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  • Crystallography, X-Ray  (3)
  • DNA methylation  (3)
  • 1
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    The structural basis for an essential subunit interaction in influenza virus RNA polymerase (2008)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2008-07-29
    Description: Influenza A virus is a major human and animal pathogen with the potential to cause catastrophic loss of life. The virus reproduces rapidly, mutates frequently and occasionally crosses species barriers. The recent emergence in Asia of avian influenza related to highly pathogenic forms of the human virus has highlighted the urgent need for new effective treatments. Here we demonstrate the importance to viral replication of a subunit interface in the viral RNA polymerase, thereby providing a new set of potential drug binding sites entirely independent of surface antigen type. No current medication targets this heterotrimeric polymerase complex. All three subunits, PB1, PB2 and PA, are required for both transcription and replication. PB1 carries the polymerase active site, PB2 includes the capped-RNA recognition domain, and PA is involved in assembly of the functional complex, but so far very little structural information has been reported for any of them. We describe the crystal structure of a large fragment of one subunit (PA) of influenza A RNA polymerase bound to a fragment of another subunit (PB1). The carboxy-terminal domain of PA forms a novel fold, and forms a deep, highly hydrophobic groove into which the amino-terminal residues of PB1 can fit by forming a 3(10) helix.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Obayashi, Eiji -- Yoshida, Hisashi -- Kawai, Fumihiro -- Shibayama, Naoya -- Kawaguchi, Atsushi -- Nagata, Kyosuke -- Tame, Jeremy R H -- Park, Sam-Yong -- England -- Nature. 2008 Aug 28;454(7208):1127-31. doi: 10.1038/nature07225. Epub 2008 Jul 27.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Protein Design Laboratory, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama 230-0045, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18660801" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Cell Line ; Crystallization ; Crystallography, X-Ray ; Humans ; Influenza A Virus, H1N1 Subtype/*enzymology/genetics ; Protein Binding ; Protein Subunits/*chemistry/genetics/*metabolism ; RNA Replicase/*chemistry/genetics/*metabolism ; Viral Proteins/*chemistry/genetics/*metabolism ; Virus Replication
    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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    Agrochemical control of plant water use using engineered abscisic acid receptors (2015)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2015-02-06
    Description: Rising temperatures and lessening fresh water supplies are threatening agricultural productivity and have motivated efforts to improve plant water use and drought tolerance. During water deficit, plants produce elevated levels of abscisic acid (ABA), which improves water consumption and stress tolerance by controlling guard cell aperture and other protective responses. One attractive strategy for controlling water use is to develop compounds that activate ABA receptors, but agonists approved for use have yet to be developed. In principle, an engineered ABA receptor that can be activated by an existing agrochemical could achieve this goal. Here we describe a variant of the ABA receptor PYRABACTIN RESISTANCE 1 (PYR1) that possesses nanomolar sensitivity to the agrochemical mandipropamid and demonstrate its efficacy for controlling ABA responses and drought tolerance in transgenic plants. Furthermore, crystallographic studies provide a mechanistic basis for its activity and demonstrate the relative ease with which the PYR1 ligand-binding pocket can be altered to accommodate new ligands. Thus, we have successfully repurposed an agrochemical for a new application using receptor engineering. We anticipate that this strategy will be applied to other plant receptors and represents a new avenue for crop improvement.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Park, Sang-Youl -- Peterson, Francis C -- Mosquna, Assaf -- Yao, Jin -- Volkman, Brian F -- Cutler, Sean R -- England -- Nature. 2015 Apr 23;520(7548):545-8. doi: 10.1038/nature14123. Epub 2015 Feb 4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA [2] Institute for Integrative Genome Biology, Riverside, California 92521, USA. ; Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25652827" target="_blank"〉PubMed〈/a〉
    Keywords: Abscisic Acid/*metabolism ; Acclimatization/drug effects ; Agrochemicals/*pharmacology ; Amides/*pharmacology ; Arabidopsis/drug effects/genetics/metabolism ; Arabidopsis Proteins/*genetics/*metabolism ; Binding Sites ; Carboxylic Acids/*pharmacology ; Crystallography, X-Ray ; Droughts ; Genetic Engineering ; Genotype ; Ligands ; Lycopersicon esculentum/drug effects/genetics/metabolism ; Membrane Transport Proteins/*genetics/*metabolism ; Models, Molecular ; Plant Transpiration/drug effects ; Plants/*drug effects/genetics/*metabolism ; Plants, Genetically Modified ; Stress, Physiological/drug effects ; Structure-Activity Relationship ; Water/*metabolism
