1932

Abstract

Many proteins are translocated across the endoplasmic reticulum (ER) membrane in eukaryotes or the plasma membrane in prokaryotes. These proteins use hydrophobic signal sequences or transmembrane (TM) segments to trigger their translocation through the protein-conducting Sec61/SecY channel. Substrates are first directed to the channel by cytosolic targeting factors, which use hydrophobic pockets to bind diverse signal and TM sequences. Subsequently, these hydrophobic sequences insert into the channel, docking into a groove on the outside of the lateral gate of the channel, where they also interact with lipids. Structural data and biochemical experiments have elucidated how channel partners, the ribosome in cotranslational translocation, and the eukaryotic ER chaperone BiP or the prokaryotic cytosolic SecA ATPase in posttranslational translocation move polypeptides unidirectionally across the membrane. Structures of auxiliary components of the bacterial translocon, YidC and SecD/F, provide additional insight. Taken together, these recent advances result in mechanistic models of protein translocation.

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2017-10-06
2024-06-17
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Literature Cited

  1. Akopian D, Shen K, Zhang X, Shan S-O. 2013. Signal recognition particle: an essential protein-targeting machine. Annu. Rev. Biochem. 82:693–721 [Google Scholar]
  2. Allen WJ, Corey RA, Oatley P, Sessions RB, Baldwin SA. et al. 2016. Two-way communication between SecY and SecA suggests a Brownian ratchet mechanism for protein translocation. eLife 5:6545 [Google Scholar]
  3. Ast T, Cohen G, Schuldiner M. 2013. A network of cytosolic factors targets SRP-independent proteins to the endoplasmic reticulum. Cell 152:51134–45 [Google Scholar]
  4. Bauer BW, Shemesh T, Chen Y, Rapoport TA. 2014. A “push and slide” mechanism allows sequence-insensitive translocation of secretory proteins by the SecA ATPase. Cell 157:61416–29 [Google Scholar]
  5. Beckwith J. 2013. The Sec-dependent pathway. Res. Microbiol. 164:6497–504 [Google Scholar]
  6. Bischoff L, Wickles S, Berninghausen O, van der Sluis EO, Beckmann R. 2014. Visualization of a polytopic membrane protein during SecY-mediated membrane insertion. Nat. Commun. 5:4103 [Google Scholar]
  7. Cannon KS, Or E, Clemons WMJ, Shibata Y, Rapoport TA. 2005. Disulfide bridge formation between SecY and a translocating polypeptide localizes the translocation pore to the center of SecY. J. Cell Biol. 169:2219–25 [Google Scholar]
  8. Chartron JW, Hunt KCL, Frydman J. 2016. Cotranslational signal-independent SRP preloading during membrane targeting. Nature 536:7615224–28 [Google Scholar]
  9. Cherepanova N, Shrimal S, Gilmore R. 2016. N-linked glycosylation and homeostasis of the endoplasmic reticulum. Curr. Opin. Cell Biol. 41:57–65 [Google Scholar]
  10. Collinson I, Corey RA, Allen WJ. 2015. Channel crossing: How are proteins shipped across the bacterial plasma membrane?. Philos. Trans. R. Soc. B 370:167920150025 [Google Scholar]
  11. Cross BCS, Sinning I, Luirink J, High S. 2009. Delivering proteins for export from the cytosol. Nat. Rev. Mol. Cell Biol. 10:4255–64 [Google Scholar]
  12. Dalal K, Duong F. 2009. The SecY complex forms a channel capable of ionic discrimination. EMBO Rep 10:7762–68 [Google Scholar]
  13. Dalbey RE, Kuhn A. 2015. Membrane insertases are present in all three domains of life. Structure 23:91559–60 [Google Scholar]
  14. Dalbey RE, Kuhn A, Zhu L, Kiefer D. 2014. The membrane insertase YidC. Biochim. Biophys. Acta 1843:81489–96 [Google Scholar]
