Membrane proteins: The native lipid environment is essential for their final structure!
All proteins need their native environment to function properly. To a large extent proteins are influenced by factors like temperature, pH gradient and salinity of the media/plasm.
However, compared to soluble proteins, the work with membrane proteins is influenced by an additonal factor: The lipid environment of the surrounding cell membrane.
LacY: An excellent example which shows that the native lipid environment is essential for correct membrane protein structures. Normally LacY is a multi-transmembrane domain protein, but if just one phosphopeptide is missing from the membrane, its native structure breaks down. Dowan & Bogdanov (2011) removed all traces of the phosphopeptide PE (Phosphatidyl-ethanolamine) from the bacterial cell membrane (green tips). The result: One of LacY's transmembrane domains no longer inserted itself into the cell membrane.
Conclusion: All phosphopeptides must be present in the membrane to ensure 100% accuracy of the membrane protein's folding.
How does a membrane protein scientist ensure that all native lipids are present? Let us talk about SMALPs and the world of nanodiscs!
However, compared to soluble proteins, the work with membrane proteins is influenced by an additonal factor: The lipid environment of the surrounding cell membrane.
LacY: An excellent example which shows that the native lipid environment is essential for correct membrane protein structures. Normally LacY is a multi-transmembrane domain protein, but if just one phosphopeptide is missing from the membrane, its native structure breaks down. Dowan & Bogdanov (2011) removed all traces of the phosphopeptide PE (Phosphatidyl-ethanolamine) from the bacterial cell membrane (green tips). The result: One of LacY's transmembrane domains no longer inserted itself into the cell membrane.
Conclusion: All phosphopeptides must be present in the membrane to ensure 100% accuracy of the membrane protein's folding.
How does a membrane protein scientist ensure that all native lipids are present? Let us talk about SMALPs and the world of nanodiscs!
Source: Dowhan & Bogdanov (2011)
SMALP: The superior way for membrane protein stabilization!
For experienced protein scientists one thing remains clear: Working with membrane proteins can be a lot of trouble! However, there is a solution: SMA!
SMA is short for styrene maleic anhydride. It is a type of synthetic polymer with an amazing ability. It can form structures called nanodiscs from pieces of the cell membrane (see figure 2 and 3). These synthetic nanodiscs are also called SMALPs (SMA Lipid Particles).
SMA has numerous advantages over traditional detergent based approaches:
SMA is short for styrene maleic anhydride. It is a type of synthetic polymer with an amazing ability. It can form structures called nanodiscs from pieces of the cell membrane (see figure 2 and 3). These synthetic nanodiscs are also called SMALPs (SMA Lipid Particles).
SMA has numerous advantages over traditional detergent based approaches:
- Working with detergents requires a time-consuming screening process to identify the best matching detergent for your membrane protein.
- The detergent can interfere with the 3D structure of the membrane protein and potentially decrease of its functionality
What are nanodiscs?
The term nanodisc describes a small disc shaped particle, composed of phospholipids that are held together by a belt. In this specific case the belt is composed of the polyer SMA. (see figure 2).
The purpose of nanodiscs
The main reason to use nanodisc is to provide the a mobile, near identical copy of the native environment that the membrane protein experienced in the cell membrane. Giving the membrane protein such an replacement environment is important!
Normally membrane proteins have hydrophobic amino acid residues exposed on their surface. Specifically the part that comes into contact with the hydrophobic tails of the phospholipids that make up the cell membrane bilayer.
If that part comes into contact with water or another hydrophilic media the 3D structure of the membrane protein collapses and thus it loses its functionality. Figure 3 depicts such a scenario on the left.
The purpose of nanodiscs
The main reason to use nanodisc is to provide the a mobile, near identical copy of the native environment that the membrane protein experienced in the cell membrane. Giving the membrane protein such an replacement environment is important!
Normally membrane proteins have hydrophobic amino acid residues exposed on their surface. Specifically the part that comes into contact with the hydrophobic tails of the phospholipids that make up the cell membrane bilayer.
If that part comes into contact with water or another hydrophilic media the 3D structure of the membrane protein collapses and thus it loses its functionality. Figure 3 depicts such a scenario on the left.
To avoid this from happening protein scientist have traditionally used detergents that would cover up those vulnerable parts of the membrane protein. But as stated before detergents based solubilization approaches come with their own set of problems.
How does the polymer SMA create a SMALP?
Data from de Jonge et al. (2020) & Simon et al. (2018)
Creating SMALPs that stabilize your membrane proteins is surprisingly easy. The protocol is composed of only 4 key steps:
- Addition of the correct amount of SMA to your cells (~2.5% for the first time)
- Incubation at 4°C for 16 hours at 4°C, while shaking gently
- Ultracentrifugation at 4°C (100,000 x G)
- Taking control sample and subsequent protein purification
The optimal SMA concentration for a specific experiment can vary. We recommend to try a concentration of 2.5% at the beginning.
