Abstract
Although interactions between lipids and membrane proteins (MPs) have been considered crucially important for understanding the functions of lipids, lack of useful and convincing experimental methods has hampered the analysis of the interactions. Here, we developed a surface plasmon resonance (SPR)-based concise method for quantitative analysis of lipid-MP interactions, coating the sensor chip surface with self-assembled monolayer (SAM) with C 6 -chain. To develop this method, we used bacteriorhodopsin (bR) as an MP, and examined its interaction with various types of lipids. The merits of using C 6 -SAM-modified sensor chip are as follows: (1) alkyl-chains of SAM confer a better immobilization of MPs because of the efficient preconcentration due to hydrophobic contacts; (2) SAM provides immobilized MPs with a partial membranous environment, which is important for the stabilization of MPs; and (3) a thinner C 6 -SAM layer (1 nm) compared with MP size forces the MP to bulge outward from the SAM surface, allowing extraneously injected lipids to be accessible to the hydrophobic transmembrane regions. Actually, the amount of bR immobilized on C 6 -SAM is 10 times higher than that on a hydrophilic CM5 sensor chip, and AFM observations confirmed that bR molecules are exposed on the SAM surface. Of the lipids tested, S-TGA-1, a halobacterium-derived glycolipid, had the highest specificity to bR with a nanomolar dissociation constant. This is consistent with the reported co-crystal structure that indicates the formation of several intermolecular hydrogen bonds. Therefore, we not only reproduced the specific lipid-bR recognition, but also succeeded in its quantitative evaluation, demonstrating the validity and utility of this method.
| Original language | English |
|---|---|
| Pages (from-to) | 103-112 |
| Number of pages | 10 |
| Journal | Analytica Chimica Acta |
| Volume | 1059 |
| DOIs | |
| Publication status | Published - Jun 20 2019 |
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All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Biochemistry
- Environmental Chemistry
- Spectroscopy
Cite this
A concise method for quantitative analysis of interactions between lipids and membrane proteins. / Inada, Masataka; Kinoshita, Masanao; Sumino, Ayumi; Oiki, Shigetoshi; Matsumori, Nobuaki.
In: Analytica Chimica Acta, Vol. 1059, 20.06.2019, p. 103-112.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A concise method for quantitative analysis of interactions between lipids and membrane proteins
AU - Inada, Masataka
AU - Kinoshita, Masanao
AU - Sumino, Ayumi
AU - Oiki, Shigetoshi
AU - Matsumori, Nobuaki
PY - 2019/6/20
Y1 - 2019/6/20
N2 - Although interactions between lipids and membrane proteins (MPs) have been considered crucially important for understanding the functions of lipids, lack of useful and convincing experimental methods has hampered the analysis of the interactions. Here, we developed a surface plasmon resonance (SPR)-based concise method for quantitative analysis of lipid-MP interactions, coating the sensor chip surface with self-assembled monolayer (SAM) with C 6 -chain. To develop this method, we used bacteriorhodopsin (bR) as an MP, and examined its interaction with various types of lipids. The merits of using C 6 -SAM-modified sensor chip are as follows: (1) alkyl-chains of SAM confer a better immobilization of MPs because of the efficient preconcentration due to hydrophobic contacts; (2) SAM provides immobilized MPs with a partial membranous environment, which is important for the stabilization of MPs; and (3) a thinner C 6 -SAM layer (1 nm) compared with MP size forces the MP to bulge outward from the SAM surface, allowing extraneously injected lipids to be accessible to the hydrophobic transmembrane regions. Actually, the amount of bR immobilized on C 6 -SAM is 10 times higher than that on a hydrophilic CM5 sensor chip, and AFM observations confirmed that bR molecules are exposed on the SAM surface. Of the lipids tested, S-TGA-1, a halobacterium-derived glycolipid, had the highest specificity to bR with a nanomolar dissociation constant. This is consistent with the reported co-crystal structure that indicates the formation of several intermolecular hydrogen bonds. Therefore, we not only reproduced the specific lipid-bR recognition, but also succeeded in its quantitative evaluation, demonstrating the validity and utility of this method.
AB - Although interactions between lipids and membrane proteins (MPs) have been considered crucially important for understanding the functions of lipids, lack of useful and convincing experimental methods has hampered the analysis of the interactions. Here, we developed a surface plasmon resonance (SPR)-based concise method for quantitative analysis of lipid-MP interactions, coating the sensor chip surface with self-assembled monolayer (SAM) with C 6 -chain. To develop this method, we used bacteriorhodopsin (bR) as an MP, and examined its interaction with various types of lipids. The merits of using C 6 -SAM-modified sensor chip are as follows: (1) alkyl-chains of SAM confer a better immobilization of MPs because of the efficient preconcentration due to hydrophobic contacts; (2) SAM provides immobilized MPs with a partial membranous environment, which is important for the stabilization of MPs; and (3) a thinner C 6 -SAM layer (1 nm) compared with MP size forces the MP to bulge outward from the SAM surface, allowing extraneously injected lipids to be accessible to the hydrophobic transmembrane regions. Actually, the amount of bR immobilized on C 6 -SAM is 10 times higher than that on a hydrophilic CM5 sensor chip, and AFM observations confirmed that bR molecules are exposed on the SAM surface. Of the lipids tested, S-TGA-1, a halobacterium-derived glycolipid, had the highest specificity to bR with a nanomolar dissociation constant. This is consistent with the reported co-crystal structure that indicates the formation of several intermolecular hydrogen bonds. Therefore, we not only reproduced the specific lipid-bR recognition, but also succeeded in its quantitative evaluation, demonstrating the validity and utility of this method.
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U2 - 10.1016/j.aca.2019.01.042
DO - 10.1016/j.aca.2019.01.042
M3 - Article
VL - 1059
SP - 103
EP - 112
JO - Analytica Chimica Acta
JF - Analytica Chimica Acta
SN - 0003-2670
ER -