  15. Do H, Falcone D, Lin J, Andrews DW, Johnson AE. 1996. The cotranslational integration of membrane proteins into the phospholipid bilayer is a multistep process. Cell 85:3369–78 [Google Scholar]
  16. Duong F, Wickner W. 1997. Distinct catalytic roles of the SecYE, SecG and SecDFyajC subunits of preprotein translocase holoenzyme. EMBO J 16:2756–68 [Google Scholar]
  17. Egea PF, Shan S-O, Napetschnig J, Savage DF, Walter P, Stroud RM. 2004. Substrate twinning activates the signal recognition particle and its receptor. Nature 427:6971215–21 [Google Scholar]
  18. Egea PF, Stroud RM. 2010. Lateral opening of a translocon upon entry of protein suggests the mechanism of insertion into membranes. PNAS 107:4017182–87 [Google Scholar]
  19. Elvekrog MM, Walter P. 2015. Dynamics of co-translational protein targeting. Curr. Opin. Chem. Biol. 29:79–86 [Google Scholar]
  20. Gafvelin G, von Heijne G. 1994. Topological “frustration” in multi-spanning E. coli inner membrane proteins. Cell 77:401–12 [Google Scholar]
  21. Gogala M, Becker T, Beatrix B, Armache JP, Barrio-Garcia C. et al. 2014. Structures of the Sec61 complex engaged in nascent peptide translocation or membrane insertion. Nature 506:7486107–10 [Google Scholar]
  22. Görlich D, Hartmann E, Prehn S, Rapoport TA. 1992. A protein of the endoplasmic reticulum involved early in polypeptide translocation. Nature 357:637347–52 [Google Scholar]
  23. Görlich D, Rapoport TA. 1993. Protein translocation into proteoliposomes reconstituted from purified components of the endoplasmic reticulum membrane. Cell 75:4615–30 [Google Scholar]
  24. Grudnik P, Bange G, Sinning I. 2009. Protein targeting by the signal recognition particle. Biol. Chem. 390:8775–82 [Google Scholar]
  25. Harris CR, Silhavy TJ. 1999. Mapping an interface of SecY (PrlA) and SecE (PrlG) by using synthetic phenotypes and in vivo cross-linking. J. Bacteriol. 181:113438–44 [Google Scholar]
  26. Hartl FU, Lecker S, Schiebel E, Hendrick JP, Wickner W. 1990. The binding cascade of SecB to SecA to SecY/E mediates preprotein targeting to the E. coli plasma membrane. Cell 63:2269–79 [Google Scholar]
  27. Hartmann E, Gorlich D, Kostka S, Otto A, Kraft R. et al. 1993. A tetrameric complex of membrane proteins in the endoplasmic reticulum. Eur. J. Biochem. 214:375–81 [Google Scholar]
  28. Heinrich SU, Mothes W, Brunner J, Rapoport TA. 2000. The Sec61p complex mediates the integration of a membrane protein by allowing lipid partitioning of the transmembrane domain. Cell 102:2233–44 [Google Scholar]
  29. Hessa T, Kim H, Bihlmaier K, Lundin C, Boekel J. et al. 2005. Recognition of transmembrane helices by the endoplasmic reticulum translocon. Nature 433:7024377–81 [Google Scholar]
  30. Huber D, Boyd D, Xia Y, Olma MH, Gerstein M, Beckwith J. 2005. Use of thioredoxin as a reporter to identify a subset of Escherichia coli signal sequences that promote signal recognition particle–dependent translocation. J. Bacteriol. 187:92983–91 [Google Scholar]
  31. Hunt JF, Weinkauf S, Henry L, Fak JJ, McNicholas P. et al. 2002. Nucleotide control of interdomain interactions in the conformational reaction cycle of SecA. Science 297:55892018–26 [Google Scholar]
  32. Janda CY, Li J, Oubridge C, Hernández H, Robinson CV, Nagai K. 2010. Recognition of a signal peptide by the signal recognition particle. Nature 465:7297507–10 [Google Scholar]
  33. Jomaa A, Boehringer D, Leibundgut M, Ban N. 2016. Structures of the E.coli translating ribosome with SRP and its receptor and with the translocon. Nat. Commun. 7:10471 [Google Scholar]
  34. Josefsson LG, Randall LL. 1981. Different exported proteins in E. coli show differences in the temporal mode of processing in vivo. Cell 25:1151–57 [Google Scholar]
