Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2
Photosynthetic purple bacteria convert solar energy to chemical energy with near unity quantum efficiency. The light-harvesting process begins with absorption of solar energy by an antenna protein called Light-Harvesting Complex 2 (LH2). Energy is subsequently transferred within LH2 and then through...
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| Format: | Article |
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Royal Society of Chemistry (RSC)
2018
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| Online Access: | http://hdl.handle.net/1721.1/118591 https://orcid.org/0000-0002-3901-4392 https://orcid.org/0000-0001-7003-6525 https://orcid.org/0000-0001-7616-7809 https://orcid.org/0000-0001-7746-2981 |
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| author | Lu, Yue Blankenship, Robert E. Ogren, John I Tong, Ashley L. Gordon, Samuel C. Chenu, Aurelia Cao, Jianshu Schlau-Cohen, Gabriela S |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Lu, Yue Blankenship, Robert E. Ogren, John I Tong, Ashley L. Gordon, Samuel C. Chenu, Aurelia Cao, Jianshu Schlau-Cohen, Gabriela S |
| author_sort | Lu, Yue |
| collection | MIT |
| description | Photosynthetic purple bacteria convert solar energy to chemical energy with near unity quantum efficiency. The light-harvesting process begins with absorption of solar energy by an antenna protein called Light-Harvesting Complex 2 (LH2). Energy is subsequently transferred within LH2 and then through a network of additional light-harvesting proteins to a central location, termed the reaction center, where charge separation occurs. The energy transfer dynamics of LH2 are highly sensitive to intermolecular distances and relative organizations. As a result, minor structural perturbations can cause significant changes in these dynamics. Previous experiments have primarily been performed in two ways. One uses non-native samples where LH2 is solubilized in detergent, which can alter protein structure. The other uses complex membranes that contain multiple proteins within a large lipid area, which make it difficult to identify and distinguish perturbations caused by protein-protein interactions and lipid-protein interactions. Here, we introduce the use of the biochemical platform of model membrane discs to study the energy transfer dynamics of photosynthetic light-harvesting complexes in a near-native environment. We incorporate a single LH2 from Rhodobacter sphaeroides into membrane discs that provide a spectroscopically amenable sample in an environment more physiological than detergent but less complex than traditional membranes. This provides a simplified system to understand an individual protein and how the lipid-protein interaction affects energy transfer dynamics. We compare the energy transfer rates of detergent-solubilized LH2 with those of LH2 in membrane discs using transient absorption spectroscopy and transient absorption anisotropy. For one key energy transfer step in LH2, we observe a 30% enhancement of the rate for LH2 in membrane discs compared to that in detergent. Based on experimental results and theoretical modeling, we attribute this difference to tilting of the peripheral bacteriochlorophyll in the B800 band. These results highlight the importance of well-defined systems with near-native membrane conditions for physiologically-relevant measurements. |
| first_indexed | 2024-09-23T11:04:36Z |
| format | Article |
| id | mit-1721.1/118591 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T11:04:36Z |
| publishDate | 2018 |
| publisher | Royal Society of Chemistry (RSC) |
| record_format | dspace |
| spelling | mit-1721.1/1185912022-09-27T16:59:43Z Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2 Lu, Yue Blankenship, Robert E. Ogren, John I Tong, Ashley L. Gordon, Samuel C. Chenu, Aurelia Cao, Jianshu Schlau-Cohen, Gabriela S Massachusetts Institute of Technology. Department of Chemistry Ogren, John I Tong, Ashley L. Gordon, Samuel C. Chenu, Aurelia Cao, Jianshu Schlau-Cohen, Gabriela S Photosynthetic purple bacteria convert solar energy to chemical energy with near unity quantum efficiency. The light-harvesting process begins with absorption of solar energy by an antenna protein called Light-Harvesting Complex 2 (LH2). Energy is subsequently transferred within LH2 and then through a network of additional light-harvesting proteins to a central location, termed the reaction center, where charge separation occurs. The energy transfer dynamics of LH2 are highly sensitive to intermolecular distances and relative organizations. As a result, minor structural perturbations can cause significant changes in these dynamics. Previous experiments have primarily been performed in two ways. One uses non-native samples where LH2 is solubilized in detergent, which can alter protein structure. The other uses complex membranes that contain multiple proteins within a large lipid area, which make it difficult to identify and distinguish perturbations caused by protein-protein interactions and lipid-protein interactions. Here, we introduce the use of the biochemical platform of model membrane discs to study the energy transfer dynamics of photosynthetic light-harvesting complexes in a near-native environment. We incorporate a single LH2 from Rhodobacter sphaeroides into membrane discs that provide a spectroscopically amenable sample in an environment more physiological than detergent but less complex than traditional membranes. This provides a simplified system to understand an individual protein and how the lipid-protein interaction affects energy transfer dynamics. We compare the energy transfer rates of detergent-solubilized LH2 with those of LH2 in membrane discs using transient absorption spectroscopy and transient absorption anisotropy. For one key energy transfer step in LH2, we observe a 30% enhancement of the rate for LH2 in membrane discs compared to that in detergent. Based on experimental results and theoretical modeling, we attribute this difference to tilting of the peripheral bacteriochlorophyll in the B800 band. These results highlight the importance of well-defined systems with near-native membrane conditions for physiologically-relevant measurements. United States. Department of Energy. Office of Basic Energy Sciences (Award DE-SC0018097) 2018-10-16T19:15:32Z 2018-10-16T19:15:32Z 2018-02 2017-11 2018-09-28T11:50:09Z Article http://purl.org/eprint/type/JournalArticle 2041-6520 2041-6539 http://hdl.handle.net/1721.1/118591 Ogren, John I. et al. “Impact of the Lipid Bilayer on Energy Transfer Kinetics in the Photosynthetic Protein LH2.” Chemical Science 9, 12 (2018): 3095–3104 © 2018 The Royal Society of Chemistry https://orcid.org/0000-0002-3901-4392 https://orcid.org/0000-0001-7003-6525 https://orcid.org/0000-0001-7616-7809 https://orcid.org/0000-0001-7746-2981 http://dx.doi.org/10.1039/C7SC04814A Chemical Science Creative Commons Attribution-NonCommercial 4.0 International http://creativecommons.org/licenses/by-nc/4.0/ application/pdf Royal Society of Chemistry (RSC) Royal Society of Chemistry |
| spellingShingle | Lu, Yue Blankenship, Robert E. Ogren, John I Tong, Ashley L. Gordon, Samuel C. Chenu, Aurelia Cao, Jianshu Schlau-Cohen, Gabriela S Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2 |
| title | Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2 |
| title_full | Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2 |
| title_fullStr | Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2 |
| title_full_unstemmed | Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2 |
| title_short | Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2 |
| title_sort | impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein lh2 |
| url | http://hdl.handle.net/1721.1/118591 https://orcid.org/0000-0002-3901-4392 https://orcid.org/0000-0001-7003-6525 https://orcid.org/0000-0001-7616-7809 https://orcid.org/0000-0001-7746-2981 |
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