Palmitoylation of SARS-CoV S protein is necessary for partitioning into detergent-resistant membranes and cell-cell fusion but not interaction with M protein

Corrin E McBride, Carolyn E Machamer, Corrin E McBride, Carolyn E Machamer

Abstract

Coronaviruses are enveloped RNA viruses that generally cause mild disease in humans. However, the recently emerged coronavirus that caused severe acute respiratory syndrome (SARS-CoV) is the most pathogenic human coronavirus discovered to date. The SARS-CoV spike (S) protein mediates virus entry by binding cellular receptors and inducing fusion between the viral envelope and the host cell membrane. Coronavirus S proteins are palmitoylated, which may affect function. Here, we created a non-palmitoylated SARS-CoV S protein by mutating all nine cytoplasmic cysteine residues. Palmitoylation of SARS-CoV S was required for partitioning into detergent-resistant membranes and for cell-cell fusion. Surprisingly, however, palmitoylation of S was not required for interaction with SARS-CoV M protein. This contrasts with the requirement for palmitoylation of mouse hepatitis virus S protein for interaction with M protein and may point to important differences in assembly and infectivity of these two coronaviruses.

Copyright 2010 Elsevier Inc. All rights reserved.

Figures

Fig. 1
Fig. 1
SARS-CoV S palmitoylation can occur in a pre-medial Golgi compartment and is a stable modification. (A) At 24 h post-transfection, HEK293T cells expressing SARS-CoV S were labeled with 35S-methionine/cysteine or 3H-palmitic acid for 30 min. After lysis, S protein was immunoprecipitated, denatured, digested with endo H, separated by SDS–PAGE and imaged by fluorography. (B) At 24 h post-transfection, HEK293T cells expressing SARS-CoV S were labeled with 35S-methionine/cysteine or 3H-palmitic acid for 30 min and chased for 0, 40, 80 or 120 min. After lysis, S protein was immunoprecipitated, separated by SDS–PAGE and analyzed by fluorography for 24 h (35S) or for 1 wk (3H).
Fig. 2
Fig. 2
SARS-CoV S lacking all cytoplasmic cysteines is not palmitoylated. (A) Cytoplasmic tail sequence of SARS-CoV S and a mutant lacking all 9 cytoplasmic cysteines (SARS-CoV SPN). (B) At 24 h post-transfection, HEK293T cells expressing SARS-CoV S or SPN were labeled with 35S-methionine/cysteine or 3H-palmitic acid for 30 min. After lysis, S protein was immunoprecipitated, separated by SDS–PAGE and analyzed by fluorography. Longer exposure (6 weeks) of the 3H-palmitate labeled samples confirmed the absence of palmitoylated SARS-CoV SPN.
Fig. 3
Fig. 3
SARS-CoV S and SARS-CoV SPN have similar half-lives. At 24 h post-transfection, HEK293T cells expressing SARS-CoV S (solid line) or SPN (dashed line) were labeled with 35S-methionine/cysteine for 20 min and chased for 0, 1, 2 or 3 h. After lysis, S protein was immunoprecipitated, separated by SDS–PAGE and analyzed by autoradiography. Percentage of S or SPN remaining at each time point was calculated using the amount of S or SPN at 0 h chase as 100%. The average of 3 independent experiments ± SEM is shown.
Fig. 4
Fig. 4
SARS-CoV S and SARS-CoV SPN both localize to the cell surface. (A) At 24 h post-transfection, HEK293T expressing SARS-CoV S or SPN were fixed, permeabilized and co-stained with mouse anti-SARS-CoV S and rabbit anti-golgin 160 (a Golgi marker). (B) At 24 h post-transfection, unpermeabilized HEK293T cells were stained with mouse anti-SARS-CoV S at 0 °C for 20 min to label SARS-CoV S or SPN present on the cell surface. Cells were then fixed, permeabilized and co-stained with rabbit anti-SARS-CoV S to label total S protein. (A and B) Secondary antibodies were Alexa 488-conjugated donkey anti-mouse IgG and Texas Red-conjugated donkey anti-rabbit IgG. The same field is shown in each set of images. (C) At 24 h post-transfection, SARS-CoV S or SPN present at the plasma membrane was biotinylated with a membrane-impermeable biotinylating agent. After lysis, biotinylated S proteins were recovered with streptavidin agarose and analyzed by SDS–PAGE and Western blotting with rabbit anti-SARS-CoV S. The graph shows quantification from 3 independent experiments ± SEM.
