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undergroundpanther (1000+ posts) Send PM | Profile | Ignore | Thu May-10-07 12:49 AM Original message |
what might the pigs in china might be dying from? |
Don C. Wiley, an expert on how the immune system responds
to viral attacks, such as the classic doomsday plagues of HIV, ebola and influenza, went missing. One of the foremost microbiologists in the United States, Wiley worked at the Howard Hughes Medical Institute at Harvard University. His body was found December 20,2001. Investigators said he got dizzy on a Memphis bridge and fell to his death in the river. Fancy That... Wiley was working on splicing Ebola and 1918 flu virus.The flu sample was taken from the body of a flu victim.Their grave was dug up to get the sample. http://www.iht.com/articles/2005/10/05/news/flu.php Here's Wiley's contribution to NAS on Ebola-Influenza. 1998 May 26 The National Academy of Sciences Biochemistry The central structural feature of the membrane fusion protein subunit from the Ebola virus glycoprotein is a long triple-stranded coiled coil Winfried Weissenhorn,* Lesley J. Calder,† Stephen A. Wharton,† John J. Skehel,† and Don C. Wiley*‡ *Laboratory of Molecular Medicine, Howard Hughes Medical Institute, The Children’s Hospital, 320 Longwood Avenue Boston, MA 02215; †National Institute for Medical Research, Mill Hill, The Ridgeway, London, NW7 1AA, United Kingdom; and ‡Department of Molecular and Cellular Biology, Howard Hughes Medical Institute, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138 Contributed by Don C. Wiley Accepted March 27, 1998. HA -- hemagglutinin Gp -- glycoprotein MoMuLV -- Moloney murine leukemia virus TM -- transmembrane Abstract The ectodomain of the Ebola virus Gp2 glycoprotein was solubilized with a trimeric, isoleucine zipper derived from GCN4 (pIIGCN4) in place of the hydrophobic fusion peptide at the N terminus. This chimeric molecule forms a trimeric, highly a-helical, and very thermostable molecule, as determined by chemical crosslinking and circular dichroism. Electron microscopy indicates that Ebola virus Gp2 folds into a rod-like structure like influenza HA2 and HIV-1 gp41, providing further evidence that viral fusion proteins from diverse families such as Orthomyxoviridae (Influenza), Retroviridae (HIV-1), and Filoviridae (Ebola) share common structural features, and suggesting a common membrane fusion mechanism. The filovirus or Ebola virus, has been linked to a number of lethal outbreaks of hemorrhagic fever. The virus genome is negative-stranded and encodes for seven structural and regulatory proteins, including a surface glycoprotein (Gp) that is synthesized as a precursor molecule and then cleaved into two subunits, Gp1 and Gp2, the latter of which is anchored in the membrane. Ebola Gp is encoded in two ORFs, which produce a secreted and a membrane-anchored form of Gp, whereas all other filovirus genomes encode only the membrane-anchored Gp. The secreted Ebola Gp dimer interacts with neutrophils through a Fc g receptor III (CD16b) and the membrane-anchored form binds to a number of target cells, including endothelial cells and liver cells, and is thought to mediate viral entry. Infection and replication in endothelial cells was proposed to contribute to the severe hemorrhagic character of the late stages of disease. Amino acid sequences with the potential to form coiled coils have been recognized adjacent to N-terminal fusion peptides in many viral Gps and similar a-helical models have been proposed for the HIV-gp41, Avian sarcoma virus, and Ebola virus transmembrane (TM) Gp subunits. The x-ray crystal structures of the low-pH induced conformation of influenza virus hemagglutinin (HA) 2 of a protease resistant fragment of HIV-1 env gp41, and of a small fragment of the Moloney murine leukemia virus (MoMuLV) TM protein revealed that the central part of all of these molecules is a similar, long, triple-stranded coiled coil, in the former two cases