Chapter 1 : Co- and Posttranslational Protein Targeting to the SecYEG Translocon in

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Co- and Posttranslational Protein Targeting to the SecYEG Translocon in , Page 1 of 2

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In vitro and in vivo studies have shown that the two targeting pathways converge at the SecYEG translocon, through which the proteins are either inserted into the membrane or translocated to the periplasm. This chapter focuses more on the cotranslational pathway that is mediated by the signal recognition particle (SRP) system of as a model for gram-negative bacteria. This pathway can be divided into three main steps: (i) the targeting step, through which ribosomes translating the relevant proteins are targeted to the membrane; (ii) the intermediate step, through which the ribosomes are transferred from the targeting system to the translocon; and (iii) the insertion/translocation step, through which the translating ribosomes extrude the nascent polypeptide chain into or across the cytoplasmic membrane. SecA is the membrane peripheral ATPase subunit of the translocon. Cotranslational targeting of proteins to the membrane is mediated by the SRP system, which includes two essential proteins and an essential RNA molecule. The GTP hydrolysis step is crucial for the dissociation of SRP from its receptor after the release of the ribosome nascent chain from the targeting complex. Ribosomes translating SRP substrates are targeted to and assembled on the translocon, such that the elongating polypeptide chain is transferred directly from the tunnel in the ribosome into the translocation channel.

Citation: Bibi E. 2007. Co- and Posttranslational Protein Targeting to the SecYEG Translocon in , p 3-15. In Ehrmann M (ed), The Periplasm. ASM Press, Washington, DC. doi: 10.1128/9781555815806.ch1

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Outer Membrane Proteins
Integral Membrane Proteins
Periplasmic Space
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1. Angelini, S.,, S. Deitermann, and, H. G. Koch. 2005. FtsY, the bacterial signal-recognition particle receptor, interacts functionally and physically with the SecYEG translocon. EMBO Rep. 6:476481.
2. Avdeeva, O. N.,, A. G. Myasnikov,, P. V. Sergiev,, A. A. Bogdanov,, R. Brimacombe, and, O. A. Dontsova. 2002. Construction of the ‘minimal’ SRP that interacts with the translating ribosome but not with specific membrane receptors in Escherichia coli. FEBS Lett. 514:7073.
3. Baars, L.,, A. J. Ytterberg,, D. Drew,, S. Wagner,, C. Thilo,, K. J. van Wijk, and, J. W. de Gier. 2006. Defining the role of the E. coli chaperone SECB using comparative proteomics. J. Biol. Chem. 281:1002410034.
4. Bassford, P.,, J. Beckwith,, K. Ito,, C. Kumamoto,, S. Mizushima,, D. Oliver,, L. Randall,, T. Silhavy,, P. C. Tai, and, W. Wickner. 1991. The primary pathway of protein export in E. coli. Cell 65:367368.
5. Batey, R. T.,, R. P. Rambo,, L. Lucast,, B. Rha, and, J. A. Doudna. 2000. Crystal structure of the ri-bonucleoprotein core of the signal recognition particle. Science 287:12321239.
6. Batey, R. T.,, M. B. Sagar, and, J. A. Doudna. 2001. Structural and energetic analysis of RNA recognition by a universally conserved protein from the signal recognition particle. J. Mol. Biol. 307:229246.
7. Beck, K.,, L. F. Wu,, J. Brunner, and, M. Müller. 2000. Discrimination between SRP- and SecA/ SecB-dependent substrates involves selective recognition of nascent chains by SRP and trigger factor. EMBO J. 19:134143.
8. Beckwith, J., 1991. “Sequence-gazing?” Science 251:11611162.
9. Bernstein, H. D., 2000. The biogenesis and assembly of bacterial membrane proteins. Curr. Opin. Microbiol. 3:203209.
10. Bernstein, H. D.,, M. A. Poritz,, K. Strub,, P. J. Hoben,, S. Brenner, and, P. Walter. 1989. Model for signal sequence recognition from amino-acid sequence of 54K subunit of signal recognition particle. Nature 340:482486.
11. Bernstein, H. D.,, D. Zopf,, D. M. Freymann, and, P. Walter. 1993. Functional substitution of the signal recognition particle 54-kDa subunit by its Escherichia coli homolog. Proc. Natl. Acad. Sci. USA 90:52295233.
