 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23064230" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Biocatalysis ; Catalytic Domain ; Crystallography, X-Ray ; DNA Transposable Elements/genetics ; Drosophila Proteins/*chemistry/*metabolism ; Drosophila melanogaster/*enzymology/genetics ; Endoribonucleases/*chemistry/*metabolism ; Gene Silencing ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; RNA, Small Interfering/biosynthesis/chemistry/genetics/*metabolism ; Structure-Activity Relationship
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2014-04-20
    Description: Tight junctions are cell-cell adhesion structures in epithelial cell sheets that surround organ compartments in multicellular organisms and regulate the permeation of ions through the intercellular space. Claudins are the major constituents of tight junctions and form strands that mediate cell adhesion and function as paracellular barriers. We report the structure of mammalian claudin-15 at a resolution of 2.4 angstroms. The structure reveals a characteristic beta-sheet fold comprising two extracellular segments, which is anchored to a transmembrane four-helix bundle by a consensus motif. Our analyses suggest potential paracellular pathways with distinctive charges on the extracellular surface, providing insight into the molecular basis of ion homeostasis across tight junctions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Suzuki, Hiroshi -- Nishizawa, Tomohiro -- Tani, Kazutoshi -- Yamazaki, Yuji -- Tamura, Atsushi -- Ishitani, Ryuichiro -- Dohmae, Naoshi -- Tsukita, Sachiko -- Nureki, Osamu -- Fujiyoshi, Yoshinori -- New York, N.Y. -- Science. 2014 Apr 18;344(6181):304-7. doi: 10.1126/science.1248571.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24744376" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Motifs ; Amino Acid Sequence ; Animals ; Claudins/*chemistry ; Crystallography, X-Ray ; Mice ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Protein Subunits/chemistry ; Static Electricity ; Tight Junctions/*chemistry/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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