Name: a nanobar-supported lipid bilayer system for the study of membrane curvature sensing proteins in vitro
Uploaded: 2022-11-30T13:30:00
Description: Watch this Scientific Journal Video about A Nanobar-Supported Lipid Bilayer System for the Study of Membrane Curvature Sensing Proteins in vitro at JoVE.com

We thank Nanyang NanoFabrication Centre (N2FC) and the Centre for Disruptive Photonic Technologies (CDPT) at Nanyang Technological University (NTU) for supporting nanostructure fabrication and SEM imaging, the Protein Production Platform (PPP) at the School of Biological Sciences NTU for protein purification, and the School of Chemical and Biomedical Engineering NTU for the confocal microscope. This work is funded by the Singapore Ministry of Education (MOE) (W. Zhao, RG112/20, RG95/21, and MOE-T2EP30220-0009), the Institute for Digital Molecular Analytics and Science (IDMxS) supported by MOE funding under the Research Centres of Excellence scheme (W. Zhao), the Human Frontier Science Program Foundation (W. Zhao, RGY0088/2021), the NTU Start-up Grant (W. Zhao), School of Chemical and Biomedical Engineering NTU for the research scholarship (X. Miao), and China Scholarship Council for the research scholarship (J. Wu).

1. Cleaning of nanochip
<ol>
	<li>Place the nanochip in a 10 mL beaker with the patterned side facing up. 
	NOTE: This quartz nanochip has been fabricated via electron beam lithography as described before21. The geometry and arrangement of the nanostructure on the chip can be custom designed. The sizes of the gradient nanobars used here are 2000 nm in length, 600 nm in height, and 100 to 1000 nm in width (100 nm step-set).</li>
	<li>Carefully add 1 mL of 98% sulfur...