  35. Junne T, Kocik L, Spiess M. 2010. The hydrophobic core of the Sec61 translocon defines the hydrophobicity threshold for membrane integration. Mol. Biol. Cell 21:101662–70 [Google Scholar]
  36. Keenan RJ, Freymann DM, Walter P, Stroud RM. 1998. Crystal structure of the signal sequence binding subunit of the signal recognition particle. Cell 94:2181–91 [Google Scholar]
  37. Klostermann E, Droste gen. Helling I, Carde J-P, Schünemann D. 2002. The thylakoid membrane protein ALB3 associates with the cpSecY-translocase in Arabidopsis thaliana. Biochem. J. 368:3777–81 [Google Scholar]
  38. Knyazev DG, Lents A, Krause E, Ollinger N, Siligan C. et al. 2013. The bacterial translocon SecYEG opens upon ribosome binding. J. Biol. Chem. 288:2517941–46 [Google Scholar]
  39. Kowarik M, Kung S, Martoglio B, Helenius A. 2002. Protein folding during cotranslational translocation in the endoplasmic reticulum. Mol. Cell 10:4769–78 [Google Scholar]
  40. Kumazaki K, Chiba S, Takemoto M, Furukawa A, Nishiyama K-I. et al. 2014. Structural basis of Sec-independent membrane protein insertion by YidC. Nature 509:7501516–20 [Google Scholar]
  41. Le Gall S, Neuhof A, Rapoport T. 2004. The endoplasmic reticulum membrane is permeable to small molecules. Mol. Biol. Cell 15:2447–55 [Google Scholar]
  42. Li L, Park E, Ling J, Ingram J, Ploegh H, Rapoport TA. 2016. Crystal structure of a substrate-engaged SecY protein-translocation channel. Nature 531:7594395–99 [Google Scholar]
  43. Li W, Schulman S, Boyd D, Erlandson K, Beckwith J, Rapoport TA. 2007. The plug domain of the SecY protein stabilizes the closed state of the translocation channel and maintains a membrane seal. Mol. Cell 26:4511–21 [Google Scholar]
  44. Liebermeister W, Rapoport TA, Heinrich R. 2001. Ratcheting in post-translational protein translocation: a mathematical model. J. Mol. Biol. 305:3643–56 [Google Scholar]
  45. Locker JK, Rose JK, Horzinek MC, Rottier PJM. 1992. Membrane assembly of the triple-spanning coronavirus M-protein: Individual transmembrane domains show preferred orientation. J. Biol. Chem. 267:3021911–18 [Google Scholar]
  46. Lycklama ANJA, Driessen AJ. 2012. The bacterial Sec-translocase: structure and mechanism. Philos. Trans. R. Soc. B 367:15921016–28 [Google Scholar]
  47. Mandon EC, Trueman SF, Gilmore R. 2013. Protein translocation across the rough endoplasmic reticulum. Cold Spring Harb. Perspect. Biol. 5:2a013342 [Google Scholar]
  48. Mateja A, Paduch M, Chang H-Y, Szydlowska A, Kossiakoff AA. et al. 2015. Structure of the Get3 targeting factor in complex with its membrane protein cargo. Science 347:62261152–55 [Google Scholar]
  49. Matlack KE, Misselwitz B, Plath K, Rapoport TA. 1999. BiP acts as a molecular ratchet during posttranslational transport of prepro-α factor across the ER membrane. Cell 97:5553–64 [Google Scholar]
  50. McKnight CJ, Briggs MS, Gierasch LM. 1989. Functional and nonfunctional LamB signal sequences can be distinguished by their biophysical properties. J. Biol. Chem. 264:2917293–97 [Google Scholar]
  51. Misselwitz B, Staeck O, Rapoport TA. 1998. J proteins catalytically activate Hsp70 molecules to trap a wide range of peptide sequences. Mol. Cell 2:5593–603 [Google Scholar]
  52. Ng DT, Brown JD, Walter P. 1996. Signal sequences specify the targeting route to the endoplasmic reticulum membrane. J. Cell Biol. 134:269–78 [Google Scholar]
  53. Nielsen H, Engelbrecht J, Brunak S, von Heijne G. 1997. Identification of prokaryotic and eukaryotic signal peptides and prediction of their cleavage sites. Protein Eng 10:11–6 [Google Scholar]
  54. Panzner S, Dreier L, Hartmann E, Kostka S, Rapoport TA. 1995. Posttranslational protein transport in yeast reconstituted with a purified complex of Sec proteins and Kar2p. Cell 81:561–70 [Google Scholar]