12. Bibi, E.,, A. A. Herskovits,, E. S. Bochkareva, and, A. Zelazny. 2001. Putative integral membrane SRP receptors. Trends Biochem. Sci. 26:1516.
13. Bovia, F., and, K. Strub. 1996. The signal recognition particle and related small cytoplasmic ribonucleo-protein particles.J. Cell Sci. 109:26012608.
14. Breukink, E.,, N. Nouwen,, A. van Raalte,, S. Mizushima,, J. Tommassen, and, B. de Kru-ijff. 1995. The C terminus of SecA is involved in both lipid binding and SecB binding. J. Biol. Chem. 270:79027907.
15. Brown, S., 1991. 4.5S RNA: does form predict function? New Biol. 3:430438.
16. Brown, S., and, M. J. Fournier. 1984. The 4.5S RNA gene of Escherichia coli is essential for cell growth. J. Mol. Biol. 178:533550.
17. Bui, N., and, K. Strub. 1999. New insights into signal recognition and elongation arrest activities of the signal recognition particle. Biol. Chem. 380:135145.
18. Buskiewicz, I.,, E. Deuerling,, S. Q. Gu,, J. Jockel,, M. V. Rodnina,, B. Bukau, and, W. Winter- meyer. 2004. Trigger factor binds to ribosome-signal-recognition particle (SRP) complexes and is excluded by binding of the SRP receptor. Proc. Natl. Acad. Sci. USA. 101:79027906.
19. Buskiewicz, I.,, A. Kubarenko,, F. Peske,, M. V. Rodnina, and, W. Wintermeyer. 2005. Domain rearrangement of SRP protein Ffh upon binding 4.5S RNA and the SRP receptor FtsY. RNA 11:947957.
20. Buskiewicz, I.,, F. Peske,, H. J. Wieden,, I. Gryczyn–ski,, M. V. Rodnina, and, W. Wintermeyer. 2005. Conformations of the signal recognition particle protein Ffh from Escherichia coli as determined by FRET. J. Mol. Biol. 351:417430.
21. de Gier, J. W.,, P. Mansournia,, Q. A. Valent,, G. J. Phillips,, J. Luirink, and, G. von Heijne. 1996. Assembly of a cytoplasmic membrane protein in Escherichia coli is dependent on the signal recognition particle. FEBS Lett. 399:307309.
22. Deitermann, S.,, G. S. Sprie, and, H. G. Koch. 2005. A dual function for SecA in the assembly of single spanning membrane proteins in Escherichia coli.J. Biol. Chem. 280:3907739085.
23. de Keyzer, J.,, E. O. van der Sluis,, R. E. Spelbrink,, N. Nijstad,, B. de Kruijff,, N. Nouwen,, C. van der Does, and, A. J. Driessen. 2005. Covalently dimerized SecA is functional in protein transloca–tion. J. Biol. Chem. 280:3525535260.
24. Dekker, C.,, B. de Kruijff, and, P. Gros. 2003. Crystal structure of SecB from Escherichia coli. J. Struct. Biol. 144:313319.
25. de Leeuw, E.,, D. Poland,, O. Mol,, I. Sinning,, C. M. ten Hagen–Jongman,, B. Oudega, and, J. Luirink. 1997. Membrane association of FtsY, the E. coli SRP receptor. FEBS Lett. 416:225229.
26. de Leeuw, E.,, K. te Kaat,, C. Moser,, G. Menest–rina,, R. Demel,, B. de Kruijff,, B. Oudega,, J. Luirink, and, I. Sinning. 2000. Anionic phos–pholipids are involved in membrane association of FtsY and stimulate its GTPase activity. EMBO J. 19:531541.
27. Deuerling, E.,, A. Schulze–Specking,, T. Tomoy–asu,, A. Mogk, and, B. Bukau. 1999. Trigger factor and DnaK cooperate in folding of newly synthesized proteins. Nature 400:693696.
28. Driessen, A. J.,, E. H. Manting, and, C. van der Does. 2001. The structural basis of protein targeting and translocation in bacteria. Nat. Struct. Biol. 8:492498.