<ol>
	<li>McMahon, H. T., Gallop, J. L. Membrane curvature and mechanisms of dynamic cell membrane remodelling. Nature. 438 (7068), 590-596 (2005).</li>
	<li>Zhao, W. et al. Nanoscale manipulation of membrane curvature for probing endocytosis in live cells. Nature Nanotechnology. 12 (8), 750-756 (2017).</li>
	<li>Galic, M. et al. External push and internal pull forces recruit curvature-sensing N-BAR domain proteins to the plasma membrane. Nature Cell Biology. 14 (8), 874-881 (2012).</li>
	<li>Rosholm, K. R. et al. Membrane curvature regulates ligand-specific membrane sorting of GPCRs in living cells. Nature Chemical Biology. 13 (7), 724-729 (2017).</li>
	<li>Lou, H. Y. et al. Membrane curvature underlies actin reorganization in response to nanoscale surface topography. Proceedings of the National Academy of Sciences. 116 (46), 23143-23151 (2019).</li>
	<li>Cail, R. C., Shirazinejad, C. R., Drubin, D. G. Induced nanoscale membrane curvature bypasses the essential endocytic function of clathrin. Journal of Cell Biology. 221 (7), e202109013 (2022).</li>
	<li>Mu, H. et al. Patterning of oncogenic ras clustering in live cells using vertically aligned nanostructure arrays. Nano Letter. 22 (3), 1007-1016 (2022).</li>
	<li>Peter, B. J. et al. BAR domains as sensors of membrane curvature: the amphiphysin BAR structure. Science. 303 (5657), 495-499 (2004).</li>
	<li>Bigay, J., Casella, J. F., Drin, G., Mesmin, B., Antonny, B. ArfGAP1 responds to membrane curvature through the folding of a lipid packing sensor motif. The EMBO Journal. 24 (13), 2244-2253 (2005).</li>
	<li>Ebrahimkutty, M. P., Galic, M. Receptor-free signaling at curved cellular membranes. Bioessays. 41 (10), e1900068 (2019).</li>
	<li>Bhatia, V. K. et al. Amphipathic motifs in BAR domains are essential for membrane curvature sensing. The EMBO Journal. 28 (21), 3303-3314 (2009).</li>
	<li>Larsen, J., Hatzakis, N. S., Stamou, D. Observation of inhomogeneity in the lipid composition of individual nanoscale liposomes. Journal of the American Chemical Society. 133 (28), 10685-10687 (2011).</li>
	<li>Prevost, C. et al. IRSp53 senses negative membrane curvature and phase separates along membrane tubules. Nature Communications. 6, 8529 (2015).</li>
	<li>Simunovic, M. et al. How curvature-generating proteins build scaffolds on membrane nanotubes. Proceedings of the National Academy of Sciences. 113 (40), 11226-11231 (2016).</li>
	<li>Holkar, S. S., Kamerkar, S. C., Pucadyil, T. J. Spatial control of epsin-induced clathrin assembly by membrane curvature. Journal of Biological Chemistry. 290 (23), 14267-14276 (2015).</li>
	<li>Dar, S., Kamerkar, S. C., Pucadyil, T. J. Use of the supported membrane tube assay system for real-time analysis of membrane fission reactions. Nature Protocols. 12 (2), 390-400 (2017).</li>
	<li>Nair, P. M., Salaita, K., Petit, R. S., Groves, J. T. Using patterned supported lipid membranes to investigate the role of receptor organization in intercellular signaling. Nature Protocols. 6 (4), 523-539 (2011).</li>
	<li>Lee, I. H., Kai, H., Carlson, L. A., Groves, J. T., Hurley, J. H. Negative membrane curvature catalyzes nucleation of endosomal sorting complex required for transport (ESCRT)-III assembly. Proceedings of the National Academy of Sciences. 112 (52), 15892-15897 (2015).</li>
	<li>Beber, A. et al. Membrane reshaping by micrometric curvature sensitive septin filaments. Nature Communications. 10 (1), 420 (2019).</li>
	<li>Bridges, A. A., Jentzsch, M. S., Oakes, P. W., Occhipinti, P., Gladfelter, A. S. Micron-scale plasma membrane curvature is recognized by the septin cytoskeleton. Journal of Cell Biology. 213 (1), 23-32 (2016).</li>
	<li>Li, X. et al. A nanostructure platform for live-cell manipulation of membrane curvature. Nature Protocols. 14 (6), 1772-1802 (2019).</li>
	<li>Su, M. et al. Comparative study of curvature sensing mediated by F-BAR and an intrinsically disordered region of FBP17. iScience. 23 (11), 101712 (2020).</li>
	<li>Mayer, L. D., Hope, M. J., Cullis, P. R. Vesicles of variable sizes produced by a rapid extrusion procedure. Biochimica et Biophysica Acta. 858 (1), 161-168 (1986).</li>
	<li>Santoro, F. et al. Revealing the cell-material interface with nanometer resolution by focused ion beam/scanning electron microscopy. ACS Nano. 11 (8), 8320-8328 (2017).</li>