Fig. 5
Fig. 5
SARS-CoV S and SARS-CoV SPN can be retained at the Golgi by SARS-CoV M. (A) At 24 h post-transfection, HEK293T cells expressing SARS-CoV S or SPN and SARS-CoV M were fixed, permeabilized and co-stained with mouse anti-SARS-CoV and rabbit anti-SARS-CoV M. Secondary antibodies were Alexa 488-conjugated donkey anti-mouse IgG and Texas Red-conjugated donkey anti-rabbit IgG. (B) At 24 h post-transfection, HEK293T cells expressing SARS-CoV S or SARS-CoV SPN were labeled with 35S-methionine/cysteine for 20 min and chased for 0, 20 or 40 min. After lysis, S protein was immunoprecipitated, denatured, digested with endo H, separated by SDS–PAGE and analyzed by autoradiography. The average of 3 independent experiments ± SEM is shown.
Fig. 6
Fig. 6
SARS-CoV S palmitoylation is necessary for partitioning into detergent-resistant membranes. At 24 h post-transfection, detergent-resistant membranes (DRMs) were extracted from HEK293T cells expressing SARS-CoV S or SPN using cold Triton. DRMs were isolated using discontinuous density ultracentrifugation, and fractions were collected from the top. S protein was identified by Western blotting (upper and middle panels) and DRMs were identified using HRP-cholera toxin B, which binds ganglioside GM1 (bottom panel). A representative image of 3 independent experiments is shown.
Fig. 7
Fig. 7
SARS-CoV S palmitoylation is necessary for cell–cell fusion. At 48 h post-transfection, Vero cells expressing SARS-CoV S (A) or SARS-CoV SPN (B) were trypsinized then re-plated. At 24 h post-trypsinization, the number of nuclei per syncytia was counted; the average of 3 independent experiments ± SEM is shown (C).

References

    1. Baker T.L., Zheng H., Walker J., Coloff J.L., Buss J.E. Distinct rates of palmitate turnover on membrane-bound cellular and oncogenic H-ras. J. Biol. Chem. 2003;278(21):19292–19300.
    1. Bisht H., Roberts A., Vogel L., Bukreyev A., Collins P.L., Murphy B.R., Subbarao K., Moss B. Severe acute respiratory syndrome coronavirus spike protein expressed by attenuated vaccinia virus protectively immunizes mice. Proc. Natl. Acad. Sci. U. S. A. 2004;101(17):6641–6646.
    1. Bos E.C., Heijnen L., Luytjes W., Spaan W.J. Mutational analysis of the murine coronavirus spike protein: effect on cell-to-cell fusion. Virology. 1995;214(2):453–463.
    1. Boscarino J.A., Logan H.L., Lacny J.J., Gallagher T.M. Envelope protein palmitoylations are crucial for murine coronavirus assembly. J. Virol. 2008;82(6):2989–2999.
    1. Bosch B.J., de Haan C.A., Smits S.L., Rottier P.J. Spike protein assembly into the coronavirion: exploring the limits of its sequence requirements. Virology. 2005;334(2):306–318.
    1. Brown D.A. Lipid rafts, detergent-resistant membranes, and raft targeting signals. Physiology (Bethesda) 2006;21:430–439.
    1. Cavanagh D. The coronavirus surface glycoprotein. In: Siddell S.G., editor. The Coronaviridae. Plenum Press; New York, N.Y: 1995. pp. 73–113.
    1. Chang K.W., Sheng Y., Gombold J.L. Coronavirus-induced membrane fusion requires the cysteine-rich domain in the spike protein. Virology. 2000;269(1):212–224.
    1. Corse E., Machamer C.E. Infectious bronchitis virus E protein is targeted to the Golgi complex and directs release of virus-like particles. J. Virol. 2000;74(9):4319–4326.
    1. Corse E., Machamer C.E. The cytoplasmic tail of infectious bronchitis virus E protein directs Golgi targeting. J. Virol. 2002;76(3):1273–1284.
