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| - | <StructureSection load=' | + | <StructureSection load='1FBB' size='500' side='right' caption='3D Structure of Bacteriorhodopsin' scene=''> |
| - | + | == '''Bacteriorhodopsin''' == | |
| - | </ | + | ==Structure== |
| + | Bacteriorhodopsin is an integral membrane protein that functions as a proton pump. It has a primary structure that includes 248 amino acids with a molecular weight of 26,800.58 Da.<ref>Khorana, H. G.; Gerber, G. E.; Herlihy, W. C.; Gray, C. H.; Anderegg, R. J.; Nihei, K.; Biemann, K. Amino acid sequence of bacteriorhodopsin. ''Proc. Natl. Acad. Sci.'' USA '''1997''', 76 (10), 5046-5050.</ref> The <scene name='91/919042/Secondary_structure/2'>secondary structure</scene> is seen in the seven alpha helices (deep pink) and two beta strands (yellow) that are antiparallel. Located in the center is the ligand, <scene name='91/919042/Ret_300/2'>RET 300</scene> which is bonded to <scene name='91/919042/Lys_216/1'>Lys216</scene>. The alpha helices contain specific charged <scene name='91/919042/Polar/2'>polar</scene> (pink) sides that help carry the proton through the middle of the protein's hydrophilic membrane <ref>Luecke, H.; Schobert, B.; Ricther, H. T.; Cartailler, J. P.; Lanyi, J. Structure of Bacteriorhodopsin at 1.55 Å Resolution. ''JMBI''. '''1999''', 291 (4), 899-911.</ref>.<scene name='91/919042/3d_structure/2'>The tertiary structure </scene> includes one domain and an alpha bundle motif. <ref>Edman, K.; Nollert, P.; Royant, A.; Belrhali, H.; Pebay-Peyroula, E.; Hajdu, J.; Neutze, R.; Landau, E. M. High resolution x-ray structure of an early intermediate in the bacteriorhodopsin photocycle. ''RSCB PDB''. '''1999''', 401 (6755), 822-826.</ref> The quaternary structure has C3 symmetry and is a homotrimer with three subunits.<ref>Ovchinnikov, Y. A.; Abdulaev, N. G.; Feigina, M. Y.; Kiselev, A. V.; Lobanov, N. A. The structural basis of the functioning of bacteriorhodopsin: an overview. ''ICHB''. '''1979''', 100 (2), 219-224.</ref> | ||
| - | =='''Bacteriorhodopsin'''== | ||
| - | ==Structure== | ||
| - | Bacteriorhodopsin is an integral membrane protein that functions as a proton pump. It has a primary structure that includes 248 amino acids. The secondary structure is seen in the seven alpha helices and two | ||
| - | <Structure load='1MGY' size='350' frame='true' align='right' caption='One subunit of Bacteriorhodopsin' scene='Insert optional scene name here' /> | ||
== Function == | == Function == | ||
| - | Bacteriorhodopsin functions as a proton pump that transports H+ across the gradient and is driven by green light. The protons are used to create ATP which is a vital part of the haloarchaea's survival. Once bacteriorhodopsin absorbs a photon, catalysis is triggered, causing a conformational shift from trans to cis, a release of a proton, and a transfer of a proton. The catalytic cycle includes 6 steps of isomerization, accessibility change, and ion transport ( | + | Bacteriorhodopsin functions as a proton pump that transports H+ across the gradient and is driven by green light(500nm-650nm).<ref>Lanyi, J. K.; Varo, G. The photocycles of bacteriorhodopsin. ''Isr. J. Chem''. '''1995''', 35 (3-4), 365-385.</ref> Hydrophobic lipid tails are able to interact with proteins' rigid surfaces while keeping a hydrophilic center that allows the movement of protons.<ref>Belrhalo, H.; Nollert, P.; Royant, A.; Menzel, C.; Rosenbusch, J.; Landau, E.; Ebay-Peyroula, E. Protein, Lipid and Water Organization in Bacteriorhodopsin Crystals: A Molecular View of the Purple Membrane at 1.9 Å Resolution. ''Struc.'' '''1999''', 7 (8), 909-917.</ref> The protons are used to create ATP which is a vital part of the haloarchaea's survival. Once bacteriorhodopsin absorbs a photon, catalysis is triggered, causing a conformational shift from trans to cis, a release of a proton, and a transfer of a proton. The catalytic cycle includes 6 steps of isomerization, accessibility change, and ion transport. <ref>Ovichinnikov, Y. A.; Rhodopsin and bacteriorhodopsin structure--function relationships. ''IBCH.'' USSR '''1982''', 148 (2), 179-191.</ref> <ref>Noort, J. Unraveling bacteriorhodopsin. ''Biophys. J.'' '''2005''', 88 (2), 763-764.