surrounded by an outer layer of antiparallel a-helices. This structural organization that places the membrane anchor in close proximity to the hydrophobic fusion peptide, at the same end of a long rod-shaped molecule, was proposed to facilitate the membrane fusion process and thus viral entry. Here, we report that the intact extracellular part of the Ebola virus subunit Gp2, lacking the N-terminal fusion peptide, can be expressed and solubilized by adding a trimeric zipper in-frame with the predicted coiled-coil region of Gp2. The oligomeric state of the chimeric molecule was characterized by chemical crosslinking and secondary structure analysis and showed a high a-helical content. Most strikingly, electron micrographs (EM) indicate a long rod-shaped structure similar to EM images observed of the low-pH-induced conformation of influenza virus HA2 and of fragments of HIV-1 env gp41, suggesting a similar role for Ebola Gp2 in membrane fusion. Cloning, Protein Expression, and Purification. The Ebola gp2 gene sequence encoding residues 552–650 (Zaire subtype) was amplified with synthetic oligonucleotides, and Cys-556 and Cys-609 were mutated to serines by standard PCR methods. DNA encoding GCN4 residues 250–280 with both the a and d positions of the coiled coil mutated to isoleucine (pII) was synthesized as two overlapping oligonucleotides. The DNA fragments encoding pII and Gp2 were subcloned into the expression vector pRSET (Invitrogen) and transformed into Escherichia coli cells BL21 DE3/pUBS. The DNA sequence was verified by sequencing. After induction of protein expression by isopropyl b-d-thiogalactoside (Sigma), bacterial pellets were lysed in 50 mM TrisHCl, pH 8.8/100 mM NaCl by sonication, and the supernatant was cleared by centrifugation at 40,000 rpm for 1 h. The soluble fraction was loaded onto a DEAE-Sepharose (Pharmacia) column (5 ¥ 25 cm) and protein was eluted with a 0.1–0.4 M NaCl gradient. Fractions containing pIIgp were identified by SDS/PAGE, concentrated in centriprep-30 (Amicon), and further purified by gel filtration chromatography with Superdex 200 (Pharmacia) (20 mM Tris, pH 8.8/100 mM NaCl). Chemical Crosslinking. pIIGp(552–650) (2 mg/ml) in 50 mM Hepes, pH 8.3/100 mM NaCl was crosslinked with ethyleneglycol bis(-succinimidylsuccinate) (EGS) (Pierce). The reactions were incubated for 1 h on ice at concentrations of 0.1, 0.5, 2.0, and 5.0 mM EGS and then quenched with 50 mM glycine. Crosslinked products were analyzed under reducing conditions on SDS/PAGE. Circular Dichroism. CD spectra of pIIGp(552–650) (0.15 mg/ml; 10 mM phosphate, pH 8.0/100 mM NaCl) were recorded at 20°C and 95°C by using a 1-mm cell on an AVIV 62DS spectropolarimeter and averaging five measurements. Thermodynamic stability was measured at 222 nm by monitoring the CD signal between 20°C and 95°C with a scan rate of 1° per min. The protein concentration was calculated by measuring the OD280, with an extinction coefficient of 29,910/M per cm. The percentage of a-helical content was estimated from 222 by assuming that a value of -33,000 degree cm2 dmol-1 corresponds to 100% a-helix content (27). The baseline value of222, equal to -2,500 deg cm2 dmol-1 of unfolded pIIGp2(552–650) was considered to be 0% a-helix content. |
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ashling (1000+ posts) Send PM | Profile | Ignore | Thu May-10-07 01:02 AM Response to Original message |
1. Is a double "might" the same as a double negative??? |
enquiring minds want to know :)
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mykpart (1000+ posts) Send PM | Profile | Ignore | Thu May-10-07 01:50 AM Response to Original message |
2. When I read your subject line, I thought, |
"Maybe the pigs got into the cat food."
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StarryNite (1000+ posts) Send PM | Profile | Ignore | Thu May-10-07 01:53 AM Response to Original message |
3. Oh, dear god |
What's next?
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