    1. de Haan C.A., Vennema H., Rottier P.J. Assembly of the coronavirus envelope: homotypic interactions between the M proteins. J. Virol. 2000;74(11):4967–4978.
    1. DeDiego M.L., Alvarez E., Almazan F., Rejas M.T., Lamirande E., Roberts A., Shieh W.J., Zaki S.R., Subbarao K., Enjuanes L. A severe acute respiratory syndrome coronavirus that lacks the E gene is attenuated in vitro and in vivo. J. Virol. 2007;81(4):1701–1713.
    1. Delandre C., Penabaz T.R., Passarelli A.L., Chapes S.K., Clem R.J. Mutation of juxtamembrane cysteines in the tetraspanin CD81 affects palmitoylation and alters interaction with other proteins at the cell surface. Exp. Cell Res. 2009;315(11):1953–1963.
    1. Fischer F., Stegen C.F., Masters P.S., Samsonoff W.A. Analysis of constructed E gene mutants of mouse hepatitis virus confirms a pivotal role for E protein in coronavirus assembly. J. Virol. 1998;72(10):7885–7894.
    1. Gallagher T.M., Buchmeier M.J. Coronavirus spike proteins in viral entry and pathogenesis. Virology. 2001;279(2):371–374.
    1. Godeke G.J., de Haan C.A., Rossen J.W., Vennema H., Rottier P.J. Assembly of spikes into coronavirus particles is mediated by the carboxy-terminal domain of the spike protein. J. Virol. 2000;74(3):1566–1571.
    1. Grantham M.L., Wu W.H., Lalime E.N., Lorenzo M.E., Klein S.L., Pekosz A. Palmitoylation of the influenza A virus M2 protein is not required for virus replication in vitro but contributes to virus virulence. J. Virol. 2009;83(17):8655–8661.
    1. Greaves J., Chamberlain L.H. Palmitoylation-dependent protein sorting. J. Cell Biol. 2007;176(3):249–254.
    1. Herscovics A. Importance of glycosidases in mammalian glycoprotein biosynthesis. Biochim. Biophys. Acta. 1999;1473(1):96–107.
    1. Hicks S.W., Machamer C.E. The NH2-terminal domain of Golgin-160 contains both Golgi and nuclear targeting information. J. Biol. Chem. 2002;277(39):35833–35839.
    1. Hofmann H., Hattermann K., Marzi A., Gramberg T., Geier M., Krumbiegel M., Kuate S., Uberla K., Niedrig M., Pohlmann S. S protein of severe acute respiratory syndrome-associated coronavirus mediates entry into hepatoma cell lines and is targeted by neutralizing antibodies in infected patients. J. Virol. 2004;78(12):6134–6142.
    1. Hogue, B., and Machamer, C., Eds. (2008). Coronavirus Structural Proteins and Virus Assembly. Nidoviruses. Edited by S. Perlman, T. Gallagher, and E. Snijder. Washington, D.C.: ASM Press.
    1. Holsinger L.J., Shaughnessy M.A., Micko A., Pinto L.H., Lamb R.A. Analysis of the posttranslational modifications of the influenza virus M2 protein. J. Virol. 1995;69(2):1219–1225.
    1. Hsieh Y.C., Li H.C., Chen S.C., Lo S.Y. Interactions between M protein and other structural proteins of severe, acute respiratory syndrome-associated coronavirus. J. Biomed. Sci. 2008;15(6):707–717.
    1. Huang Y., Yang Z.Y., Kong W.P., Nabel G.J. Generation of synthetic severe acute respiratory syndrome coronavirus pseudoparticles: implications for assembly and vaccine production. J. Virol. 2004;78(22):12557–12565.
    1. Iwanaga T., Tsutsumi R., Noritake J., Fukata Y., Fukata M. Dynamic protein palmitoylation in cellular signaling. Prog. Lipid Res. 2009;48(3–4):117–127.
    1. Klumperman J., Locker J.K., Meijer A., Horzinek M.C., Geuze H.J., Rottier P.J. Coronavirus M proteins accumulate in the Golgi complex beyond the site of virion budding. J. Virol. 1994;68(10):6523–6534.