</ref> The first step of the catalytic cycle is the photoisomerization by retinol to cause all trans to configure into 13-cis. The change allows the Schiff Base to transfer a proton to asp 85. Aspartic acid 96 then reprotonates the Schiff Base via the cytoplasmic channel, causing the retinol reverses the conformational change, returning to all trans<ref>Tittor, J.; Paula, S.; Subramaniam, J.; Herberle, R.; Henderson, Oesterhelt, D. Proton Translocation by Bacteriorhodopsin in Absence of Substantial Comformational Changes. ''J. Mol. Biol.'' '''2002''' 319, 555-565. </ref>. Bacteriorhodopsin is a type three membrane protein. The side chains of the amino acids are hydrophobic, causing a highly hydrophobic membrane protein pump. Hydrophobia is very common in membrane proteins. |
== Relevance == | == Relevance == | ||
| - | Without bacteriorhodopsin, the light would not be converted into the energy that drives the proton pump, making it much harder for bacteria cells to produce the ATP needed to function normally. Bacteriorhodopsin is also essential in helping the bacteria cells create a chemical gradient for sodium, and assists in creating the energy needed for the cell to rotate its flagella. The energy it helps create helps normal cell function, such as the transport of amino acids, occur. A lack of bacteriorhodopsin would be detrimental to these bacterial cells | + | Without bacteriorhodopsin, the light would not be converted into the energy that drives the proton pump, making it much harder for bacteria cells to produce the ATP needed to function normally.<ref>Stoeckenius, W.; Bogomolni, R. A. Bacteriorhodopsin and related pigments of halobacteria. ''Ann. Rev. Biochem''. '''1982''', 52, 587-616.</ref> Bacteriorhodopsin is also essential in helping the bacteria cells create a chemical gradient for sodium, and assists in creating the energy needed for the cell to rotate its flagella. The energy it helps create helps normal cell function, such as the transport of amino acids, occur. A lack of bacteriorhodopsin would be detrimental to these bacterial cells <ref>Kouyama, T.; Kinosita, K.; Ikegami, A. Structure and Function of Bacteriorhodopsin. ''Adv. Biophys.'' '''1988''', 24, 123–175.</ref>. |
== Enzyme Mechanism == | == Enzyme Mechanism == | ||
| - | Aspartic Acids 96 and 85 play a very important role in the function of bacteriorhodopsin. When substituted into glutamine, less than 10% of normal function will occur. If they are substituted or a mutation occurs, normal processes of bacteriorhodopsin will not occur due to the slow photocycle | + | Aspartic Acids 96 and 85 play a very important role in the function of bacteriorhodopsin.<ref> Haupts, U.; Tittor, J.; Oesterhelt, D. Closing in on bacteriorhodopsin: progress in understanding the molecule. ''Annu. Rev. Biophys. Biomol. Struct.'' '''1999''', 28, 367-399.</ref> When substituted into glutamine, less than 10% of normal function will occur.<ref>Mogi, T.; Stern, L. J.; Marti, T.; Chao, B. H.; Khorana, H. G. Aspartic Acid Substitutions Affect Proton Translocation by Bacteriorhodopsin. ''Proc. Natl. Acad. Sci.'' USA. '''1988''', 85 (12), 4148–4152.</ref> If they are substituted or a mutation occurs, normal processes of bacteriorhodopsin will not occur due to the slow photocycle. <scene name='91/919042/Asp85/1'>Aspartic acid 85</scene> is responsible for proton release for the bacteriorhodopsin. <scene name='91/919042/Asp96/1'>Aspartic acid 96</scene> is responsible for the deprotonation and protonation of the Schiff Base.<ref>Butt, H. J.; Fendler, K.; Bamberg, E.; Tittor, J.; Oesterhelt, D. Aspartic acids 96 and 85 play a central role in the function of bacteriorhodopsin as a proton pump. ''EMBO''. '''1989''', 8 (6), 1657-1663</ref> The <scene name='91/919042/Schiff_base/1'>Schiff Base</scene> is a catalytic ligand that is equidistant between Aspartic acids 85 and 212 and it contains three water molecules. It is a planar pentagonal cluster and protonated, counteracting the negative charge of the Aspartic acids, and has one oxygen from each amino acid. Once light is absorbed, the photoisomerization step takes place, causing a conformational change from all-trans to 13-cis. The Schiff base then transfers a proton to Asp85, causing the downstream effect of proton transfer reactions. <ref>Shibata, M.; Tanimoto, T.; Kandori, H. Water Molecules in the Schiff Base Molecules. ''J. Am. Chem. Soc.'' '''2003''' 125 (44) 13312–13313 |
