学術雑誌論文

学術雑誌論文

text

Langmuir. 2023, 39(43), p. 15189-15199

Passive Translocation of Phospholipids in Asymmetric Model Membranes: Solid-State 1H NMR Characterization of Flip-Flop Kinetics Using Deuterated Sphingomyelin and Phosphatidylcholine

American Chemical Society

英語

text

2023-10-31

https://doi.org/10.1021/acs.langmuir.3c01650

Watanabe H., Hanashima S., Yano Y., et al. Passive Translocation of Phospholipids in Asymmetric Model Membranes: Solid-State 1H NMR Characterization of Flip-Flop Kinetics Using Deuterated Sphingomyelin and Phosphatidylcholine. Langmuir 39, 15189 (2023); https://doi.org/10.1021/acs.langmuir.3c01650.

Although lateral and inter-leaflet lipid-lipid interactions in cell membranes play roles in maintaining asymmetric lipid bilayers, the molecular basis of these interactions is largely unknown. Here, we established a method to determine the distribution ratio of phospholipids between the outer and inner leaflets of asymmetric large unilamellar vesicles (aLUVs). The trimethylammonium group, (CH3)3N+, in the choline headgroup of N-palmitoyl-sphingomyelin (PSM) and 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) gave rise to a relatively sharp signal in magic-angle spinning solid-state 1H NMR (MAS-ss-1H NMR). PSM and DOPC have the same headgroup structure, but one phospholipid was selectively observed by deuterating the trimethylammonium group of the other phospholipid. The addition of Pr3+ to the medium surrounding aLUVs selectively shifted the chemical shift of the (CH3)3N+ group in the outer leaflet from that in the inner leaflet, which allowed estimation of the inter-leaflet distribution ratio of the unlabeled lipid in aLUVs. Using this method, we evaluated the translocation of PSM and DOPC between the outer and inner leaflets of the cholesterol-containing aLUVs, with PSM and DOPC mostly distributed in the outer and inner leaflets, respectively, immediately after aLUV preparation; their flip and flop rates were approximately 2.7 and 6.4 × 10-6 s-1, respectively. During the passive symmetrization of aLUVs, the lipid translocation rate was decreased due to changes in the membrane order, probably through the formation of the registered liquid-ordered domains. Comparison of the result with that of symmetric LUVs revealed that lipid asymmetry may not significantly affect the lipid translocation rates, while the lateral lipid-lipid interaction may be a dominant factor in lipid translocation under these conditions. These findings highlight the importance of considering the effects of lateral lipid interactions within the same leaflet on lipid flip-flop rates when evaluating the asymmetry of phospholipids in the cell membrane.

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.langmuir.3c01650.

95488

Passive Translocation of Phospholipids in Asymmetric Model Membranes: Solid-State 1H NMR Characterization of Flip-Flop Kinetics Using Deuterated Sphingomyelin and Phosphatidylcholine

American Chemical Society

英語

2023-10-31

Langmuir

39

43

15189

15199

https://doi.org/10.1021/acs.langmuir.3c01650

https://hdl.handle.net/11094/95488