    1. Kuiken T., Fouchier R.A., Schutten M., Rimmelzwaan G.F., van Amerongen G., van Riel D., Laman J.D., de Jong T., van Doornum G., Lim W., Ling A.E., Chan P.K., Tam J.S., Zambon M.C., Gopal R., Drosten C., van der Werf S., Escriou N., Manuguerra J.C., Stohr K., Peiris J.S., Osterhaus A.D. Newly discovered coronavirus as the primary cause of severe acute respiratory syndrome. Lancet. 2003;362(9380):263–270.
    1. Kuo L., Masters P.S. The small envelope protein E is not essential for murine coronavirus replication. J. Virol. 2003;77(8):4597–4608.
    1. Larson H.E., Reed S.E., Tyrrell D.A. Isolation of rhinoviruses and coronaviruses from 38 colds in adults. J. Med. Virol. 1980;5(3):221–229.
    1. Liao Y., Yuan Q., Torres J., Tam J.P., Liu D.X. Biochemical and functional characterization of the membrane association and membrane permeabilizing activity of the severe acute respiratory syndrome coronavirus envelope protein. Virology. 2006;349(2):264–275.
    1. Linder M.E., Deschenes R.J. Palmitoylation: policing protein stability and traffic. Nat. Rev. Mol. Cell Biol. 2007;8(1):74–84.
    1. Liu D.X., Yuan Q., Liao Y. Coronavirus envelope protein: a small membrane protein with multiple functions. Cell. Mol. Life Sci. 2007;64(16):2043–2048.
    1. Lontok E., Corse E., Machamer C.E. Intracellular targeting signals contribute to localization of coronavirus spike proteins near the virus assembly site. J. Virol. 2004;78(11):5913–5922.
    1. Lopez L.A., Riffle A.J., Pike S.L., Gardner D., Hogue B.G. Importance of conserved cysteine residues in the coronavirus envelope protein. J. Virol. 2008;82(6):3000–3010.
    1. Machamer C.E., Youn S. The transmembrane domain of the infectious bronchitis virus E protein is required for efficient virus release. Adv. Exp. Med. Biol. 2006;581:193–198.
    1. Majeau N., Fromentin R., Savard C., Duval M., Tremblay M.J., Leclerc D. Palmitoylation of hepatitis C virus core protein is important for virion production. J. Biol. Chem. 2009;284(49):33915–33925.
    1. Marra M.A., Jones S.J., Astell C.R., Holt R.A., Brooks-Wilson A., Butterfield Y.S., Khattra J., Asano J.K., Barber S.A., Chan S.Y., Cloutier A., Coughlin S.M., Freeman D., Girn N., Griffith O.L., Leach S.R., Mayo M., McDonald H., Montgomery S.B., Pandoh P.K., Petrescu A.S., Robertson A.G., Schein J.E., Siddiqui A., Smailus D.E., Stott J.M., Yang G.S., Plummer F., Andonov A., Artsob H., Bastien N., Bernard K., Booth T.F., Bowness D., Czub M., Drebot M., Fernando L., Flick R., Garbutt M., Gray M., Grolla A., Jones S., Feldmann H., Meyers A., Kabani A., Li Y., Normand S., Stroher U., Tipples G.A., Tyler S., Vogrig R., Ward D., Watson B., Brunham R.C., Krajden M., Petric M., Skowronski D.M., Upton C., Roper R.L. The Genome sequence of the SARS-associated coronavirus. Science. 2003;300(5624):1399–1404.
    1. McBride C.E., Li J., Machamer C.E. The cytoplasmic tail of the severe acute respiratory syndrome coronavirus spike protein contains a novel endoplasmic reticulum retrieval signal that binds COPI and promotes interaction with membrane protein. J. Virol. 2007;81(5):2418–2428.
    1. McCormick P.J., Dumaresq-Doiron K., Pluviose A.S., Pichette V., Tosato G., Lefrancois S. Palmitoylation controls recycling in lysosomal sorting and trafficking. Traffic. 2008;9(11):1984–1997.
    1. Mikic I., Planey S., Zhang J., Ceballos C., Seron T., von Massenbach B., Watson R., Callaway S., McDonough P.M., Price J.H., Hunter E., Zacharias D. A live cell, image-based approach to understanding the enzymology and pharmacology of 2-bromopalmitate and palmitoylation. Meth. Enzymol. 2006;414:150–187.