29. Egea, P. F.,, S. O. Shan,, J. Napetschnig,, D. F. Savage,, P. Walter, and, R. M. Stroud. 2004. Substrate twinning activates the signal recognition particle and its receptor. Nature 427:215221.
30. Eichler, J., and, F. Duong. 2004. Break on through to the other side–the Sec translocon. Trends Biochem. Sci. 29:221223.
31. Eisner, G.,, M. Moser,, U. Schäfer,, K. Beck, and, M. Müller. 2006. Alternate recruitment of signal recognition particle and trigger factor to the signal sequence of a growing nascent polypeptide.J. Biol. Chem. 281:71727179.
32. Eitan, A., and, E. Bibi. 2004. The core Escherichia coli signal recognition particle receptor contains only the N and G domains of FtsY. J. Bacteriol. 186:24922494.
33. Eser, M., and, M. Ehrmann. 2003. SecA–dependent quality control of intracellular protein localization. Proc. Natl. Acad. Sci. USA 100:1323113234.
34. Fekkes, P.,, C. van der Does, and, A. J. Driessen. 1997. The molecular chaperone SecB is released from the carboxy–terminus of SecA during initiation of precursor protein translocation. EMBO J. 16:61056113.
35. Focia, P. J.,, I. V. Shepotinovskaya,, J. A. Seidler, and, D. M. Freymann. 2004. Heterodimeric GTPase core of the SRP targeting complex. Science 303:373377.
36. Freymann, D. M.,, R. J. Keenan,, R. M. Stroud, and, P. Walter. 1997. Structure of the conserved GTPase domain of the signal recognition particle. Nature 385:361364.
37. Gill, D. R., and, G. P. Salmond. 1987. The Es–cherichia coli cell division proteins FtsY, FtsE and FtsX are inner membrane–associated. Mol. Gen. Genet. 210:504508.
38. Gu, S. Q.,, F. Peske,, H. J. Wieden,, M. V. Rodnina, and, W. Wintermeyer. 2003. The signal recognition particle binds to protein L23 at the peptide exit of the Escherichia coli ribosome. RNA 9:566573.
39. Gutierrez, J. A.,, P. J. Crowley,, D. G. Cvitkovitch,, L. J. Brady,, I. R. Hamilton,, J. D. Hillman, and, A. S. Bleiweis. 1999. Streptococcus mutans ffh, a gene encoding a homologue of the 54 kDa sub–unit of the signal recognition particle, is involved in resistance to acid stress. Microbiology 145:357366.
40. Hartl, F. U.,, S. Lecker,, E. Schiebel,, J. P. Hendrick, and, W. Wickner. 1990. The binding cascade of SecB to SecA to SecY/E mediates preprotein targeting to the E. coli plasma membrane. Cell 63:269279.
41. Herskovits, A. A., and, E. Bibi. 2000. Association of Escherichia coli ribosomes with the inner membrane requires the signal recognition particle receptor but is independent of the signal recognition particle. Proc. Natl. Acad. Sci. USA 97:46214626.
42. Herskovits, A. A.,, E. S. Bochkareva, and, E. Bibi. 2000. New prospects in studying the bacterial signal recognition particle pathway. Mol. Microbiol. 38:927939.
43. Herskovits, A. A.,, E. Shimoni,, A. Minsky, and, E. Bibi. 2002. Accumulation of endoplasmic membranes and novel membrane–bound ribo–some–signal recognition particle receptor complexes in Escherichia coli. J. Cell Biol. 159:403410.
44. Houben, E. N.,, R. Zarivach,, B. Oudega, and, J. Luirink. 2005. Early encounters of a nascent membrane protein: specificity and timing of contacts inside and outside the ribosome. J. Cell Biol. 170:2735.
45. Hunt, J. F.,, S. Weinkauf,, L. Henry,, J. J. Fak,, P. McNicholas,, D. B. Oliver, and, J. Deisenhofer. 2002. Nucleotide control of interdomain interactions in the conformational reaction cycle of SecA. Science 297:20182026.
46. Jagath, J. R.,, N. B. Matassova,, E. de Leeuw,, J. M. Warnecke,, G. Lentzen,, G. M. V. Rodnina,, J. Luirink, and, W. Wintermeyer. 2001. Important role of the tetraloop region of 4.5S RNA in SRP binding to its receptor FtsY. RNA 7:293301.
