Biology:Phycobilisome
| Phycobilisome protein | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 The layout of protein subunits in a phycobilisome. | |||||||||
| Identifiers | |||||||||
| Symbol | Phycobilisome | ||||||||
| Pfam | PF00502 | ||||||||
| InterPro | IPR012128 | ||||||||
| SCOP2 | 1cpc / SCOPe / SUPFAM | ||||||||
| |||||||||
Phycobilisomes are light-harvesting antennae that transmit the energy of harvested photons to photosystem II and photosystem I in cyanobacteria and in the chloroplasts of red algae and glaucophytes.[1][2][3] They were lost during the evolution of the chloroplasts of green algae and plants.[3]
General structure
Phycobilisomes are protein complexes (up to 600 polypeptides) anchored to thylakoid membranes. They are made of stacks of chromophorylated proteins, the phycobiliproteins, and their associated linker polypeptides. Each phycobilisome consists of a core made of allophycocyanin, from which several outwardly oriented rods made of stacked disks of phycocyanin and (if present) phycoerythrin(s) or phycoerythrocyanin. The spectral property of phycobiliproteins are mainly dictated by their prosthetic groups, which are linear tetrapyrroles known as phycobilins including phycocyanobilin, phycoerythrobilin, phycourobilin and phycobiliviolin. The spectral properties of a given phycobilin are influenced by its protein environment.[4]
Function
Each phycobiliprotein has a specific absorption and fluorescence emission maximum in the visible range of light. Therefore, their presence and the particular arrangement within the phycobilisomes allow absorption and unidirectional transfer of light energy to chlorophyll a of the photosystem II. In this way, the cells take advantage of the available wavelengths of light (in the 500–650 nm range), which are inaccessible to chlorophyll, and utilize their energy for photosynthesis. This is particularly advantageous deeper in the water column, where light with longer wavelengths is less transmitted and therefore less available directly to chlorophyll.
The geometrical arrangement of a phycobilisome is very elegant in an antenna-like assembly. It results in 95% efficiency of energy transfer.[5]
Evolution and diversity
There are many variations to the general phycobilisome structure. Their shape can be hemidiscoidal (in cyanobacteria) or hemiellipsoidal (in red algae). Species lacking phycoerythrin have at least two disks of phycocyanin per rod, which is sufficient for maximum photosynthesis.[6]
Applications
Phycobilisomes can be used in prompt fluorescence,[7][8] flow cytometry,[9] Western blotting and protein microarrays. Some phycobilisomes have an absorption and emission profile similar to Cy5, allowing them to be used in many of the same applications. They can also be up to 200 times brighter and with a larger Stokes shift, providing a larger signal per binding event. This property allows the detection of low-level target molecules[9] or rare events.
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Excitation and emission spectra of a phycobilisome from a blue-green alga. -
Phycobilisome versus cyanine dye detection capabilities in Western blot application.
References
- ↑ "Core and rod structures of a thermophilic cyanobacterial light-harvesting phycobilisome". Nature Communications 13 (1): 3389. 2022. doi:10.1038/s41467-022-30962-9. PMID 35715389. Bibcode: 2022NatCo..13.3389K.
- ↑ "Structural organization of an intact phycobilisome and its association with photosystem II". Cell Research 25 (6): 726–737. 2015. doi:10.1038/cr.2015.59. PMID 25998682.
- ↑ 3.0 3.1 "Endosymbiotic Origin of Chloroplasts in Plant Cells' Evolution". Russian Journal of Plant Physiology 68 (1): 1–16. 2021. doi:10.1134/S1021443721010179. Bibcode: 2021RuJPP..68....1S.
- ↑ "The phycobilisomes: an early requisite for efficient photosynthesis in cyanobacteria". EXCLI Journal 14: 268–89. 2015. doi:10.17179/excli2014-723. PMID 26417362.
- ↑ "Light harvesting by phycobilisomes". Annual Review of Biophysics and Biophysical Chemistry 14: 47–77. June 1985. doi:10.1146/annurev.bb.14.060185.000403. PMID 3924069.
- ↑ "Phycobilisome-Deficient Strains of Synechocystis sp. PCC 6803 Have Reduced Size and Require Carbon-Limiting Conditions to Exhibit Enhanced Productivity". Plant Physiology 165 (2): 705–714. June 2014. doi:10.1104/pp.114.237206. PMID 24760817.
- ↑ "PBXL Fluorescent Dyes for Ultrasensitive Direct Detection". Journal of Fluorescence 9 (3): 197–208. 1999. doi:10.1023/A:1022503600141.
- ↑ "MicroPlate Detection comparison between SureLight®P-3L, other fluorophores and enzymatic detection". Technical Bulletin 3. Columbia Biosciences. 2010. https://store-7fikt.mybigcommerce.com/product_images/uploaded_images/Technical_Bulletin_3_ColBio_SureLightP3.pdf.
- ↑ 9.0 9.1 "Cyanobacterial stabilized phycobilisomes as fluorochromes for extracellular antigen detection by flow cytometry". Journal of Immunological Methods 254 (1–2): 13–30. August 2001. doi:10.1016/s0022-1759(01)00367-2. PMID 11406150. https://store-7fikt.mybigcommerce.com/product_images/uploaded_images/Telford_Cyanobacterial_stabilized_phycobilisomes-2001.pdf. Retrieved 2014-06-07.
Further reading
- "Structural insight into the mechanism of energy transfer in cyanobacterial phycobilisomes". Nature Communications 12: 5497. 2021. doi:10.1038/s41467-021-25813-y. PMID 34535665. Bibcode: 2021NatCo..12.5497Z.
External links
- Phycobilisomes at the US National Library of Medicine Medical Subject Headings (MeSH)
- Columbia Biosciences - Phycobilisome Resource
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