    1. Mukai A., Kurisaki T., Sato S.B., Kobayashi T., Kondoh G., Hashimoto N. Dynamic clustering and dispersion of lipid rafts contribute to fusion competence of myogenic cells. Exp. Cell Res. 2009;315(17):3052–3063.
    1. Nguyen V.P., Hogue B.G. Protein interactions during coronavirus assembly. J. Virol. 1997;71(12):9278–9284.
    1. Niwa H., Yamamura K., Miyazaki J. Efficient selection for high-expression transfectants with a novel eukaryotic vector. Gene. 1991;108(2):193–199.
    1. Nozawa N., Daikoku T., Koshizuka T., Yamauchi Y., Yoshikawa T., Nishiyama Y. Subcellular localization of herpes simplex virus type 1 UL51 protein and role of palmitoylation in Golgi apparatus targeting. J. Virol. 2003;77(5):3204–3216.
    1. Ochsenbauer-Jambor C., Miller D.C., Roberts C.R., Rhee S.S., Hunter E. Palmitoylation of the Rous sarcoma virus transmembrane glycoprotein is required for protein stability and virus infectivity. J. Virol. 2001;75(23):11544–11554.
    1. Opstelten D.J., Raamsman M.J., Wolfs K., Horzinek M.C., Rottier P.J. Envelope glycoprotein interactions in coronavirus assembly. J. Cell Biol. 1995;131(2):339–349.
    1. Ortego J., Escors D., Laude H., Enjuanes L. Generation of a replication-competent, propagation-deficient virus vector based on the transmissible gastroenteritis coronavirus genome. J. Virol. 2002;76(22):11518–11529.
    1. Ortego J., Ceriani J.E., Patino C., Plana J., Enjuanes L. Absence of E protein arrests transmissible gastroenteritis coronavirus maturation in the secretory pathway. Virology. 2007;368(2):296–308.
    1. Petit C.M., Melancon J.M., Chouljenko V.N., Colgrove R., Farzan M., Knipe D.M., Kousoulas K.G. Genetic analysis of the SARS-coronavirus spike glycoprotein functional domains involved in cell-surface expression and cell-to-cell fusion. Virology. 2005;341(2):215–230.
    1. Petit C.M., Chouljenko V.N., Iyer A., Colgrove R., Farzan M., Knipe D.M., Kousoulas K.G. Palmitoylation of the cysteine-rich endodomain of the SARS-coronavirus spike glycoprotein is important for spike-mediated cell fusion. Virology. 2007;360(2):264–274.
    1. Resh M.D. Palmitoylation of ligands, receptors, and intracellular signaling molecules. Sci. STKE. 2006;2006(359):re14.
    1. Resh M.D. Use of analogs and inhibitors to study the functional significance of protein palmitoylation. Methods. 2006;40(2):191–197.
    1. Rocks O., Peyker A., Kahms M., Verveer P.J., Koerner C., Lumbierres M., Kuhlmann J., Waldmann H., Wittinghofer A., Bastiaens P.I. An acylation cycle regulates localization and activity of palmitoylated Ras isoforms. Science. 2005;307(5716):1746–1752.
    1. Rota P.A., Oberste M.S., Monroe S.S., Nix W.A., Campagnoli R., Icenogle J.P., Penaranda S., Bankamp B., Maher K., Chen M.H., Tong S., Tamin A., Lowe L., Frace M., DeRisi J.L., Chen Q., Wang D., Erdman D.D., Peret T.C., Burns C., Ksiazek T.G., Rollin P.E., Sanchez A., Liffick S., Holloway B., Limor J., McCaustland K., Olsen-Rasmussen M., Fouchier R., Gunther S., Osterhaus A.D., Drosten C., Pallansch M.A., Anderson L.J., Bellini W.J. Characterization of a novel coronavirus associated with severe acute respiratory syndrome. Science. 2003;300(5624):1394–1399.
    1. Rousso I., Mixon M.B., Chen B.K., Kim P.S. Palmitoylation of the HIV-1 envelope glycoprotein is critical for viral infectivity. Proc. Natl. Acad. Sci. U. S. A. 2000;97(25):13523–13525.
    1. Roy S., Plowman S., Rotblat B., Prior I.A., Muncke C., Grainger S., Parton R.G., Henis Y.I., Kloog Y., Hancock J.F. Individual palmitoyl residues serve distinct roles in H-ras trafficking, microlocalization, and signaling. Mol. Cell. Biol. 2005;25(15):6722–6733.