47. Jagath, J. R.,, M. V. Rodnina, and, W. Wintermeyer. 2000. Conformational changes in the bacterial SRP receptor FtsY upon binding of guanine nucleotides and SRP. J. Mol. Biol. 295:745753.
48. Jensen, C. G., and, S. Pedersen. 1994. Concentrations of 4.5S RNA and Ffh protein in Escherichia coli: the stability of Ffh protein is dependent on the concentration of 4.5S RNA. J. Bacteriol. 176:7148 7154.
49. Jilaveanu, L. B., and, D. Oliver. 2006. SecA dimer cross–linked at its subunit interface is functional for protein translocation. J. Bacteriol. 188:335338.
50. Jilaveanu, L. B.,, C. R. Zito, and, D. Oliver. 2005. Dimeric SecA is essential for protein translocation. Proc. Natl. Acad. Sci. USA. 102:75117516.
51. Jovine, L.,, T. Hainzl,, C. Oubridge,, W. G. Scott,, J. Li,, T. K. Sixma,, A. Wonacott,, T. Skarzynski, and, Nagai, K., 2000. Crystal structure of the ffh and EF–G binding sites in the conserved domain IV of Escherichia coli 4.5S RNA. Struct. Fold. Des. 8:527540.
52. Jungnickel B., and, T. A. Rapoport. 1995. A post–targeting signal sequence recognition event in the endoplasmic reticulum membrane. Cell 82:261270.
53. Karamanou, S.,, G. Sianidis,, G. Gouridis,, C. Pozidis,, Y. Papanikolau,, E. Papanikou, and, A. Economou. 2005. Escherichia coli SecA truncated at its termini is functional and dimeric. FEBS Lett. 579:12671271.
54. Keenan, R. J.,, D. M. Freymann,, P. Walter, and, R. M. Stroud. 1998. Crystal structure of the signal sequence binding subunit of the signal recognition particle. Cell 94:181191.
55. Koch, H. G.,, T. Hengelage,, C. Neumann–Haefe–lin,, J. MacFarlane,, H. K. Hoffschulte,, K. L. Schimz,, B. Mechler, and, M. Müller. 1999. In vitro studies with purified components reveal signal recognition particle (SRP) and SecA/SecB as constituents of two independent protein–targeting pathways of Escherichia coli. Mol. Biol. Cell 10:21632173.
56. Koch, H. G., and, M. Müller. 2000. Dissecting the translocase and integrase functions of the Es– cherichia coli SecYEG translocon. J. Cell Biol. 150:689694.
57. Kurita, K.,, K. Honda,, S. Suzuma,, H. Takamatsu,, K. Nakamura, and, K. Yamane. 1996. Identification of a region of Bacillus subtilis Ffh, a homo–logue of mammalian SRP54 protein, that is essential for binding to small cytoplasmic RNA. J. Biol. Chem. 271:1314013146.
58. Kusters, R.,, G. Lentzen,, E. Eppens,, A. van Geel,, C. C. van der Weijden,, W. Wintermeyer, and, J. Luirink. 1995. The functioning of the SRP receptor FtsY in protein–targeting in E. coli is correlated with its ability to bind and hydrolyse GTP. FEBS Lett. 372:253258.
59. Lentzen, G.,, H. Moine,, C. Ehresmann,, B. Ehres–mann, and, W. Wintermeyer. 1996. Structure of 4.5S RNA in the signal recognition particle of Escherichia coli as studied by enzymatic and chemical probing. RNA 2:244253.
60. Luirink, J., and, I. Sinning. 2004. SRP–mediated protein targeting: structure and function revisited. Biochim. Biophys. Acta 1694:1735.
61. Luirink, J.,, S. High,, H. Wood,, A. Giner,, D. Toller–vey, and, B. Dobberstein. 1992. Signal–sequence recognition by an Escherichia coli ribonucleopro–tein complex. Nature 359:741743.
62. Luirink, J.,, C. M. ten Hagen–Jongman,, C. C. van der Weijden,, B. Oudega,, S. High,, B. Dobber–stein, and, R. Kusters. 1994. An alternative protein targeting pathway in Escherichia coli: studies on the role of FtsY. EMBO J. 13:22892296.