| + | </ref> | ||
== Interesting Findings == | == Interesting Findings == | ||
| - | Halophilic archaea live in hypersaline environments such as salt lakes and are exposed to extremely strong sunlight. This increases the salinity so the haloarchaea depend on the proton gradient system through its photo-reactive proteins. Due to bacteriorhodopsin having low availability at a high price, studies have produced a BR recombinant protein called highly expressible bacteriorhodopsin (HEBR). HEBR may decrease the likelihood of cell | + | Halophilic archaea live in hypersaline environments such as salt lakes and are exposed to extremely strong sunlight. This increases the salinity so the haloarchaea depend on the proton gradient system through its photo-reactive proteins. Due to bacteriorhodopsin having low availability at a high price, studies have produced a BR recombinant protein called highly expressible bacteriorhodopsin (HEBR). This particular version of bacteriorhodopsin absorbs light at 532nm also known as green light. In studies of lung cancer, voltage-gated control seems to be the spot check of cell proliferation. With HEBR to control the depolarization and hyperpolarization, HEBR may decrease the likelihood of cell multiplication and migration of lung cancer cells.<ref>Wong, C. W.; Ko, L. N.; Huang, H. J.; Yang, C. S.; Hsu, S. H. Engineered bacteriorhodopsin may induce lung cancer cell cycle arrest and suppress their proliferation and migration. ''MDPI''. '''2021''', 26 (23).</ref> |
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== References == | == References == | ||
<references/> | <references/> | ||
| - | Butt, H. J.; Fendler, K.; Bamberg, E.; Tittor, J.; Oesterhelt, D. | ||
| - | Aspartic acids 96 and 85 play a central role in the function of bacteriorhodopsin as a proton pump. ''EMBO''. '''1989''', 8 (6), 1657-1663. | ||
| - | |||
| - | Edman, K.; Nollert, P.; Royant, A.; Belrhali, H.; Pebay-Peyroula, E.; Hajdu, J.; Neutze, R.; Landau, E. M. High resolution x-ray structure of an early intermediate in the bacteriorhodopsin photocycle. ''RSCB'' PDB. '''1999''', 401 (6755), 822-826. | ||
| - | |||
| - | Haupts, U.; Tittor, J.; Oesterhelt, D. Closing in on bacteriorhodopsin: progress in understanding the molecule. ''Annu. Rev. Biophys. Biomol. Struct.'' '''1999''', 28, 367-399. | ||
| - | |||
| - | Khorana, H. G.; Gerber, G. E.; Herlihy, W. C.; Gray, C. H.; Anderegg, R. J.; Nihei, K.; Biemann, K. Amino acid sequence of bacteriorhodopsin. ''Proc. Natl. Acad. Sci.'' USA '''1997''', 76 (10), 5046-5050. | ||
| - | |||
| - | Lanyi, J. K.; Varo, G. The photocycles of bacteriorhodopsin. ''Isr. J. Chem.'' '''1995''', 35 (3-4), 365-385. | ||
| - | |||
| - | Noort, J. Unraveling bacteriorhodopsin. ''Biophys. J.'' '''2005''', 88 (2), 763-764. | ||
| - | |||
| - | Ovchinnikov, Y. A.; Abdulaev, N. G.; Feigina, M. Y.; Kiselev, A. V.; Lobanov, N. A. The structural basis of the functioning of bacteriorhodopsin: an overview. ''ICHB''. '''1979''', 100 (2), 219-224. | ||
| - | |||
| - | Ovichinnikov, Y. A.; Rhodopsin and bacteriorhodopsin structure--function relationships. ''IBCH''. USSR '''1982''', 148 (2), 179-191. | ||
| - | |||
| - | Stoeckenius, W.; Bogomolni, R. A. Bacteriorhodopsin and related pigments of halobacteria. ''Ann. Rev. Biochem.'' '''1982''', 52, 587-616. | ||
| - | |||
| - | Wong, C. W.; Ko, L. N.; Huang, H. J.; Yang, C. S.; Hsu, S. H. Engineered bacteriorhodopsin may induce lung cancer cell cycle arrest and suppress their proliferation and migration. ''MDPI''. '''2021''', 26 (23). | ||
| - | |||
| - | Kouyama, T.; Kinosita, K.; Ikegami, A. Structure and Function of Bacteriorhodopsin. ''Adv. Biophys.'' '''1988''', 24, 123–175. | ||
| - | |||
| - | Mogi, T.; Stern, L. J.; Marti, T.; Chao, B. H.; Khorana, H. G. Aspartic Acid Substitutions Affect Proton Translocation by Bacteriorhodopsin. ''Proc. Natl. Acad. Sci.'' USA. '''1988''', 85 (12), 4148–4152. | ||
Current revision
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References
- ↑ Khorana, H. G.; Gerber, G. E.; Herlihy, W. C.; Gray, C. H.; Anderegg, R. J.; Nihei, K.; Biemann, K. Amino acid sequence of bacteriorhodopsin. Proc. Natl. Acad. Sci. USA 1997, 76 (10), 5046-5050.
