日本結晶学会誌
Online ISSN : 1884-5576
Print ISSN : 0369-4585
ISSN-L : 0369-4585
59 巻 , 2-3 号
選択された号の論文の15件中1~15を表示しています
連載企画 対称性と群論(2)
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  • 松井 崇
    2017 年 59 巻 2-3 号 p. 96-101
    発行日: 2017/06/30
    公開日: 2017/07/01
    ジャーナル フリー

    Pheganomycins(PGMs)derived from Streptomyces cirratus are one of the peptide antibiotics and synthesized under the cooperation of a novel peptide ligase, PGM1, and ribosome, in contrast of typical peptide antibiotics. In the biosynthesis, PGM1, which is a peptide ligase with broad substrate permissivity, can catalyze the linkage between several types of nonproteinogenic amino acid including a 2-guanidino group and some ribosomal peptides to generate N-terminal capping peptide. Herein, I present structural studies for the recognition mechanisms of N-terminal capping substrates and C-terminal ribosomal peptides.

  • 大木 規央, 朴 三用
    2017 年 59 巻 2-3 号 p. 102-107
    発行日: 2017/06/30
    公開日: 2017/07/01
    ジャーナル フリー

    Cyclic-AMP is one of the most important second messengers,regulating many crucial cellular events in both prokaryotes and eukaryotes. Precise spatial and temporal control of cAMP levels by light shows great promise as a simple means of manipulating and studying numerous cell pathways and processes. The photoactivated adenylate cyclase(PAC)from the photosynthetic cyanobacterium Oscillatoria acuminata is a small homodimer eminently suitable for this task,requiring only a simple flavin as chromophore. Here we describe its structure using X-ray crystallography and crystal microspectrophotometry. Site-directed mutants show signal transduction over 30 Ångstroms across the protein with minimal conformational rearrangement. The use of the protein in living human cells is demonstrated with cAMP-dependent luciferase,showing a rapid and stable response to light over many hours and activation cycles.

  • 石田 英子, 大戸 梅治, 清水 敏之
    2017 年 59 巻 2-3 号 p. 108-113
    発行日: 2017/06/30
    公開日: 2017/07/01
    ジャーナル フリー

    Fertilization, the crucial step in sexual reproduction, requires the fusion of haploid sperm and egg to create a genetically distinct offspring. Despite many studies on mammalian fertilization, the molecular mechanisms underlining the membrane fusion remain largely unknown. At present, IZUMO1 on the sperm surface and JUNO on the egg surface are known as the only protein pair essential for fertilization. In this review, we focus on the crystal structures of human IZUMO1, JUNO and IZUMO1-JUNO complex. These structures reveal the molecular mechanism of mammalian gamete recognition, and provide information for development of non-hormonal contraceptive agents.

  • 桑原 直之, 加藤 龍一, 萬谷 博, 遠藤 玉夫
    2017 年 59 巻 2-3 号 p. 114-120
    発行日: 2017/06/30
    公開日: 2017/07/01
    ジャーナル フリー

    The dystrophin glycoprotein complex, which connects the cell membrane to the basement membrane, is essential for a variety of biological events, including maintenance of muscle integrity. An O-mannose-type GalNAc-β3-GlcNAc-β4-Man(-6-phosphate)(core M3) structure of α-dystroglycan (αDG), a subunit of the complex that is anchored to the cell membrane, interacts directly with laminin in the basement membrane. Hypo-glycosylation of αDG is linked to some types of inherited muscular dystrophy; consistent with this relationship, many disease-related mutations have been detected in genes involved in O-mannosyl glycan synthesis. Defects in protein O-linked mannose β1,2-N-acetylglucosaminyltransferase 1 (POMGnT1), a glycosyltransferase that participates in the formation of GlcNAc-β2-Man glycan, are causally related to muscle-eye-brain disease (MEB), a congenital muscular dystrophy, although the role of POMGnT1 in post-phosphoryl modification of core M3 glycan remains elusive. We found that N-terminal domain of POMGnT1 (called stem domain) recognizes the β-linked GlcNAc of O-mannosyl glycan, an enzymatic product of POMGnT1. This interaction may recruit POMGnT1 to a specific site of α-DG to promote GlcNAc-β2-Man (core M1) clustering and also may recruit other enzymes that interact with POMGnT1, e.g., FKTN which is required for ribitol-phosphate modification of the core M3 glycan that is the first step of post-phosphoryl modification of core M3 glycan. These findings explain how POMGnT1 attaches GlcNAc-β to clustered O-mannose sites and influences post-phosphoryl modification of core M3. Our study provides important insight into how disease-associated mutations cause inherited muscular dystrophy pathogenesis.

  • 菊池 壮太郎, Hongtao YU
    2017 年 59 巻 2-3 号 p. 121-126
    発行日: 2017/06/30
    公開日: 2017/07/01
    ジャーナル フリー

    The ring-shaped cohesin complex entraps chromosomes and regulates chromosome biology. The cohesin core consists of Smc1, Smc3, Scc1 and Scc3. Scc2-Scc4 complex is known as a cohesin loader and loads cohesin onto chromosomes. Mutations of Scc2 cause human developmental diseases termed cohesinopathy. Here we determined the crystal structure of Chaetomium thermophilum(Ct)Scc2 and its interaction with cohesin. The structure consists mostly of HEAT repeats and it forms a hook-shaped structure that similar with Scc3 and Pds5. Many cohesinopathy mutations in Scc2 diminish the Scc2- Scc1 interaction. Our study defines a functionally important interaction between cohesin and Scc2.

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