	<li>Platt, V. et al. Influence of multivalent nitrilotriacetic acid lipid-ligand affinity on the circulation half-life in mice of a liposome-attached His6-protein. Bioconjugate Chemistry. 21 (5), 892-902 (2010).</li>
	<li>Williams, D., Vicogne, J., Zaitseva, I., McLaughlin, S., Pessin, J. E. Evidence that electrostatic interactions between vesicle-associated membrane protein 2 and acidic phospholipids may modulate the fusion of transport vesicles with the plasma membrane. Molecular Biology of the Cell. 20 (23), 4910-4919 (2009).</li>
	<li>El Alaoui, F. et al. Structural organization and dynamics of FCHo2 docking on membranes. Elife. 11, e73156 (2022).</li>
	<li>Seu, K. J. et al. Effect of surface treatment on diffusion and domain formation in supported lipid bilayers. Biophysical Journal. 92 (7), 2445-2450 (2007).</li>
	<li>Hung, Y. F. et al. Amino terminal region of dengue virus NS4A cytosolic domain binds to highly curved liposomes. Viruses. 7 (7), 4119-4130 (2015).</li>
	<li>Hatzakis, N. S. et al. How curved membranes recruit amphipathic helices and protein anchoring motifs. Nature Chemical Biology. 5 (11), 835-841 (2009).</li>
	<li>Johnson, J. M., Ha, T., Chu, S., Boxer, S. G. Early steps of supported bilayer formation probed by single vesicle fluorescence assays. Biophysical Journal. 83 (6), 3371-3379 (2002).</li>
	<li>Jing, Y., Trefna, H., Persson, M., Kasemo, B., Svedhem, S. Formation of supported lipid bilayers on silica: relation to lipid phase transition temperature and liposome size. Soft Matter. 10 (1), 187-195 (2014).</li>
	<li>Cole, R. W., Jinadasa, T., Brown, C. M. Measuring and interpreting point spread functions to determine confocal microscope resolution and ensure quality control. Nature Protocols. 6 (12), 1929-1941 (2011).</li>
	<li>Itoh, T. et al. Dynamin and the actin cytoskeleton cooperatively regulate plasma membrane invagination by BAR and F-BAR proteins. Developmental Cell. 9 (6), 791-804 (2005).</li>
	<li>Florentsen, C. D. et al. Annexin A4 trimers are recruited by high membrane curvatures in giant plasma membrane vesicles. Soft Matter. 17 (2), 308-318 (2021).</li>
	<li>Sarkar, Y., Majumder, R., Das, S., Ray, A., Parui, P. P. Detection of curvature-radius-dependent interfacial pH/polarity for amphiphilic self-assemblies: positive versus negative curvature. Langmuir. 34 (21), 6271-6284 (2018).</li>
	<li>Raiborg, C., Stenmark, H. The ESCRT machinery in endosomal sorting of ubiquitylated membrane proteins. Nature. 458 (7237), 445-452 (2009).</li>
	<li>Alqabandi, M. et al. The ESCRT-III isoforms CHMP2A and CHMP2B display different effects on membranes upon polymerization. BMC Biology. 19 (1), 66 (2021).</li>
	<li>Leitenberger, S. M., Reister-Gottfried, E., Seifert, U. Curvature coupling dependence of membrane protein diffusion coefficients. Langmuir. 24 (4), 1254-1261 (2008).</li>
	<li>Bozelli, J. C., Jr. et al. Membrane curvature allosterically regulates the phosphatidylinositol cycle, controlling its rate and acyl-chain composition of its lipid intermediates. Journal of Biological Chemistry. 293 (46), 17780-17791 (2018).</li>
	<li>Parthasarathy, R., Yu, C. H., Groves, J. T. Curvature-modulated phase separation in lipid bilayer membranes. Langmuir. 22 (11), 5095-5099 (2006).</li>
	<li>Yuan, F. et al. Membrane bending by protein phase separation. Proceedings of the National Academy of Sciences. 118 (11), e2017435118 (2021).</li>
	<li>London, E. Membrane structure-function insights from asymmetric lipid vesicles. Accounts of Chemical Research. 52 (8), 2382-2391 (2019).</li>
	<li>Rossetti, F. F., Textor, M., Reviakine, I. Asymmetric distribution of phosphatidyl serine in supported phospholipid bilayers on titanium dioxide. Langmuir. 22 (8), 3467-3473 (2006).</li>
	<li>Richter, R. P., Maury, N., Brisson, A. R. On the effect of the solid support on the interleaflet distribution of lipids in supported lipid bilayers. Langmuir. 21 (1), 299-304 (2005).</li>
	<li>Wacklin, H. P., Thomas, R. K. Spontaneous formation of asymmetric lipid bilayers by adsorption of vesicles. Langmuir. 23 (14), 7644-7651 (2007).</li>
	<li>Lin, W. C., Blanchette, C. D., Ratto, T. V., Longo, M. L. Lipid asymmetry in DLPC/DSPC-supported lipid bilayers: a combined AFM and fluorescence microscopy study. Biophysical Journal. 90 (1), 228-237 (2006).</li>
</ol>