63. Luirink, J.,, G. von Heijne,, E. Houben, and, J. W. de Gier. 2005. Biogenesis of inner membrane proteins in Escherichia coli. Annu. Rev. Microbiol. 59:329355.
64. Macao, B.,, J. Luirink, and, T. Samuelsson. 1997. Ffh and FtsY in a Mycoplasma mycoides signal–recognition particle pathway: SRP RNA and M domain of Ffh are not required for stimulation of GTP–ase activity in vitro. Mol. Microbiol. 24:523534.
65. Macfarlane, J., and, M. Müller. 1995. The functional integration of a polytopic membrane protein of Es–cherichia coli is dependent on the bacterial signal–recognition particle. Eur. J. Biochem. 233:766771.
66. Miller, J. D.,, H. D. Bernstein, and, P. Walter. 1994. Interaction of E. coli Ffh/4.5S ribonucleoprotein and FtsY mimics that of mammalian signal recognition particle and its receptor. Nature 367:657659.
67. Millman, J. S., and, D. W. Andrews. 1999. A site–specific, membrane–dependent cleavage event defines the membrane binding domain of FtsY. J. Biol. Chem. 274:3322733234.
68. Montoya, G.,, C. Svensson,, J. Luirink, and, I. Sinning. 1997. Crystal structure of the NG domain from the signal–recognition particle receptor FtsY. Nature 385:365368.
69. Mori, H., and, K. Ito. 2001. The Sec protein–translo–cation pathway. Trends Microbiol. 9:494500.
70. Moser, C.,, O. Mol,, R. S. Goody, and, I. Sinning. 1997. The signal recognition particle receptor of Escherichia coli (FtsY) has a nucleotide exchange factor built into the GTPase domain. Proc. Natl. Acad. Sci. USA 94:1133911344.
71. Nakatogawa H., and, K. Ito. 2001. Secretion monitor, SecM, undergoes self–translation arrest in the cytosol. Mol. Cell 7:185192.
72. Neuhof, A.,, M. M. Rolls,, B. Jungnickel,, K. U. Kalies, and, T. A. Rapoport. 1998. Binding of signal recognition particle gives ribosome/nascent chain complexes a competitive advantage in endo–plasmic reticulum membrane interaction. Mol. Biol. Cell. 9:103115.
73. Neumann–Haefelin, C.,, U. Schäfer,, M. Müller, and, H. G. Koch. 2000. SRP–dependent co–trans–lational targeting and SecA–dependent transloca–tion analyzed as individual steps in the export of a bacterial protein. EMBO J. 19:64196426.
74. Newitt, J. A., and, H. D. Bernstein. 1998. A mutation in the Escherichia coli secY gene that produces distinct effects on inner membrane protein insertion and protein export. J. Biol. Chem. 273:1245112456.
75. Or, E.,, D. Boyd,, S. Gon,, J. Beckwith, and, T. A. Rapoport. 2005. The bacterial ATPase SecA functions as a monomer in protein translocation. J. Biol. Chem. 280:90979105.
76. Osborne, A. R.,, W. M. Clemons, Jr., and, T. A. Rapoport. 2004. A large conformational change of the translocation ATPase SecA. Proc. Natl. Acad. Sci. USA 101:1093710942.
77. Osborne, A. R.,, T. A. Rapoport, and, B. van den Berg. 2005. Protein translocation by the Sec61/ SecY channel. Annu. Rev. Cell Dev. Biol. 21:529550.
78. Paetzel, M.,, A. Karla,, N. C. Strynadka, and, R. E. Dalbey. 2002. Signal peptidases. Chem. Rev. 102:45494580.
79. Papanikou, E.,, S. Karamanou,, C. Baud,, M. Frank,, G. Sianidis,, D. Keramisanou,, C. G. Kalodimos,, A. Kuhn, and, A. Economou. 2005. Identification of the preprotein binding domain of SecA. J. Biol. Chem. 280:4320943217.
80. Park, S.,, G. Liu,, T. B. Topping,, W. H. Cover, and, L. L. Randall. 1988. Modulation of folding pathways of exported proteins by the leader sequence. Science 239:10331035.
81. Peluso, P.,, D. Herschlag,, S. Nock,, D. M. Frey– mann,, A. E. Johnson, and, P. Walter. 2000. Role of 4.5S RNA in assembly of the bacterial signal recognition particle with its receptor. Science 288:16401643.