This table shows possible SMA concentration adjustments for 50 mg SMA in different volumes.
| Volume [mL] | SMA (w/v) |
|---|---|
| 12,50 | 0,4 % |
| 7,14 | 0,7 % |
| 5,00 | 1,0 % |
| 3,33 | 1,5 % |
| 2,50 | 2,0 % |
| 2,00 | 2,5 % |
| 1,67 | 3,0 % |
| 1,43 | 3,5 % |
| 1,25 | 4,0 % |
SMA Products
All SMAs are delivered as lyophilized powder.
To provide you and your lab with the highest quality of products, Cube Biotech teamed up with the world's leading manufacturer of SMA: Orbiscope, powered by Polyscope Polymers.
This collaboration allows us to obtain the best grades of SMA and be simultaneous on the forefront of new developments. Furthermore, our SMA is optimized and licensed* to ensure highest quality! The results can be seen in the table below in our SMA product collection! Of course this selection of SMALPs can bring up the question "Where to start?". For this purpose we offer our SMALP Screening Kit and our Synthetic Nanodisc Screening Kit, that incorporates all of our SMALPs and DIBMAs.
For most other SMALP related questions we recommend the corresponding FAQ section on the Orbiscope website.
This collaboration allows us to obtain the best grades of SMA and be simultaneous on the forefront of new developments. Furthermore, our SMA is optimized and licensed* to ensure highest quality! The results can be seen in the table below in our SMA product collection! Of course this selection of SMALPs can bring up the question "Where to start?". For this purpose we offer our SMALP Screening Kit and our Synthetic Nanodisc Screening Kit, that incorporates all of our SMALPs and DIBMAs.
For most other SMALP related questions we recommend the corresponding FAQ section on the Orbiscope website.
Our selection of different SMALPs covers all potential needs.
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|---|---|---|
SMALP 140 |
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SMALP 140-I |
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SMALP 200 |
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SMALP 300 |
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SMALP 502-E This product is not available for US customers. |
If you like to order SMALP 502-E, please fill out the contact sheet. |
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SMALP Screening Sets |
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| SMALP Screening Set Contains: SMALP 140 SMALP 140-I SMALP 200 SMALP 300 |
Synthetic Nanodisc Screening Set MINI Contains: SMALP 140 SMALP 140-I SMALP 200 SMALP 300 DIBMA 10 DIBMA 12 DIBMA Glucosamine DIBMA Glycerol |
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SMALP: Not just a polymer, but also a community!
The SMALP Network was formed in 2015 and is a community of scientists and companies that all work together to bring the world of membrane protein sciences to new heights!
The network's conference is held every three months. Their purpose is to present the newest achievments of membrane protein sciences and developments on synthetic polymers like SMA and DIBMA. During the COVID-19 pandemic these meetings are held online of course.
The next SMALP Conference is scheduled for September 15th, 2022
The next SMALP Conference is scheduled for September 15th, 2022
The impact of the SMALP network cannot be understated!
Since its inception in 2015, the number of scientific publications & related patents surrounding SMALPs has grown exponentionally (see figure 5). The SMALP network collects all these publications & protocols of synthetic polymers.
The SMALP network's three founding directors:
Prof. Michael Overduin
Dr. Tim Knowles
Prof. Tim Dafforn
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To summarize: Reasons for working with SMALPs instead of detergents!
Are you interested? Fill out this form to get into contact with Cube Biotech and enter the world of SMALPs!
Disclaimer
References:
- de Jonge et al. "Development of Styrene Maleic Acid Lipid Particles as a Tool for Studies of Phage-Host Interactions" (2020) J Virol 94:e01559- 20. https://doi.org/10.1128/JVI.01559-20.
- Dowhan W & Bogdanov M. Lipid-protein interactions as determinants of membrane protein structure and function. Biochem Soc Trans. 2011 Jun;39(3):767-74. doi: 10.1042/BST0390767. PMID: 21599647; PMCID: PMC3348788.
- Simon, Kailene S et al. “Membrane protein nanoparticles: the shape of things to come.” Biochemical Society transactions vol. 46,6 (2018): 1495-1504. doi:10.1042/BST20180139
- Hall, Stephen CL, et al. "An acid-compatible co-polymer for the solubilization of membranes and proteins into lipid bilayer-containing nanoparticles." Nanoscale 10.22 (2018): 10609-10619.
Disclaimer
References:
- de Jonge et al. "Development of Styrene Maleic Acid Lipid Particles as a Tool for Studies of Phage-Host Interactions" (2020) J Virol 94:e01559- 20. https://doi.org/10.1128/JVI.01559-20.
- Dowhan W & Bogdanov M. Lipid-protein interactions as determinants of membrane protein structure and function. Biochem Soc Trans. 2011 Jun;39(3):767-74. doi: 10.1042/BST0390767. PMID: 21599647; PMCID: PMC3348788.
- Simon, Kailene S et al. “Membrane protein nanoparticles: the shape of things to come.” Biochemical Society transactions vol. 46,6 (2018): 1495-1504. doi:10.1042/BST20180139
- Hall, Stephen CL, et al. "An acid-compatible co-polymer for the solubilization of membranes and proteins into lipid bilayer-containing nanoparticles." Nanoscale 10.22 (2018): 10609-10619.