    1. Schwegmann-Wessels C., Al-Falah M., Escors D., Wang Z., Zimmer G., Deng H., Enjuanes L., Naim H.Y., Herrler G. A novel sorting signal for intracellular localization is present in the S protein of a porcine coronavirus but absent from severe acute respiratory syndrome-associated coronavirus. J. Biol. Chem. 2004;279(42):43661–43666.
    1. Shmueli A., Segal M., Sapir T., Tsutsumi R., Noritake J., Bar A., Sapoznik S., Fukata Y., Orr I., Fukata M., Reiner O. Ndel1 palmitoylation: a new mean to regulate cytoplasmic dynein activity. Embo J. 2010;29(1):107–119.
    1. Shulla A., Gallagher T. Role of spike protein endodomains in regulating coronavirus entry. J. Biol. Chem. 2009;284(47):32725–32734.
    1. Simmons G., Reeves J.D., Rennekamp A.J., Amberg S.M., Piefer A.J., Bates P. Characterization of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) spike glycoprotein-mediated viral entry. Proc. Natl. Acad. Sci. U. S. A. 2004;101(12):4240–4245.
    1. Simons K., van Meer G. Lipid sorting in epithelial cells. Biochemistry. 1988;27(17):6197–6202.
    1. Sugrue R.J., Belshe R.B., Hay A.J. Palmitoylation of the influenza A virus M2 protein. Virology. 1990;179(1):51–56.
    1. Swift A.M., Machamer C.E. A Golgi retention signal in a membrane-spanning domain of coronavirus E1 protein. J. Cell Biol. 1991;115(1):19–30.
    1. Teissier E., Pecheur E.I. Lipids as modulators of membrane fusion mediated by viral fusion proteins. Eur. Biophys. J. 2007;36(8):887–899.
    1. Thorp E.B., Boscarino J.A., Logan H.L., Goletz J.T., Gallagher T.M. Palmitoylations on murine coronavirus spike proteins are essential for virion assembly and infectivity. J. Virol. 2006;80(3):1280–1289.
    1. Tsutsumi R., Fukata Y., Fukata M. Discovery of protein-palmitoylating enzymes. Pflugers Arch. 2008;456(6):1199–1206.
    1. van Berlo M.F., van den Brink W.J., Horzinek M.C., van der Zeijst B.A. Fatty acid acylation of viral proteins in murine hepatitis virus-infected cells. Brief report. Arch. Virol. 1987;95(1–2):123–128.
    1. Van Itallie C.M., Gambling T.M., Carson J.L., Anderson J.M. Palmitoylation of claudins is required for efficient tight-junction localization. J. Cell Sci. 2005;118(Pt 7):1427–1436.
    1. Veit M., Klenk H.D., Kendal A., Rott R. The M2 protein of influenza A virus is acylated. J. Gen. Virol. 1991;72(Pt 6):1461–1465.
    1. Voss D., Kern A., Traggiai E., Eickmann M., Stadler K., Lanzavecchia A., Becker S. Characterization of severe acute respiratory syndrome coronavirus membrane protein. FEBS Lett. 2006;580(3):968–973.
    1. WHO . Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003. World Health Organization; 2003.
    1. Yan H., Xiao G., Zhang J., Hu Y., Yuan F., Cole D.K., Zheng C., Gao G.F. SARS coronavirus induces apoptosis in Vero E6 cells. J. Med. Virol. 2004;73(3):323–331.
    1. Ye R., Montalto-Morrison C., Masters P.S. Genetic analysis of determinants for spike glycoprotein assembly into murine coronavirus virions: distinct roles for charge-rich and cysteine-rich regions of the endodomain. J. Virol. 2004;78(18):9904–9917.
    1. Youn S., Collisson E.W., Machamer C.E. Contribution of trafficking signals in the cytoplasmic tail of the infectious bronchitis virus spike protein to virus infection. J. Virol. 2005;79(21):13209–13217.
    1. Yu G.Y., Lee K.J., Gao L., Lai M.M. Palmitoylation and polymerization of hepatitis C virus NS4B protein. J. Virol. 2006;80(12):6013–6023.

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