82. Phillips, G. J., and, T. J. Silhavy. 1992. The E. coli ffh gene is necessary for viability and efficient protein export. Nature 359:744746.
83. Poritz, M.A.,, H. D. Bernstein,, K. Strub,, D. Zopf,, H. Wilhelm, and, P. Walter. 1990. An E. coli ri– bonucleoprotein containing 4.5S RNA resembles mammalian signal recognition particle. Science 250:11111117.
84. Poritz, M. A.,, H. D. Bernstein, and, P. Walter. 1991. Response to “Sequence–Gazing?” Nature 251:11611162.
85. Poritz, M. A.,, K. Strub, and, P. Walter. 1988. Human SRP RNA and E. coli 4.5S RNA contain a highly homologous structural domain. Cell 55:46.
86. Powers, T., and, P. Walter. 1995. Reciprocal stimulation of GTP hydrolysis by two directly interacting GTPases. Science 269:14221424.
87. Price, A.,, A. Economou,, F. Duong, and, W. Wick–ner. 1996. Separable ATPase and membrane insertion domains of the SecA subunit of preprotein translocase. J. Biol. Chem. 271:3158031584.
88. Prinz, A.,, C. Behrens,, T. A. Rapoport,, E. Hart–mann, and, K. U. Kalies. 2000. Evolutionarily conserved binding of ribosomes to the transloca–tion channel via the large ribosomal RNA. EMBO J. 19:19001906.
89. Qi, H.Y., and, H. D. Bernstein. 1999. SecA is required for the insertion of inner membrane proteins targeted by the Escherichia coli signal recognition particle. J. Biol. Chem. 274:89938997.
90. Raden, D., and, R. Gilmore. 1998. Signal recognition particle–dependent targeting of ribosomes to the rough endoplasmic reticulum in the absence and presence of the nascent polypeptide–associated complex. Mol. Biol. Cell. 9:117130.
91. Raine, A.,, N. Ivanova,, J. E. Wikberg, and, M. Ehrenberg. 2004. Simultaneous binding of trigger factor and signal recognition particle to the E. coli ribosome. Biochimie 86:495500.
92. Raine, A.,, R. Ullers,, M. Pavlov,, J. Luirink,, J. E. Wikberg, and, M. Ehrenberg. 2003. Targeting and insertion of heterologous membrane proteins in E. coli. Biochimie 85:659668.
93. Randall, L. L., and, S. J. Hardy. 1995. High selectivity with low specificity: how SecB has solved the paradox of chaperone binding. Trends Biochem. Sci. 20:6569.
94. Randall, L. L., and, S. J. Hardy. 2002. SecB, one small chaperone in the complex milieu of the cell. Cell Mol. Life Sci. 59:16171623.
95. Randall, L. L.,, T. B. Topping, and, J. S. Hardy. 1990. No specific recognition of leader peptide by SecB, a chaperone involved in protein export. Science 248:860863.
96. Ribes, V.,, K. Romisch,, A. Giner,, B. Dobberstein, and, D. Tollervey. 1990. E. coli 4.5S RNA is part of a ribonucleoprotein particle that has properties related to signal recognition particle. Cell 63:591600.
97. Romisch, K.,, J. Webb,, J. Herz,, S. Prehn,, R. Frank,, M. Vingron, and, B. Dobberstein. 1989. Homol– ogy of 54K protein of signal–recognition particle, docking protein and two E. coli proteins with putative GTP–binding domains. Nature 340:478482.
98. Rosendal, K. R.,, K. Wild,, G. Montoya, and, I. Sinning. 2003. Crystal structure of the complete core of archaeal signal recognition particle and implications for interdomain communication. Proc. Natl. Acad. Sci. USA 100:1470114706.
99. Samuelson, J. C.,, M. Chen,, F. Jiang,, I. Moller,, M. Wiedmann,, A. Kuhn,, G. J. Phillips, and, R. E. Dalbey. 2000. YidC mediates membrane protein insertion in bacteria. Nature 406:637641.
100. Samuelsson, T., and, M. Olsson. 1993. GTPase activity of a bacterial SRP–like complex. Nucleic Acids Res. 21:847853.