    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 the human centromeric nucleosome containing CENP-A (2011)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2011-07-12
    Description: In eukaryotes, accurate chromosome segregation during mitosis and meiosis is coordinated by kinetochores, which are unique chromosomal sites for microtubule attachment. Centromeres specify the kinetochore formation sites on individual chromosomes, and are epigenetically marked by the assembly of nucleosomes containing the centromere-specific histone H3 variant, CENP-A. Although the underlying mechanism is unclear, centromere inheritance is probably dictated by the architecture of the centromeric nucleosome. Here we report the crystal structure of the human centromeric nucleosome containing CENP-A and its cognate alpha-satellite DNA derivative (147 base pairs). In the human CENP-A nucleosome, the DNA is wrapped around the histone octamer, consisting of two each of histones H2A, H2B, H4 and CENP-A, in a left-handed orientation. However, unlike the canonical H3 nucleosome, only the central 121 base pairs of the DNA are visible. The thirteen base pairs from both ends of the DNA are invisible in the crystal structure, and the alphaN helix of CENP-A is shorter than that of H3, which is known to be important for the orientation of the DNA ends in the canonical H3 nucleosome. A structural comparison of the CENP-A and H3 nucleosomes revealed that CENP-A contains two extra amino acid residues (Arg 80 and Gly 81) in the loop 1 region, which is completely exposed to the solvent. Mutations of the CENP-A loop 1 residues reduced CENP-A retention at the centromeres in human cells. Therefore, the CENP-A loop 1 may function in stabilizing the centromeric chromatin containing CENP-A, possibly by providing a binding site for trans-acting factors. The structure provides the first atomic-resolution picture of the centromere-specific nucleosome.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tachiwana, Hiroaki -- Kagawa, Wataru -- Shiga, Tatsuya -- Osakabe, Akihisa -- Miya, Yuta -- Saito, Kengo -- Hayashi-Takanaka, Yoko -- Oda, Takashi -- Sato, Mamoru -- Park, Sam-Yong -- Kimura, Hiroshi -- Kurumizaka, Hitoshi -- England -- Nature. 2011 Jul 10;476(7359):232-5. doi: 10.1038/nature10258.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21743476" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Autoantigens/*chemistry/metabolism ; Base Sequence ; Chromosomal Proteins, Non-Histone/*chemistry/metabolism ; Crystallography, X-Ray ; DNA/*chemistry/genetics/metabolism ; Histones/*chemistry/metabolism ; Humans ; Models, Molecular ; Molecular Conformation ; Molecular Sequence Data ; Nucleosomes/*chemistry/genetics/metabolism
    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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  • 4
    Electronic Resource
    Electronic Resource
    Susceptibility of transgene loci to homology-dependent gene silencing (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 230-241 
    Details
    ISSN: 1617-4623
    Keywords: DNA methylation ; Inbreeding depression ; Paramutation ; Somaclonal variation ; Trans-inactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous work has shown that two unlinked, partially homologous transgene loci can interact in plant nuclei, leading to reversible methylation and inactivation of one transgene locus in the presence of the second. To study whether the chromosomal location of a transgene influences its susceptibility to trans-inactivation, we retransformed four transgenic lines, which contained the same construct (H) integrated in different chromosomal locations, with a second, partially homologous construct (K). At least 50 double transformants (DTs) were regenerated from each single transformant (ST) and screened for inactivation of markers [chloramphenicol acetyltransferase (CAT); hygromycin resistance (HYGR)] at the resident H locus. For two STs, H locus markers were inactivated in less than 1% of the DTs, suggesting that, at these integration sites, H was relatively resistant to trans-inactivation. In contrast, the other two STs appeared to be more sensitive to trans-inactivation: 4–10% of the DTs were CAT− and/or HygS. Inactivation of H locus markers could be attributed to two distinct phenomena: 1. Regeneration from cells containing different epigenetic states of H, in which either both, one or none of the H alleles was active. This instability in the expression of the H locus, which was independent of K, was more pronounced in the homozygous state, and was associated with cellular mosaicism of expression and methylation. 2. The presence of an unlinked K locus could weaken the HygR phenotype by transcriptional inactivation and increased methylation of the hph gene at the H locus. These results indicated that a susceptible transgene locus is inherently unstable and partially methylated, and that these characteristics are exacerbated when the locus is homozygous for the transgene and/or when an unlinked homologous transgene is present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285450
