論文

査読有り 国際誌
2019年6月20日

A concise method for quantitative analysis of interactions between lipids and membrane proteins.

Analytica chimica acta
  • Masataka Inada
  • ,
  • Masanao Kinoshita
  • ,
  • Ayumi Sumino
  • ,
  • Shigetoshi Oiki
  • ,
  • Nobuaki Matsumori

1059
開始ページ
103
終了ページ
112
記述言語
英語
掲載種別
DOI
10.1016/j.aca.2019.01.042

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 C6-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 C6-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 C6-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 C6-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.

リンク情報
DOI
https://doi.org/10.1016/j.aca.2019.01.042
PubMed
https://www.ncbi.nlm.nih.gov/pubmed/30876624

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