The nanobar-SLB system described here offers a unique combination of the advantages in several existing in vitro assays. It efficiently reveals the preferential binding of proteins to highly curved membranes as the liposome floatation or sedimentation assay but requires much fewer samples and offers more accurately defined curvature on individual nanobars8,29. It also offers a wide range of precisely controlled curvature for simultaneous comparison as th...

Membrane curvature is a critical physical parameter of a cell that occurs in a variety of cellular processes such as morphogenesis, cell division, and cell migration1. It is widely recognized now that membrane curvature is beyond a simple result of cellular events; instead, it has emerged as an effective regulator of protein interactions and intracellular signaling. For example, several proteins involved in clathrin-mediated endocytosis were found to preferentially bind to the curved membrane, resulting in the formation of a hotspot for endocytosis2. There are many different causes of membrane deformation such as membrane pulling by the cytoskeletal forces, the presence of lipid asymmetry with different sized head groups, the existence of transmembrane proteins with conical shape, the accumulation of membrane-shaping proteins like BAR-domain proteins (named after Bin, amphiphysin, and Rvs proteins), and the insertion of amphipathic helices domain into the membrane1. Interestingly, these proteins and lipids not only deform the membrane but can also sense the membrane curvature and exhibit preferential accumulation1. Therefore, it is crucial to study whether and how membranes with different curvatures alter the distribution and dynamics of proteins and lipids attached to them and the potential impacts on the related intracellular processes.
Many techniques have been developed to analyze the interaction between curved membrane and proteins in both live cell and in vitro systems. The live cell system provides a real cell environment with rich lipid diversity and dynamic protein signaling regulation2,3,4,5,6,7. However, such a sophisticated system is difficult to study due to the uncertainties and fluctuations in the intracellular environment. Hence, the in vitro assays using an artificial membrane composed of known lipid species and purified proteins have become powerful reconstitution systems to characterize the relationship between proteins and curved membranes. Traditionally, liposomes of different diameters are generated by extrusion to detect curvature-sensitive proteins via either a co-sedimentation assay using centrifugal force or a co-flotation assay with a density gradient to avoid protein aggregation8,9. However, the curvature of the extruded liposomes is limited by the available pore size of the membrane filter used in the extruder10. Single liposome curvature (SLiC) assay has been proven to overcome this limitation, in which liposomes with different diameters are fluorescence-labeled and immobilized onto the surface so that the curvature can be marked by the fluorescent intensity11. However, strong variability in lipid composition has been observed in small vesicles, which affects the accuracy of the curvature measurement12. Tether-pulling experiments provide a more accurate measurement of the curvature on the transient tether pulled from giant unilamellar vesicles (GUVs) using an optical tweezer, where the curvature can be well controlled by the membrane tension generated13,14. This method is suitable to study either positive- or negative-curvature sensing proteins, but is constrained by the throughput of tube generation10. Supported membrane tubes (SMrT) assay affords simultaneous generation of multiple membrane tubes that are extruded from the same lipid reservoir by microfluidic flows. Nevertheless, the membrane curvature varies intrinsically along the nanotube, which compromises the accuracy of fluorescence-intensity-based curvature measurement15,16. In comparison, using small unilamellar vesicles (SUVs, diameter &#60;100 nm17) to form a supported lipid bilayer (SLB) on surfaces containing designed topographies generated a single bilayer membrane with curvatures predetermined by nanofabrication or nanomaterials in high accuracy18,19,20.
Here, we present a protocol for the formation of the SLB on fabricated nanochip surfaces with nanobar arrays and how it can be used to probe the curvature sensitivity of proteins in vitro. As shown in Figure 1, there are six essential components of the assay: A) Cleaning and assembly of the chip with a microfluidic chamber; B) Preparation of SUVs&#160;with defined lipid composition; C) Formation of the SLB on a nanochip and binding with curvature sensitive proteins; D) Imaging and characterization of the SLB and curvature sensitive proteins under fluorescence microscopy; E) Cleaning the chip for reuse; F) Image processing for quantitative analysis of protein curvature sensing ability. The detailed protocol is described step-by-step below.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Anhydrous Ethanol</td>
