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Folding of β-Barrel Membrane Proteins into Lipid Membranes by Site-Directed Fluorescence Spectroscopy

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Part of the book series: Methods in Molecular Biology ((MIMB,volume 2003))

Abstract

Protein–lipid interactions are important for folding and membrane insertion of integral membrane proteins that are composed either of α-helical or of β-barrel structure in their transmembrane domains. While α-helical transmembrane proteins fold co-translationally while they are synthesized by a ribosome, β-barrel transmembrane proteins (β-TMPs) fold and insert posttranslationally—in bacteria after translocation across the cytoplasmic membrane, in cell organelles of eukaryotes after import across the outer membrane of the organelle. β-TMPs can be unfolded in aqueous solutions of chaotropic denaturants like urea and spontaneously refold upon denaturant dilution in the presence of preformed lipid bilayers. This facilitates studies on lipid interactions during folding into lipid bilayers. For several β-TMPs, the kinetics of folding has been reported as strongly dependent on protein–lipid interactions. The kinetics of adsorption/insertion and folding of β-TMPs can be monitored by fluorescence spectroscopy. These fluorescence methods are even more powerful when combined with site-directed mutagenesis for the preparation of mutants of a β-TMP that are site-specifically labeled with a fluorophore or a fluorophore and fluorescence quencher or fluorescence resonance energy acceptor. Single tryptophan or single cysteine mutants of the β-TMP allow for the investigation of local protein–lipid interactions, at specific regions within the protein. To examine the structure formation of β-TMPs in a lipid environment, fluorescence spectroscopy has been used for double mutants of β-TMPs that contain a fluorescent tryptophan and a spin-label, covalently attached to a cysteine as a fluorescence quencher. The sites of mutation are selected so that the tryptophan is in close proximity to the quencher at the cysteine only when the β-TMP is folded. In a folding experiment, the evolution of fluorescence quenching as a function of time at specific sites within the protein can provide important information on the folding mechanism of the β-TMP. Here, we report protocols to examine membrane protein folding for two β-TMPs in a lipid environment, the outer membrane protein A from Escherichia coli, OmpA, and the voltage-dependent anion-selective channel, human isoform 1, hVDAC1, from mitochondria.

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Change history

  • 21 April 2020

    This chapter was inadvertently published with the expansion of the term “MNB” printed incorrectly as “N-Methyl-N-nitrosobenzamide” under section 2.5. Instead, it should have been “Methyl 4- nitrobenzenesulfonate.” This correction has been updated in the chapter.

References

  1. Kleinschmidt JH (2015) Folding of β-barrel membrane proteins in lipid bilayers - unassisted and assisted folding and insertion. Biochim Biophys Acta 1848(9):1927–1943. https://doi.org/10.1016/j.bbamem.2015.05.004

    Article  CAS  PubMed  Google Scholar 

  2. McMorran LM, Brockwell DJ, Radford SE (2014) Mechanistic studies of the biogenesis and folding of outer membrane proteins in vitro and in vivo: what have we learned to date? Arch Biochem Biophys 564:265–280. https://doi.org/10.1016/j.abb.2014.02.011

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  3. Otzen DE, Andersen KK (2013) Folding of outer membrane proteins. Arch Biochem Biophys 531(1–2):34–43. https://doi.org/10.1016/j.abb.2012.10.008

    Article  CAS  PubMed  Google Scholar 

  4. Kleinschmidt JH (2006) Folding kinetics of the outer membrane proteins OmpA and FomA into phospholipid bilayers. Chem Phys Lipids 141(1–2):30–47. https://doi.org/10.1016/j.chemphyslip.2006.02.004

    Article  CAS  PubMed  Google Scholar 

  5. Kleinschmidt JH (2003) Membrane protein folding on the example of outer membrane protein A of Escherichia coli. Cell Mol Life Sci 60(8):1547–1558. https://doi.org/10.1007/s00018-003-3170-0

    Article  CAS  PubMed  Google Scholar 

  6. Tamm LK, Arora A, Kleinschmidt JH (2001) Structure and assembly of β-barrel membrane proteins. J Biol Chem 276(35):32399–32402