- ↑ Luecke, H.; Schobert, B.; Ricther, H. T.; Cartailler, J. P.; Lanyi, J. Structure of Bacteriorhodopsin at 1.55 Å Resolution. JMBI. 1999, 291 (4), 899-911.
- ↑ Edman, K.; Nollert, P.; Royant, A.; Belrhali, H.; Pebay-Peyroula, E.; Hajdu, J.; Neutze, R.; Landau, E. M. High resolution x-ray structure of an early intermediate in the bacteriorhodopsin photocycle. RSCB PDB. 1999, 401 (6755), 822-826.
- ↑ Ovchinnikov, Y. A.; Abdulaev, N. G.; Feigina, M. Y.; Kiselev, A. V.; Lobanov, N. A. The structural basis of the functioning of bacteriorhodopsin: an overview. ICHB. 1979, 100 (2), 219-224.
- ↑ Lanyi, J. K.; Varo, G. The photocycles of bacteriorhodopsin. Isr. J. Chem. 1995, 35 (3-4), 365-385.
- ↑ Belrhalo, H.; Nollert, P.; Royant, A.; Menzel, C.; Rosenbusch, J.; Landau, E.; Ebay-Peyroula, E. Protein, Lipid and Water Organization in Bacteriorhodopsin Crystals: A Molecular View of the Purple Membrane at 1.9 Å Resolution. Struc. 1999, 7 (8), 909-917.
- ↑ Ovichinnikov, Y. A.; Rhodopsin and bacteriorhodopsin structure--function relationships. IBCH. USSR 1982, 148 (2), 179-191.
- ↑ Noort, J. Unraveling bacteriorhodopsin. Biophys. J. 2005, 88 (2), 763-764.
- ↑ Tittor, J.; Paula, S.; Subramaniam, J.; Herberle, R.; Henderson, Oesterhelt, D. Proton Translocation by Bacteriorhodopsin in Absence of Substantial Comformational Changes. J. Mol. Biol. 2002 319, 555-565.
- ↑ Stoeckenius, W.; Bogomolni, R. A. Bacteriorhodopsin and related pigments of halobacteria. Ann. Rev. Biochem. 1982, 52, 587-616.
- ↑ Kouyama, T.; Kinosita, K.; Ikegami, A. Structure and Function of Bacteriorhodopsin. Adv. Biophys. 1988, 24, 123–175.
- ↑ Haupts, U.; Tittor, J.; Oesterhelt, D. Closing in on bacteriorhodopsin: progress in understanding the molecule. Annu. Rev. Biophys. Biomol. Struct. 1999, 28, 367-399.
- ↑ Mogi, T.; Stern, L. J.; Marti, T.; Chao, B. H.; Khorana, H. G. Aspartic Acid Substitutions Affect Proton Translocation by Bacteriorhodopsin. Proc. Natl. Acad. Sci. USA. 1988, 85 (12), 4148–4152.
- ↑ Butt, H. J.; Fendler, K.; Bamberg, E.; Tittor, J.; Oesterhelt, D. Aspartic acids 96 and 85 play a central role in the function of bacteriorhodopsin as a proton pump. EMBO. 1989, 8 (6), 1657-1663
- ↑ Shibata, M.; Tanimoto, T.; Kandori, H. Water Molecules in the Schiff Base Molecules. J. Am. Chem. Soc. 2003 125 (44) 13312–13313
- ↑ Wong, C. W.; Ko, L. N.; Huang, H. J.; Yang, C. S.; Hsu, S. H. Engineered bacteriorhodopsin may induce lung cancer cell cycle arrest and suppress their proliferation and migration. MDPI. 2021, 26 (23).