101. Samuelsson, T.,, M. Olsson,, P. M. Wikstrom, and, B. R. Johansson. 1995. The GTPase activity of the Escherichia coli Ffh protein is important for normal growth. Biochim. Biophys. Acta 1267:8391.
102. Schatz, G., and, B. Dobberstein. 1996. Common principles of protein translocation across membranes. Science 271:15191526.
103. Schierle, C. F.,, M. Berkmen,, D. Huber,, C. Ku– mamoto,, D. Boyd, and, J. Beckwith. 2003. The DsbA signal sequence directs efficient, cotransla–tional export of passenger proteins to the Escherichia coli periplasm via the signal recognition particle pathway. J. Bacteriol. 185:57065713.
104. Schlenker, O.,, A. Hendricks,, I. Sinning, and, K. Wild. 2006. The structure of the mammalian SRP receptor as prototype for the interaction of small GTPases with longin domains.J. Biol. Chem. 281:88988906.
105. Schmitz, U.,, T. L. James,, P. Lukavsky, and, P. Walter. 1999. Structure of the most conserved internal loop in SRP RNA. Nat. Struct. Biol. 6:634638.
106. Scotti, P. A.,, Q. A. Valent,, E. H. Manting,, M. L. Urbanus,, A. J. Driessen,, B. Oudega, and, J. Luirink. 1999. SecA is not required for signal recognition particle–mediated targeting and initial membrane insertion of a nascent inner membrane protein.J. Biol. Chem. 274:2988329888.
107. Seluanov, A., and, E. Bibi. 1997. FtsY, the prokary–otic signal recognition particle receptor homologue, is essential for biogenesis of membrane proteins. J. Biol. Chem. 272:20532055.
108. Shan, S. O.,, R. M. Stroud, and, P. Walter. 2004. Mechanism of association and reciprocal activation of two GTPases. PLoS Biol. 2:e320.
109. Shan, S. O., and, P. Walter. 2005. Molecular crosstalk between the nucleotide specificity determinant of the SRP GTPase and the SRP receptor. Biochemistry 44:62146222.
110. Sharma, V.,, A. Arockiasamy,, D. R. Ronning,, C. G. Savva,, A. Holzenburg,, M. Braunstein,, W. R. Jacobs, Jr., and, J. C. Sacchettini. 2003. Crystal structure of Mycobacterium tuberculosis SecA, a preprotein translocating ATPase. Proc. Natl. Acad. Sci. USA 100:22432248.
111. Shimohata, N.,, Y. Akiyama, and, K. Ito. 2005. Peculiar properties of DsbA in its export across the Escherichia coli cytoplasmic membrane.J. Bacteriol. 187:39974004.
112. Sianidis, G.,, S. Karamanou,, E. Vrontou,, K. Bou–lias,, K. Repanas,, N. Kyrpides,, A. S. Politou, and, A. Economou. 2001. Cross–talk between catalytic and regulatory elements in a DEAD motor domain is essential for SecA function. EMBO J. 20:961970.
113. Spanggord, R. J.,, F. Siu,, A. Ke, and, J. A. Doudna. 2005. RNA–mediated interaction between the peptide–binding and GTPase domains of the signal recognition particle. Nat. Struct. Mol. Biol. 12:11161122.
114. Strub, K.,, J. Moss, and, P. Walter. 1991. Binding sites of the 9– and 14–kilodalton heterodimeric protein subunit of the signal recognition particle (SRP) are contained exclusively in the Alu domain of SRP RNA and contain a sequence motif that is conserved in evolution. Mol. Cell Biol. 11:39493959.
115. Struck, J. C.,, H. Y. Toschka,, T. Specht, and, V. A. Erdman. 1988. Common structural features between eukaryotic 7SL RNAs, eubacterial 4.5S RNA and scRNA and archaebacterial 7S RNA. Nucleic Acids Res. 16:7740.
116. Tian, H.,, D. Boyd, and, J. Beckwith. 2000. A mutant hunt for defects in membrane protein assembly yields mutations affecting the bacterial signal recognition particle and Sec machinery. Proc. Natl. Acad. Sci. USA 97:47304735.