    Article  CAS  PubMed  Google Scholar 

  7. Surrey T, Jähnig F (1992) Refolding and oriented insertion of a membrane protein into a lipid bilayer. Proc Natl Acad Sci U S A 89(16):7457–7461

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Pocanschi CL, Apell H-J, Puntervoll P, Høgh BT, Jensen HB, Welte W, Kleinschmidt JH (2006) The major outer membrane protein of Fusobacterium nucleatum (FomA) folds and inserts into lipid bilayers via parallel folding pathways. J Mol Biol 355:548–561

    Article  CAS  PubMed  Google Scholar 

  9. Shanmugavadivu B, Apell HJ, Meins T, Zeth K, Kleinschmidt JH (2007) Correct folding of the β-barrel of the human membrane protein VDAC requires a lipid bilayer. J Mol Biol 368:66–78

    Article  CAS  PubMed  Google Scholar 

  10. Huysmans GH, Radford SE, Brockwell DJ, Baldwin SA (2007) The N-terminal helix is a post-assembly clamp in the bacterial outer membrane protein PagP. J Mol Biol 373(3):529–540. https://doi.org/10.1016/j.jmb.2007.07.072

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  11. Surrey T, Schmid A, Jähnig F (1996) Folding and membrane insertion of the trimeric β-barrel protein OmpF. Biochemistry 35(7):2283–2288

    Article  CAS  PubMed  Google Scholar 

  12. Dewald AH, Hodges JC, Columbus L (2011) Physical determinants of β-barrel membrane protein folding in lipid vesicles. Biophys J 100(9):2131–2140. https://doi.org/10.1016/j.bpj.2011.03.025

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Burgess NK, Dao TP, Stanley AM, Fleming KG (2008) β-barrel proteins that reside in the Escherichia coli outer membrane in vivo demonstrate varied folding behavior in vitro. J Biol Chem 283(39):26748–26758. https://doi.org/10.1074/jbc.M802754200

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  14. Dornmair K, Kiefer H, Jähnig F (1990) Refolding of an integral membrane protein. OmpA of Escherichia coli. J Biol Chem 265(31):18907–18911

    CAS  PubMed  Google Scholar 

  15. Popot J-L (2014) Folding membrane proteins in vitro: a table and some comments. Arch Biochem Biophys 564:314–326. https://doi.org/10.1016/j.abb.2014.06.029

    Article  CAS  PubMed  Google Scholar 

  16. Pocanschi CL, Popot J-L, Kleinschmidt JH (2013) Folding and stability of outer membrane protein A (OmpA) from Escherichia coli in an amphipathic polymer, amphipol A8–35. Eur Biophys J 42(2–3):103–118. https://doi.org/10.1007/s00249-013-0887-z

    Article  CAS  PubMed  Google Scholar 

  17. Kleinschmidt JH, Popot JL (2014) Folding and stability of integral membrane proteins in amphipols. Arch Biochem Biophys 564C:327–343. https://doi.org/10.1016/j.abb.2014.10.013

    Article  CAS  Google Scholar 

  18. Conlan S, Bayley H (2003) Folding of a monomeric porin, OmpG, in detergent solution. Biochemistry 42(31):9453–9465

    Article  CAS  PubMed  Google Scholar 

  19. Anbazhagan V, Vijay N, Kleinschmidt JH, Marsh D (2008) Protein-lipid interactions with Fusobacterium nucleatum major outer membrane protein FomA: spin-label EPR and polarized infrared spectroscopy. Biochemistry 47(32):8414–8423. https://doi.org/10.1021/bi800750s

    Article  CAS  PubMed  Google Scholar 

  20. Anbazhagan V, Qu J, Kleinschmidt JH, Marsh D (2008) Incorporation of outer membrane protein OmpG in lipid membranes: protein-lipid interactions and β-barrel orientation. Biochemistry 47(23):6189–6198. https://doi.org/10.1021/bi800203g

    Article  CAS  PubMed  Google Scholar 

  21. Ramakrishnan M, Qu J, Pocanschi CL, Kleinschmidt JH, Marsh D (2005) Orientation of β-barrel proteins OmpA and FhuA in lipid membranes. Chain length dependence from infrared dichroism. Biochemistry 44(9):3515–3523. https://doi.org/10.1021/bi047603y