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  • 5
    Electronic Resource
    Electronic Resource
    Inheritance and expression of a transgene insert in an aneuploid tobacco line (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 471-485 
    Details
    ISSN: 1617-4623
    Keywords: Aneuploidy ; DNA methylation ; Homology-dependent gene silencing ; Non-Mendelian inheritance ; T-DNA ; Trisomy/tetrasomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A T-DNA locus comprising nptII, uidA and nos genes — all under the control of the nos promoter (this locus was designated K because it encodes resistance to Kanamycin) - was found to be inherited erratically in a transgenic tobacco line. This anomalous behavior was partially explained following a karyotype analysis of plants representing several generations: these plants were aneuploids, presumably for the K-containing chromosome. During four generations of sexual propagation, transgenic plants that were either trisomic or tetrasomic for the K-containing chromosome (i.e. 2n=49 or 2n=50, respectively) were obtained. The trisomic plants (2n=48+1) were virtually indistinguishable phenotypically from normal euploids (2n=4x=48), whereas the tetrasomic plants (2n=48+2) were smaller, had somewhat misshapen leaves and exhibited reduced fertility. Although the amount of NPTH protein in different trisomic (K--, KK-, KKK) and tetrasomic (KK--, KKK-) plants was generally consistent with a K dosage effect, the genetic behavior of each trisomic — with respect to segregation of KanR and marker gene activity in progeny — was unique and not completely explicable by invoking aneuploidy. Specifically, unexpected gains or losses of K could occur, suggesting the formation of double reductional gametes and/or frequent gene conversion at this locus. The susceptibility of K locus marker genes to trans-inactivation in the trisomic and tetrasomic lines was tested by crossing in partially homologous silencing loci. In all transgenotypes tested, the three K marker genes were sensitive to trans-silencing, which was accompanied by methylation in all copies of the nos promoter. In addition to this directed inactivation/methylation, the K locus could also undergo infrequent, spontaneous partial methylation, which produced stable epialleles. In most plants, however, the multiple copies of the nos promoter at this locus remained unmethylated and active through four generations in all transgenotypes examined. The significance of these results for irregular inheritance patterns, aneuploid syndromes and homology-dependent gene silencing is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302260
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  • 6
    Electronic Resource
    Electronic Resource
    Homology-dependent gene silencing in transgenic plants: epistatic silencing loci contain multiple copies of methylated transgenes (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 219-229 
    Details
    ISSN: 1617-4623
    Keywords: DNA methylation ; Epigene conversion ; Homology-dependent gene silencing ; Methylation induced premeiotically (MIP) ; Trans-inactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous work has shown that two homologous, unlinked transgene loci can interact in plant nuclei, leading to non-reciprocal trans-inactivation and methylation of genes at one locus. Here, we report the structure and methylation of different transgene loci that contain the same construct but are variably able to inactivate and methylate a partially homologous, unlinked target locus. Silencing loci comprised multiple, methylated copies of the transgene construct, whereas a non-silencing locus contained a single, unmethylated copy. The correspondence between strength of silencing activity and copy number/degree of methylation was further demonstrated by producing novel alleles of a strong silencing locus: reducing the transgene copy number and methylation within this silencing locus decreased its ability to inactivate the target locus. The strong silencing locus, which was located close to a telomere, trans-inactivated various structural variants of the original target construct, regardless of their location in the genome. This suggests that the silencing locus can scan the entire genome for homologous regions, a process possibly aided by its telomeric location. Our data support the idea that epistatic trans-inactivation of unlinked, homologous transgenes in plants results from a pre-existing epigenetic difference between transgene loci, which is subsequently equalized by “epigene conversion” involving DNA-DNA pairing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285449
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