  55. Park E, Menetret JF, Gumbart JC, Ludtke SJ, Li W. et al. 2014. Structure of the SecY channel during initiation of protein translocation. Nature 506:7486102–6 [Google Scholar]
  56. Park E, Rapoport TA. 2011. Preserving the membrane barrier for small molecules during bacterial protein translocation. Nature 473:7346239–42 [Google Scholar]
  57. Park E, Rapoport TA. 2012. Mechanisms of Sec61/SecY-mediated protein translocation across membranes. Annu. Rev. Biophys. 41:21–40 [Google Scholar]
  58. Pfeffer S, Burbaum L, Unverdorben P, Pech M, Chen Y. et al. 2015. Structure of the native Sec61 protein-conducting channel. Nat. Commun. 6:8403 [Google Scholar]
  59. Plath K, Mothes W, Wilkinson BM, Stirling CJ, Rapoport TA. 1998. Signal sequence recognition in posttranslational protein transport across the yeast ER membrane. Cell 94:6795–807 [Google Scholar]
  60. Plath K, Rapoport TA. 2000. Spontaneous release of cytosolic proteins from posttranslational substrates before their transport into the endoplasmic reticulum. J. Cell Biol. 151:1167–78 [Google Scholar]
  61. Pogliano JA, Beckwith J. 1994. SecD and SecF facilitate protein export in Escherichia coli. EMBO J 13:554–61 [Google Scholar]
  62. Rapoport TA. 2007. Protein translocation across the eukaryotic endoplasmic reticulum and bacterial plasma membranes. Nature 450:7170663–69 [Google Scholar]
  63. Rapoport TA, Goder V, Heinrich SU, Matlack KE. 2004. Membrane-protein integration and the role of the translocation channel. Trends Cell Biol 14:10568–75 [Google Scholar]
  64. Rapoport TA, Heinrich R, Walter P, Schulmeister T. 1987. Mathematical modeling of the effects of the signal recognition particle on translation and translocation of proteins across the endoplasmic reticulum membrane. J. Mol. Biol. 195:3621–36 [Google Scholar]
  65. Rizo J, Blanco FJ, Kobe B, Bruch MD, Gierasch LM. 1993. Conformational behavior of Escherichia coli OmpA signal peptides in membrane mimetic environments. Biochemistry 32:184881–94 [Google Scholar]
  66. Robson A, Gold VAM, Hodson S, Clarke AR, Collinson I. 2009. Energy transduction in protein transport and the ATP hydrolytic cycle of SecA. PNAS 106:135111–16 [Google Scholar]
  67. Roy A, Wonderlin WF. 2003. The permeability of the endoplasmic reticulum is dynamically coupled to protein synthesis. J. Biol. Chem. 278:74397–403 [Google Scholar]
  68. Sachelaru I, Petriman NA, Kudva R, Kuhn P, Welte T. et al. 2013. YidC occupies the lateral gate of the SecYEG translocon and is sequentially displaced by a nascent membrane protein. J. Biol. Chem. 288:2316295–307 [Google Scholar]
  69. Saparov SM, Erlandson K, Cannon K, Schaletzky J, Schulman S. et al. 2007. Determining the conductance of the SecY protein translocation channel for small molecules. Mol. Cell 26:4501–9 [Google Scholar]
  70. Schibich D, Gloge F, Pöhner I, Björkholm P, Wade RC. et al. 2016. Global profiling of SRP interaction with nascent polypeptides. Nature 536:7615219–23 [Google Scholar]
  71. Schierle CF, Berkmen M, Huber D, Kumamoto C, Boyd D, Beckwith J. 2003. The DsbA signal sequence directs efficient, cotranslational export of passenger proteins to the Escherichia coli periplasm via the signal recognition particle pathway. J. Bacteriol. 185:195706–13 [Google Scholar]
  72. Scotti PA, Urbanus ML, Brunner J, de Gier JW, von Heijne G. et al. 2000. YidC, the Escherichia coli homologue of mitochondrial Oxa1p, is a component of the Sec translocase. EMBO J 19:4542–49 [Google Scholar]
  73. Seppälä S, Slusky JS, Lloris-Garcerá P, Rapp M, von Heijne G. 2010. Control of membrane protein topology by a single C-terminal residue. Science 328:59861698–700 [Google Scholar]
