Summer Research
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Summer Research. • Crystallization of the Lysozyme • The Structure of HDV Antigen. Institute of Molecular Biology Academic Sinica R.O.C Dr. Chwan-Deng (David) Hsiao Winnie Charng (2002/7~8). Dr. Chwan-Deng (David) Hsiao .

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Summer Research

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Summer research

Summer Research

• Crystallization of the Lysozyme

• The Structure of HDV Antigen

  • Institute of Molecular Biology Academic Sinica R.O.C

  • Dr. Chwan-Deng (David) Hsiao

  • Winnie Charng (2002/7~8)


  • Summer research

    Dr. Chwan-Deng (David) Hsiao

    Crystallographic Studies of Various Biological Macromolecules1982 B.S. Dept. Chemistry, Chung-Yuan Christian Univ. 1984 M.S. Dept. Chemistry, Natl. Taiwan univ. 1993 Ph.D. Dept. Crystallography, Univ.of Pittsburgh, USA 1993-95 PDF IMB, Academia Sinica2/95-5/99 Assistant Research Fellow, IMB5/99-present Associate Research Fellow, IMB

    Recent Research: Hsc 70, HDV antigen , Phosphoglucose isomerase and Toc 34


    Summer research

    Hsc70 is a chaperonin in cytosol and is composed of three domains. Currently, the C-terminal 10-KDa fragment is crystallized. However, its functional role needs to be determined. With this structure, the lab would like to explain experimental data and elucidate a protein-protein interaction of hsc-70 system.


    Summer research

    Phosphoglucose isomerase (PGI) is a bifunctional enzyme playing a central role in glycolysis and gluconeogenesis . More interesting, the PGI isolated from pig muscle shares 90% homologous in amino acid sequences to mouse neuroleukin, a neurotrophic factor supporting the survival of the neurons. Recent data shows that murine autocrine motility factor exhibits the enzymatic properties of PGI, and 6-phosphogluconate inhibited both enzymatic activity and AMF-induced cell motility. The lab expects to answer the key questions about the structure-function of PGI and its relationship to Neuroleukin and Tumor cell Autocrine Motility Factor. 


    Summer research

    Toc 34 is a member of the outer membrane translocon complex that mediates the initial stage of protein import into chloroplasts.Toc34 is proposed to regulate the gating properties of Toc75 or regulate the recognition and presents precursor proteins. Besides, Toc34 is a GTP-binding protein. It is anchored in the outer membrane through the C-terminal hydrophobic domain and the GTP-binding domain is exposed in the cytosol. The structure information of the Toc components will provide better understanding of how the Toc complex functions to mediate precursor protein import. .


    Summer research

    •Crystallization of the Lysozyme*Introduction *Principle*Methods and Materials*Result

    •The Structure of HDV Antigen*Introduction*Principle*Materials and Methods*Result *Discussion*Future Work


    Summer research

    *IntroductionLysozyme:It hydrolyzes the β-1,4 glucosidic linkages between NAM and NAG in the cell wall of certain microorganisms.

    Crystallization of the Lysozyme


    Summer research

    Crystallization of the Lysozyme

    *PrincipleCrystallization:formation of solid crystals from a homogeneous solution.Process:(1) nucleation--the growth of a new crystal. To initiate the process, supersaturation driving force is necessary. (2) crystals grow gradually by surface interaction with the solute.


    Summer research

    A common approach is vapor diffusion: (1)sitting drop (2)hanging drop

    [ppt]drop= [ppt]reservoir/2

    [ppt]drop= [ppt]reservoir


    Summer research

    SITTING DROP

    HANGING DROP

    Crystallization of the Lysozyme


    Summer research

    *Material and MethodSolution A: 6% lys(0.1M CH3COONa) Solution B: 15% NaCl(0.1M CH3COONa) Sitting Drop: Every well 5λA+5λB, reservoir B 1ml, 25℃ Hanging Drop:Every well 1λA+1λB (in cover slips), 500λB, 25℃

    Crystallization of the Lysozyme


    Summer research

    *Results

    The next day, I found that in all wells there were lots of large clear crystals with cubic, tetragonal, hexagonal, and trigonal shapes. In addition, the crystals in the sitting drop are bigger than that in the hanging drop.

    Crystallization of the Lysozyme


    Summer research

    Hexagonal

    Crystallization of the Lysozyme


    Summer research

    •Crystallization of the Lysozyme*Introduction *Principle*Methods and Materials*Result

    •The Structure of HDV Antigen*Introduction*Principle*Materials and Methods*Result *Discussion*Future Work


    Summer research

    The Structure of HDV Antigen

    *IntroductionHDV (hepatitis D virus), a satellite virus of hepatitis B virus. The encoded delta antigen is a nuclear phosphoprotein with RNA binding activities in regions near N terminus (residue 24~50). The crystal structure from residue 12 to 60 has been solved, and now we try to find how this region binds with polynucleotides.


    Summer research

    The Structure of HDV Antigen


    Summer research

    *PrincipleIon-exchange chromatography: The charged resins interact differently with various proteins, thus separate them by charge.X-ray diffraction:The atomic planes of a crystal cause an incident beam of X-rays to interfere with one another as they leave the crystal and are detected and calculated to get the structure.


    Summer research

    *Materials and MethodsBuffer I:50mM hepes, 20% glycerol, pH 7.8 Buffer II:50mM hepes, 2M NaCl, 20% glycerol, pH 7.8 PET plasmids with Lac operon and AmpR Insert DNA corresponds to residue 14 to 59 of HDAg DNA segments from 9 to 23 nucleotides E.coli

    The Structure of HDV Antigen


    Summer research

    Transformation

    (1) 2μl DNA+100μl competent cell(2) on ice 5 min(3) 42℃ 2 min (4) on ice 30 min

    Cell culture

    (1) +1ml LB(2) 37℃ shacking 2 hr(3) Transfer to 1L LB with 1ml amp(4) 37℃ shacking 12 hr

    The Structure of HDV Antigen


    Summer research

    Get the proteins

    (1) Collect cell pellet by centrifuge at 4℃, 4Krpm 20min

    (2) Resuspend pellet in 15ml buffer I

    (3) Microfuidizer to break the cells

    (4) Centrifuge at 4℃, 25Krpm 40min

    (5) Run PC column

    (6) Wash with 0.5, 0.8M NaCl buffer(add buffer II to I)

    (7) Elute with 1.2M NaCl buffer

    The Structure of HDV Antigen


    Summer research

    Concentration

    Transfer eluted solution to Amicon concentrator 5kd cutuntil the concentration larger than 10μg/μl (OD595nm using BSA as standard protein)

    Dialysis

    Just dilute the salt NaCl

    Set screen

    (1) Add protein solution to DNA fragment (1:1)

    (2) Add 5M NaCl (1:2)

    The Structure of HDV Antigen


    Summer research

    Modify conditions

    X-ray diffraction

    The Structure of HDV Antigen


    Summer research

    *ResultI set screen I、II、III、V and found that microcrystals grew under about 11 conditions. (see the next page)

    *Discussion As what we can see that there are no obvious common features between these conditions. Maybe the most important is that the protein has the supersaturated condition which drives the protein to aggregate orderly to become crystals.


    Summer research

    The Structure of HDV Antigen


    Summer research

    *Future WorkMicrocrystals are not big enough for x-ray diffraction. The conditions I got are still needed further modifying. Besides, the N-terminal delta antigen used in the experiments are linked to His tag. Maybe cleaving this fusion protein to get pure portion of the protein that we actually want to solve is another way the lab can try to have the crystals.

    The Structure of HDV Antigen


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