    Article  CAS  PubMed  Google Scholar 

  22. Ramakrishnan M, Pocanschi CL, Kleinschmidt JH, Marsh D (2004) Association of spin-labeled lipids with β-barrel proteins from the outer membrane of Escherichia coli. Biochemistry 43(37):11630–11636. https://doi.org/10.1021/bi048858e

    Article  CAS  PubMed  Google Scholar 

  23. Patel GJ, Kleinschmidt JH (2013) The lipid bilayer-inserted membrane protein BamA of Escherichia coli facilitates insertion and folding of outer membrane protein A from its complex with Skp. Biochemistry 52(23):3974–3986. https://doi.org/10.1021/bi400103t

    Article  CAS  PubMed  Google Scholar 

  24. Kleinschmidt JH, Tamm LK (1996) Folding intermediates of a β-barrel membrane protein. Kinetic evidence for a multi-step membrane insertion mechanism. Biochemistry 35(40):12993–13000

    Article  CAS  PubMed  Google Scholar 

  25. Surrey T, Jähnig F (1995) Kinetics of folding and membrane insertion of a β-barrel membrane protein. J Biol Chem 270(47):28199–28203

    Article  CAS  PubMed  Google Scholar 

  26. Kleinschmidt JH, Tamm LK (2002) Secondary and tertiary structure formation of the β-barrel membrane protein OmpA is synchronized and depends on membrane thickness. J Mol Biol 324:319–330

    Article  CAS  PubMed  Google Scholar 

  27. Kleinschmidt JH, Tamm LK (1999) Time-resolved distance determination by tryptophan fluorescence quenching: probing intermediates in membrane protein folding. Biochemistry 38(16):4996–5005

    Article  CAS  PubMed  Google Scholar 

  28. Huysmans GH, Radford SE, Baldwin SA, Brockwell DJ (2012) Malleability of the folding mechanism of the outer membrane protein PagP: parallel pathways and the effect of membrane elasticity. J Mol Biol 416(3):453–464. https://doi.org/10.1016/j.jmb.2011.12.039

    Article  CAS  PubMed  Google Scholar 

  29. Arora A, Rinehart D, Szabo G, Tamm LK (2000) Refolded outer membrane protein A of Escherichia coli forms ion channels with two conductance states in planar lipid bilayers. J Biol Chem 275(3):1594–1600

    Article  CAS  PubMed  Google Scholar 

  30. Kleinschmidt JH, den Blaauwen T, Driessen A, Tamm LK (1999) Outer membrane protein A of E. coli inserts and folds into lipid bilayers by a concerted mechanism. Biochemistry 38(16):5006–5016

    Article  CAS  PubMed  Google Scholar 

  31. Gupta A, Zadafiya P, Mahalakshmi R (2014) Differential contribution of tryptophans to the folding and stability of the attachment invasion locus transmembrane β-barrel from Yersinia pestis. Sci Rep 4:6508. https://doi.org/10.1038/srep06508

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  32. Hong H, Rinehart D, Tamm LK (2013) Membrane depth-dependent energetic contribution of the tryptophan side chain to the stability of integral membrane proteins. Biochemistry 52(25):4413–4421. https://doi.org/10.1021/bi400344b

    Article  CAS  PubMed  Google Scholar 

  33. Huysmans GH, Baldwin SA, Brockwell DJ, Radford SE (2010) The transition state for folding of an outer membrane protein. Proc Natl Acad Sci U S A 107(9):4099–4104. https://doi.org/10.1073/pnas.0911904107

    Article  PubMed  PubMed Central  Google Scholar 

  34. Qu J, Behrens-Kneip S, Holst O, Kleinschmidt JH (2009) Binding regions of outer membrane protein A in complexes with the periplasmic chaperone Skp. A site-directed fluorescence study. Biochemistry 48(22):4926–4936. https://doi.org/10.1021/bi9004039

    Article  CAS  PubMed  Google Scholar 

  35. Abrams FS, London E (1993) Extension of the parallax analysis of membrane penetration depth to the polar region of model membranes: use of fluorescence quenching by a spin-label attached to the phospholipid polar headgroup. Biochemistry 32(40):10826–10831