			<td>Sigma-Aldrich</td>
			<td>100983</td>
			<td></td>
		</tr>
		<tr>
			<td>Aluminum foil</td>
			<td>Diamond</td>
			<td>RN0879999FU</td>
			<td></td>
		</tr>
		<tr>
			<td>Amber Vial</td>
			<td>Sigma-Aldrich</td>
			<td>27115-U</td>
			<td></td>
		</tr>
		<tr>
			<td>Brain PS: L-&#945;-phosphatidylserine (Brain, Porcine) (sodium salt)</td>
			<td>Avanti Polar Lipids, Inc.</td>
			<td>840032</td>
			<td></td>
		</tr>
		<tr>
			<td>10 mL Beaker</td>
			<td>Schott-Duran</td>
			<td>SCOT211060804</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL Beaker</td>
			<td>Schott-Duran</td>
			<td>SCOT211061706</td>
			<td></td>
		</tr>
		<tr>
			<td>1000 mL Beaker</td>
			<td>Schott-Duran</td>
			<td>SCOT211065408</td>
			<td>The second container&#160;</td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>Sigma-Aldrich</td>
			<td>V800117</td>
			<td></td>
		</tr>
		<tr>
			<td>Cotton buds</td>
			<td>Watsons</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>18:1 DGS-NTA(Ni): 1,2-dioleoyl-sn-glycero-3-[(N-(5-amino-1-carboxypentyl)iminodiacetic acid)succinyl] (nickel salt)</td>
			<td>Avanti Polar Lipids, Inc.</td>
			<td>790404</td>
			<td></td>
		</tr>
		<tr>
			<td>Egg PC: L-&#945;-phosphatidylcholine (Egg, Chicken)</td>
			<td>Avanti Polar Lipids, Inc.</td>
			<td>840051</td>
			<td></td>
		</tr>
		<tr>
			<td>F-BAR</td>
			<td>Protein Production Plaftorm, School of Biological Sciences, Nanyang Technological University, Singapore</td>
			<td></td>
			<td>Proteins and peptide</td>
		</tr>
		<tr>
			<td>F-BAR+IDR</td>
			<td>Protein Production Plaftorm, School of Biological Sciences, Nanyang Technological University, Singapore</td>
			<td></td>
			<td>Proteins and peptide</td>
		</tr>
		<tr>
			<td>GFP</td>
			<td>Protein Production Plaftorm, School of Biological Sciences, Nanyang Technological University, Singapore</td>
			<td></td>
			<td>Proteins and peptide</td>
		</tr>
		<tr>
			<td>GFP-His</td>
			<td>Protein Production Plaftorm, School of Biological Sciences, Nanyang Technological University, Singapore</td>
			<td></td>
			<td>Proteins and peptide</td>
		</tr>
		<tr>
			<td>GraphPad Prism</td>
			<td>GraphPad</td>
			<td>V9.0.0</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen Peroxide, 30% (Certified ACS)</td>
			<td>Thermo Scientific</td>
			<td>H325-500</td>
			<td></td>
		</tr>
		<tr>
			<td>IDR from human FBP17</td>
			<td>Sangon Biotech (Shanghai) Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td>National Institutes of Health</td>
			<td>1.50d</td>
			<td></td>
		</tr>
		<tr>
			<td>Laser Scanning Confocal Microscopy</td>
			<td>Zeiss&#160;</td>
			<td>LSM 800 with Airyscan</td>
			<td>100x (N.A.1.4) oil objective.</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Fisher scientific</td>
			<td>10010240</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini-extuder&#160;</td>
			<td>Avanti Polar Lipids, Inc.</td>
			<td>610000-1EA</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 mL Microtubes</td>
			<td>Greiner</td>
			<td>616201</td>
			<td></td>
		</tr>
		<tr>
			<td>MATLAB</td>
			<td>Mathworks</td>
			<td>R2018b</td>
			<td></td>
		</tr>
		<tr>
			<td>Nuclepore Hydrophilic Membrane,0.1 &#956;m</td>
			<td>Whatman</td>
			<td>800309</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Bufferen Saline (PBS)</td>
			<td>Life Technologies Holdings Pte Ltd.</td>
			<td>70013</td>
			<td></td>
		</tr>
		<tr>
			<td>Polydimethylsiloxane (PDMS) Base</td>
			<td>Dow Corning Corporation</td>
			<td>SYLGARD 184</td>
			<td></td>
		</tr>
		<tr>
			<td>Polydimethylsiloxane (PDMS) Crosslinker</td>
			<td>Dow Corning Corporation</td>
			<td>SYLGARD 184</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasma Cleaner</td>
			<td>HARRICK PLASMA</td>
			<td>PDC-002-HP</td>
			<td></td>
		</tr>
		<tr>
			<td>Quartz Nanochip</td>
			<td>Donghai County Alfa Quartz Products CO., LTD</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Hydroxide&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>795429</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfuric acid</td>
			<td>Sigma-Aldrich</td>
			<td>258105</td>
			<td></td>
		</tr>
		<tr>
			<td>Texas Red DHPE: Texas Red 1,2-Dihexadecanoyl-sn-Glycero-3-Phosphoethanolamine, Triethylammonium Salt</td>
			<td>Life Technologies Holdings Pte Ltd.</td>
			<td>T1395MP</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezer</td>
			<td>Gooi</td>
			<td>PDC-002-HP</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic Cleaners</td>
			<td>Elma</td>
			<td>D-78224</td>
			<td></td>
		</tr>
		<tr>
			<td>Voterx</td>
			<td>Scientific Industries</td>
			<td>G560E</td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum Desiccator</td>
			<td>NUCERITE</td>
			<td>5312</td>
			<td></td>
		</tr>
		<tr>
			<td>Water Bath</td>
			<td>Julabo</td>
			<td>TW8</td>
			<td></td>
		</tr>
	</tbody>
</table>

