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Iron-starvation-induced Protein A
Iron-starvation-induced protein A, also known as isiA, is a photosynthesis-related chlorophyll-containing protein found in cyanobacteria. It belongs to the chlorophyll-a/b-binding family of proteins, and has been shown to have a photoprotective, photoprotection role in preventing oxidative damage via energy dissipation. It was originally identified under Fe starvation, and thus received the name iron-starvation-induced protein A. However, the protein has more recently been found to respond to a variety of stress conditions such as high irradiance. It can aggregate with carotenoids and form rings around the PSI reaction center complexes to aid in photoprotective energy dissipation. Antenna function IsiA functions as an antenna for photosystem I (PSI) under iron-limiting conditions, when phycobilisomes disappear. In the (PSI)3(Isi3)18 complex most of the harvested energy is probably used by PSI; in other PSI-containing supercomplexes a large part of the energy will probably not be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanobacteria
Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteria's informal common name, blue-green algae. Cyanobacteria are probably the most numerous taxon to have ever existed on Earth and the first organisms known to have produced oxygen, having appeared in the middle Archean eon and apparently originated in a freshwater or terrestrial environment. Their photopigments can absorb the red- and blue-spectrum frequencies of sunlight (thus reflecting a greenish color) to split water molecules into hydrogen ions and oxygen. The hydrogen ions are used to react with carbon dioxide to produce complex organic compounds such as carbohydrates (a process known as carbon fixation), and the oxygen is released as a byproduct. By continuously producing and releasing oxygen over billions of years, cyanobacte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoprotective
Photoprotection is the biochemical process that helps organisms cope with molecular damage caused by sunlight. Plants and other oxygenic phototrophs have developed a suite of photoprotective mechanisms to prevent photoinhibition and oxidative stress caused by excess or fluctuating light conditions. Humans and other animals have also developed photoprotective mechanisms to avoid UV photodamage to the skin, prevent direct DNA damage, DNA damage, and minimize the indirect DNA damage, downstream effects of oxidative stress. In photosynthetic organisms In organisms that perform photosynthesis, oxygenic photosynthesis, excess light may lead to photoinhibition Photoinhibition is light-induced reduction in the photosynthetic capacity of a plant, alga, or cyanobacterium. Photosystem II (PSII) is more sensitive to light than the rest of the photosynthetic machinery, and most researchers define the term as ..., or photoinactivation of the photosynthetic reaction center, reaction centers, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosystem II Light-harvesting Protein
Photosystem II light-harvesting proteins are the intrinsic transmembrane proteins CP43 (PsbC) and CP47 (PsbB) occurring in the reaction centre of photosystem II (PSII). These polypeptides bind to chlorophyll ''a'' and β-Carotene and pass the excitation energy on to the reaction centre. This family also includes the iron-stress induced chlorophyll-binding protein CP43', encoded by the IsiA gene, which evolved in cyanobacteria from a PSII protein to cope with light limitations and stress conditions. Under iron-deficient growth conditions, CP43' associates with photosystem I (PSI) to form a complex that consists of a ring of 18 or more CP43' molecules around a PSI trimer, which significantly increases the light-harvesting system of PSI. The ''IsiA'' protein can also provide photoprotection for PSII. Plants, algae and some bacteria use two photosystems, PSI with P700 and PSII with P680. Using light energy, PSII acts first to channel an electron through a series of acceptors that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