    Article  CAS  PubMed  Google Scholar 

  36. Chattopadhyay A, London E (1987) Parallax method for direct measurement of membrane penetration depth utilizing fluorescence quenching by spin-labeled phospholipids. Biochemistry 26(1):39–45

    Article  CAS  PubMed  Google Scholar 

  37. London E, Feigenson GW (1981) Fluorescence quenching in model membranes. 1. Characterization of quenching caused by a spin-labeled phospholipid. Biochemistry 20(7):1932–1938

    Article  CAS  PubMed  Google Scholar 

  38. Ladokhin AS (1997) Distribution analysis of depth-dependent fluorescence quenching in membranes: a practical guide. Methods Enzymol 278:462–473

    Article  CAS  PubMed  Google Scholar 

  39. Ladokhin AS, Wang L, Steggles AW, Holloway PW (1991) Fluorescence study of a mutant cytochrome b5 with a single tryptophan in the membrane-binding domain. Biochemistry 30(42):10200–10206

    Article  CAS  PubMed  Google Scholar 

  40. Ladokhin AS (1999) Evaluation of lipid exposure of tryptophan residues in membrane peptides and proteins. Anal Biochem 276(1):65–71

    Article  CAS  PubMed  Google Scholar 

  41. Kleinschmidt JH, Bulieris PV, Qu J, Dogterom M, den Blaauwen T (2011) Association of neighboring β–strands of outer membrane protein A in lipid bilayers revealed by site directed fluorescence quenching. J Mol Biol 407(2):316–332. https://doi.org/10.1016/j.jmb.2011.01.021

    Article  CAS  PubMed  Google Scholar 

  42. Kang G, Lopez-Pena I, Oklejas V, Gary CS, Cao W, Kim JE (2012) Förster resonance energy transfer as a probe of membrane protein folding. Biochim Biophys Acta 1818(2):154–161. https://doi.org/10.1016/j.bbamem.2011.08.029

    Article  CAS  PubMed  Google Scholar 

  43. Prilipov A, Phale PS, Van Gelder P, Rosenbusch JP, Koebnik R (1998) Coupling site-directed mutagenesis with high-level expression: large scale production of mutant porins from E. coli. FEMS Microbiol Lett 163(1):65–72

    Article  CAS  PubMed  Google Scholar 

  44. Datta DB, Arden B, Henning U (1977) Major proteins of the Escherichia coli outer cell envelope membrane as bacteriophage receptors. J Bacteriol 131(3):821–829

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  45. Freudl R, MacIntyre S, Degen M, Henning U (1988) Alterations to the signal peptide of an outer membrane protein (OmpA) of Escherichia coli K-12 can promote either the cotranslational or the posttranslational mode of processing. J Biol Chem 263(1):344–349

    CAS  PubMed  Google Scholar 

  46. Kleinschmidt JH, Wiener MC, Tamm LK (1999) Outer membrane protein A of E. coli folds into detergent micelles, but not in the presence of monomeric detergent. Protein Sci 8(10):2065–2071

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  47. Pautsch A, Vogt J, Model K, Siebold C, Schulz GE (1999) Strategy for membrane protein crystallization exemplified with OmpA and OmpX. Proteins 34(2):167–172

    Article  CAS  PubMed  Google Scholar 

  48. Maurya SR, Mahalakshmi R (2013) Modulation of human mitochondrial voltage-dependent anion channel 2 (hVDAC-2) structural stability by cysteine-assisted barrel-lipid interactions. J Biol Chem 288(35):25584–25592. https://doi.org/10.1074/jbc.M113.493692

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  49. Mager F, Gessmann D, Nussberger S, Zeth K (2011) Functional refolding and characterization of two Tom40 isoforms from human mitochondria. J Membr Biol 242(1):11–21. https://doi.org/10.1007/s00232-011-9372-8

    Article  CAS  PubMed  Google Scholar 

  50. Xia Y, Xun L (2017) Revised mechanism and improved efficiency of the QuikChange site-directed mutagenesis method. Methods Mol Biol 1498:367–374. https://doi.org/10.1007/978-1-4939-6472-7_25