117. Topping, T. B.,, R. L. Woodbury,, D. L. Diamond,, S. J. Hardy, and, L. L. Randall. 2001. Direct demonstration that homotetrameric chaperone SecB undergoes a dynamic dimer–tetramer equilibrium. J. Biol. Chem. 276:74377441.
118. Ulbrandt, N. D.,, J. A. Newitt, and, H. D. Bernstein. 1997. The E. coli signal recognition particle is required for the insertion of a subset of inner membrane proteins. Cell 88:187196.
119. Ullers, R. S.,, E. N. Houben,, A. Raine,, C. M. ten Hagen–Jongman,, M. Ehrenberg,, J. Brunner,, B. Oudega,, N. Harms, and, J. Luirink. 2003. Interplay of signal recognition particle and trigger factor at L23 near the nascent chain exit site on the Escherichia coli ribosome. J. Cell Biol. 161:679684.
120. Ullers, R. S.,, J. Luirink,, N. Harms,, F. Schwager,, C. Georgopoulos, and, P. Genevaux. 2004. SecB is a bona fide generalized chaperone in Escherichia coli. Proc. Natl. Acad. Sci. USA 101:75837588.
121. Valent, Q. A.,, D. A. Kendall,, S. High,, R. Kusters,, B. Oudega, and, J. Luirink. 1995. Early events in preprotein recognition in E. coli: interaction of SRP and trigger factor with nascent polypeptides. EMBO J. 14:54945505.
122. Valent, Q. A.,, P. A. Scotti,, S. High,, J. W. de Gier,, G. von Heijne,, G. Lentzen,, W. Wintermeyer,, B. Oudega, and, J. Luirink. 1998. The Escherichia coli SRP and SecB targeting pathways converge at the translocon. EMBO J. 17:25042512.
123. Van den Berg, B.,, W. M. Clemons, Jr.,, I. Collinson,, Y. Modis,, E. Hartmann,, S. C. Harrison, and, T. A. Rapoport. 2004. X–ray structure of a protein–conducting channel. Nature 427:3644.
124. van der Laan, M.,, N. P. Nouwen, and, A. J. Driessen. 2005. YidC, an evolutionary conserved device for the assembly of energy–transducing membrane protein complexes. Curr. Opin. Microbiol. 8:182187.
125. Veenendaal, A. K.,, C. van der Does, and, A. J. Driessen. 2004. The protein–conducting channel SecYEG. Biochim. Biophys. Acta 1694:8195.
126. von Heijne, G., 1990. The signal peptide. J. Membr. Biol. 115:195201.
127. Vrontou, E., and, A. Economou. 2004. Structure and function of SecA, the preprotein translocase nanomotor. Biochim. Biophys. Acta 1694:6780.
128. Walter, P., and, A. E. Johnson. 1994. Signal sequence recognition and protein targeting to the endoplas–mic reticulum membrane. Annu. Rev. Cell Biol. 10:87119.
129. Wegrzyn, R. D., and, E. Deuerling. 2005. Molecular guardians for newborn proteins:ribosome–associated chaperones and their role in protein folding. Cell Mol. Life Sci. 62:27272738.
130. Wickner, W., and, R. Schekman. 2005. Protein translocation across biological membranes. Science 310:14521456.
131. Wood, H.,, J. Luirink, and, D. Tollervey. 1992. Evolutionary conserved nucleotides within the E. coli 4.5S RNA are required for association with P48 in vitro and for optimal function in vivo. Nucleic Acids Res. 20:59195925.
132. Xu, Z.,, J. D. Knafels, and, K. Yoshino. 2000. Crystal structure of the bacterial protein export chap–erone secB. Nat. Struct. Biol. 7:11721177.
133. Zelazny, A.,, A. Seluanov,, A. Cooper, and, E. Bibi. 1997. The NG domain of the prokaryotic signal recognition particle receptor, FtsY, is fully functional when fused to an unrelated integral membrane polypeptide. Proc. Natl. Acad. Sci. USA 94:60256029.
134. Zheng, N., and, L. M. Gierasch. 1997. Domain interactions in E. coli SRP:stabilization of M domain by RNA is required for effective signal sequence modulation of NG domain. Mol. Cell 1:7987.
135. Zhou, J., and, Z. Xu. 2003. Structural determinants of SecB recognition by SecA in bacterial protein translocation. Nat. Struct. Biol. 10:942947.

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