Sandbox Reserved 819
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Archaerhodopsin-2 (aR2) is a light-driven proton pump. It is a retinal protein–carotenoid complex found in the claret membrane of Halorubrum sp. aus-2. In these membranes, three Archaerhodopsin-2 form a trimeric structure, capturing light energy and using it to move protons across the membrane out of the cell.The resulting proton gradient is subsequently converted into chemical energy. The trimerization increases the thermal stability of the protein aR2 in the claret membrane of Halorubrum sp. aus-2 and enlarges the pH range where the protein can keep its neutral purple conformation.The trimerization increases the efficiency of the proton pumping power, which is defined by the largest pH gradient that the proton pump can generate across the membrane. So, the trimeric structure is more efficient than the monomeric structure. | Archaerhodopsin-2 (aR2) is a light-driven proton pump. It is a retinal protein–carotenoid complex found in the claret membrane of Halorubrum sp. aus-2. In these membranes, three Archaerhodopsin-2 form a trimeric structure, capturing light energy and using it to move protons across the membrane out of the cell.The resulting proton gradient is subsequently converted into chemical energy. The trimerization increases the thermal stability of the protein aR2 in the claret membrane of Halorubrum sp. aus-2 and enlarges the pH range where the protein can keep its neutral purple conformation.The trimerization increases the efficiency of the proton pumping power, which is defined by the largest pH gradient that the proton pump can generate across the membrane. So, the trimeric structure is more efficient than the monomeric structure. | ||
| - | The trimeric structure functions as a light-driven proton pump thanks to a retinal molecule, called RET, which changes its conformation when absorbing a photon, resulting in a conformational change of the surrounding protein and the proton pumping action. Others ligands are linked with each subunit of the trimeric structure like the bacterioruberin or the 2,3-di-phytanyl-glycerol. Several saccharides are also linked to the trimeric structure. The bacterioruberin is a 50 carbon carotenoid pigment which give a red color to the membrane . The primary role of bacterioruberin in the cell is to protect against DNA damage incurred by UV light. This protection is not, however, due to the ability of bacterioruberin to absorb UV light. Bacterioruberin protects the DNA by acting as an antioxidant, rather than directly blocking UV light. It is able to protect the cell from reactive oxygen species produced from exposure to UV by acting as a target. The bacterioruberin radical produced is less reactive than the initial radical, and will likely react with another radical, resulting in termination of the radical chain reaction. | + | The trimeric structure functions as a light-driven proton pump thanks to a retinal molecule, called RET, which changes its conformation when absorbing a photon, resulting in a conformational change of the surrounding protein and the proton pumping action. Others ligands are linked with each subunit of the trimeric structure like the bacterioruberin or the 2,3-di-phytanyl-glycerol. Several saccharides are also linked to the trimeric structure. The bacterioruberin is a 50 carbon carotenoid pigment which give a red color to the membrane . The primary role of bacterioruberin in the cell is to protect against DNA damage incurred by UV light. This protection is not, however, due to the ability of bacterioruberin to absorb UV light. Bacterioruberin protects the DNA by acting as an antioxidant, rather than directly blocking UV light. It is able to protect the cell from reactive oxygen species produced from exposure to UV by acting as a target. The bacterioruberin radical produced is less reactive than the initial radical, and will likely react with another radical, resulting in termination of the radical chain reaction. Furthermore, the bacterioruberin is essential because it plays a structural role for the trimerization of aR2. |
Revision as of 16:23, 23 December 2013
| This Sandbox is Reserved from 06/12/2018, through 30/06/2019 for use in the course "Structural Biology" taught by Bruno Kieffer at the University of Strasbourg, ESBS. This reservation includes Sandbox Reserved 1480 through Sandbox Reserved 1543. |
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2Z55
The trimeric structure of Archaerhodopsin-2 and the bacterioruberin
Archaerhodopsin-2 (aR2) is a light-driven proton pump. It is a retinal protein–carotenoid complex found in the claret membrane of Halorubrum sp. aus-2. In these membranes, three Archaerhodopsin-2 form a trimeric structure, capturing light energy and using it to move protons across the membrane out of the cell.The resulting proton gradient is subsequently converted into chemical energy. The trimerization increases the thermal stability of the protein aR2 in the claret membrane of Halorubrum sp. aus-2 and enlarges the pH range where the protein can keep its neutral purple conformation.The trimerization increases the efficiency of the proton pumping power, which is defined by the largest pH gradient that the proton pump can generate across the membrane. So, the trimeric structure is more efficient than the monomeric structure.
The trimeric structure functions as a light-driven proton pump thanks to a retinal molecule, called RET, which changes its conformation when absorbing a photon, resulting in a conformational change of the surrounding protein and the proton pumping action. Others ligands are linked with each subunit of the trimeric structure like the bacterioruberin or the 2,3-di-phytanyl-glycerol. Several saccharides are also linked to the trimeric structure. The bacterioruberin is a 50 carbon carotenoid pigment which give a red color to the membrane . The primary role of bacterioruberin in the cell is to protect against DNA damage incurred by UV light. This protection is not, however, due to the ability of bacterioruberin to absorb UV light. Bacterioruberin protects the DNA by acting as an antioxidant, rather than directly blocking UV light. It is able to protect the cell from reactive oxygen species produced from exposure to UV by acting as a target. The bacterioruberin radical produced is less reactive than the initial radical, and will likely react with another radical, resulting in termination of the radical chain reaction. Furthermore, the bacterioruberin is essential because it plays a structural role for the trimerization of aR2.