    Article  CAS  PubMed  Google Scholar 

  51. Taniguchi N, Murakami H (2017) Multiple site-directed and saturation mutagenesis by the patch cloning method. Methods Mol Biol 1498:339–347. https://doi.org/10.1007/978-1-4939-6472-7_22

    Article  CAS  PubMed  Google Scholar 

  52. Laemmli UK (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227:680–685

    Article  CAS  PubMed  Google Scholar 

  53. Weber K, Osborne M (1964) The reliability of molecular weight determinations by dodecyl sulfate-polyacrylamide gel electrophoresis. J Biol Chem 244:4406–4412

    Google Scholar 

  54. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ (1951) Protein measurement with the Folin phenol reagent. J Biol Chem 193:265–275

    CAS  PubMed  Google Scholar 

  55. Heinrikson RL (1971) The selective S-methylation of sulfhydryl groups in proteins and peptides with methyl-p-nitrobenzenesulfonate. J Biol Chem 246(12):4090–4096

    CAS  PubMed  Google Scholar 

  56. Hunziker PE (1991) Cysteine modification of metallothionein. Methods Enzymol 205:399–400

    Article  CAS  PubMed  Google Scholar 

  57. Riddles PW, Blakeley RL, Zerner B (1983) Reassessment of Ellman’s reagent. Methods Enzymol 91:49–60

    Article  CAS  PubMed  Google Scholar 

  58. Rodionova NA, Tatulian SA, Surrey T, Jähnig F, Tamm LK (1995) Characterization of two membrane-bound forms of OmpA. Biochemistry 34(6):1921–1929

    Article  CAS  PubMed  Google Scholar 

  59. Marsh D, Shanmugavadivu B, Kleinschmidt JH (2006) Membrane elastic fluctuations and the insertion and tilt of β-barrel proteins. Biophys J 91:227–232

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  60. Pocanschi CL, Patel GJ, Marsh D, Kleinschmidt JH (2006) Curvature elasticity and refolding of OmpA in large unilamellar vesicles. Biophys J 91:L75–L78

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  61. Schiffrin B, Calabrese AN, Higgins AJ, Humes JR, Ashcroft AE, Kalli AC, Brockwell DJ, Radford SE (2017) Effects of periplasmic chaperones and membrane thickness on BamA-catalyzed outer-membrane protein folding. J Mol Biol 429(23):3776–3792. https://doi.org/10.1016/j.jmb.2017.09.008

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  62. Bolen EJ, Holloway PW (1990) Quenching of tryptophan fluorescence by brominated phospholipid. Biochemistry 29(41):9638–9643

    Article  CAS  PubMed  Google Scholar 

  63. Markello T, Zlotnick A, Everett J, Tennyson J, Holloway PW (1985) Determination of the topography of cytochrome b5 in lipid vesicles by fluorescence quenching. Biochemistry 24(12):2895–2901

    Article  CAS  PubMed  Google Scholar 

  64. McIntosh TJ, Holloway PW (1987) Determination of the depth of bromine atoms in bilayers formed from bromolipid probes. Biochemistry 26(6):1783–1788

    Article  CAS  PubMed  Google Scholar 

  65. Kaiser RD, London E (1998) Determination of the depth of BODIPY probes in model membranes by parallax analysis of fluorescence quenching. Biochim Biophys Acta 1375(1–2):13–22

    Article  CAS  PubMed  Google Scholar 

  66. Ladokhin AS, Holloway PW (1995) Fluorescence of membrane-bound tryptophan octyl ester: a model for studying intrinsic fluorescence of protein-membrane interactions. Biophys J 69(2):506–517

    Article  CAS  PubMed  PubMed Central  Google Scholar 

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Correspondence to Jörg H. Kleinschmidt .

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Gerlach, L., Gholami, O., Schürmann, N., Kleinschmidt, J.H. (2019). Folding of β-Barrel Membrane Proteins into Lipid Membranes by Site-Directed Fluorescence Spectroscopy. In: Kleinschmidt, J. (eds) Lipid-Protein Interactions. Methods in Molecular Biology, vol 2003. Humana, New York, NY. https://doi.org/10.1007/978-1-4939-9512-7_20

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