a nanobar-supported lipid bilayer system for the study of membrane curvature sensing proteins in vitro

Membrane curvature plays important roles&#160;in various essential processes of cells, such as cell migration, cell division, and vesicle trafficking. It is not only passively generated by cellular activities, but also actively regulates protein interactions and is involved in many intracellular signaling. Thus, it is of great value to examine the role of membrane curvature in regulating the distribution and dynamics of proteins and lipids. Recently, many techniques have been developed to study the relationship between the curved membrane and protein in vitro. Compared to traditional techniques, the newly developed nanobar-supported lipid bilayer (SLB) offers both high-throughput and better accuracy in membrane curvature generation by forming a continuous lipid bilayer on patterned arrays of nanobars with a pre-defined membrane curvature and local flat control. Both the lipid fluidity and protein sensitivity to curved membranes can be quantitatively characterized using fluorescence microscopy imaging. Here, a detailed procedure on how to form a SLB on fabricated glass surfaces containing nanobar arrays&#160;and the characterization of curvature-sensitive proteins on such SLB are introduced. In addition, protocols for nanochip reusing and image processing are covered. Beyond the nanobar-SLB, this protocol is readily applicable to all types of nanostructured glass chips for curvature sensing studies.

Nanobar design is recommended for probing positive curvature sensing proteins, which contains a half circle at each end with curvature defined by the nanobar width and one flat/zero curvature control locally at the center (Figure 2A,B). Successful formation of the SLB on nanobars results in evenly distributed lipid marker signals across the entire nanobar surface as shown in Figure 2C. Signals from multiple nanobars can be combined by averaging ...

Watch this Scientific Journal Video about A Nanobar-Supported Lipid Bilayer System for the Study of Membrane Curvature Sensing Proteins in vitro at JoVE.com

A Nanobar-Supported Lipid Bilayer System for the Study of Membrane Curvature Sensing Proteins in vitro

Here, a nanobar-supported lipid bilayer system is developed to provide a synthetic membrane with a defined curvature that enables the characterization of proteins with curvature sensing ability in vitro.

A Nanobar-Supported Lipid Bilayer System for the Study of Membrane Curvature Sensing Proteins in vitro

Membrane curvature plays important roles&#160;in various essential processes of cells, such as cell migration, cell division, and vesicle trafficking. It ...

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