  74. Shao S, Hegde RS. 2011. A calmodulin-dependent translocation pathway for small secretory proteins. Cell 147:71576–88 [Google Scholar]
  75. Simon SM, Blobel G. 1991. A protein-conducting channel in the endoplasmic reticulum. Cell 65:3371–80 [Google Scholar]
  76. Tanaka Y, Sugano Y, Takemoto M, Mori T, Furukawa A. et al. 2015. Crystal structures of SecYEG in lipidic cubic phase elucidate a precise resting and a peptide-bound state. Cell Rep 13:81561–68 [Google Scholar]
  77. Tidow H, Nissen P. 2013. Structural diversity of calmodulin binding to its target sites. FEBS J 280:215551–65 [Google Scholar]
  78. Tripathi A, Mandon EC, Gimore R, Rapoport TA. 2017. Two alternative binding mechanisms connect the protein translocation Sec71/Sec72 complex with heat shock proteins. J. Biol. Chem. 292:198007–18 [Google Scholar]
  79. Tsukazaki T, Mori H, Echizen Y, Ishitani R, Fukai S. et al. 2011. Structure and function of a membrane component SecDF that enhances protein export. Nature 474:7350235–38 [Google Scholar]
  80. Tsukazaki T, Mori H, Fukai S, Ishitani R, Mori T. et al. 2008. Conformational transition of Sec machinery inferred from bacterial SecYE structures. Nature 455:7215988–91 [Google Scholar]
  81. van den Berg B, Clemons WMJ, Collinson I, Modis Y, Hartmann E. et al. 2004. X-ray structure of a protein-conducting channel. Nature 427:36–44 [Google Scholar]
  82. Voigt S, Jungnickel B, Hartmann E, Rapoport TA. 1996. Signal sequence–dependent function of the TRAM protein during early phases of protein transport across the endoplasmic reticulum membrane. J. Cell Biol. 134:125–35 [Google Scholar]
  83. von Heijne G. 1986. The distribution of positively charged residues in bacterial inner membrane proteins correlates with the trans-membrane topology. EMBO J 5:3021–27 [Google Scholar]
  84. von Heijne G. 2006. Membrane-protein topology. Nat. Rev. Mol. Cell Biol. 7:12909–18 [Google Scholar]
  85. Voorhees RM, Fernandez IS, Scheres SH, Hegde RS. 2014. Structure of the mammalian ribosome–Sec61 complex to 3.4 Å resolution. Cell 157:71632–43 [Google Scholar]
  86. Voorhees RM, Hegde RS. 2015. Structures of the scanning and engaged states of the mammalian SRP-ribosome complex. eLife 4:1485 [Google Scholar]
  87. Voorhees RM, Hegde RS. 2016a. Structure of the Sec61 channel opened by a signal sequence. Science 351:626888–91 [Google Scholar]
  88. Voorhees RM, Hegde RS. 2016b. Toward a structural understanding of co-translational protein translocation. Curr. Opin. Cell Biol. 41:91–99 [Google Scholar]
  89. Wickles S, Singharoy A, Andreani J, Seemayer S, Bischoff L. et al. 2014. A structural model of the active ribosome-bound membrane protein insertase YidC. eLife 3:e03035 [Google Scholar]
  90. Wiedmann M, Kurzchalia TV, Bielka H, Rapoport TA. 1987. Direct probing of the interaction between the signal sequence of nascent preprolactin and the signal recognition particle by specific cross-linking. J. Cell Biol. 104:2201–8 [Google Scholar]
  91. Yamamoto Y, Ohkubo T, Kohara A, Tanaka T, Tanaka T, Kikuchi M. 1990. Conformational requirement of signal sequences functioning in yeast: circular dichroism and 1H nuclear magnetic resonance studies of synthetic peptides. Biochemistry 29:388998–9006 [Google Scholar]
  92. Zhu L, Kaback HR, Dalbey RE. 2013. YidC protein, a molecular chaperone for LacY protein folding via the SecYEG protein machinery. J. Biol. Chem. 288:3928180–94 [Google Scholar]
  93. Zimmer J, Nam Y, Rapoport TA. 2008. Structure of a complex of the ATPase SecA and the protein-translocation channel. Nature 455:7215936–43 [Google Scholar]
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