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additional information
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protein YGL8 has the dual functions in chlorophyll biosynthesis: one as a catalytic subunit of MgPME cyclase, the other as a core component of FLU-YGL8-LCAA-POR complex in chlorophyll biosynthesis, physical interaction between YGL8 and a rice chloroplast protein, low chlorophyll accumulation A (OsLCAA). YGL8 also interacts with the other two rice chloroplast proteins, viz. fluorescent (OsFLU1) and NADPH:protochlorophyllide oxidoreductase (OsPORB)
evolution
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phylogeny of the YL-1 protein family, overview
evolution
the enzyme belongs to the ferritin-like, diiron-carboxylate protein family
evolution
the process for the formation of the unique isocyclic fifth ring of chlorophyll involves the conversion of Mg-protoporphyrin IX monomethyl ester (MgPME) to 3,8-divinyl protochlorophyllide a (DV PChlide a), and it requires incorporation of an oxygen atom, sourced from either water or O2, indicating the existence of two mechanistically different MgPME cyclases. Most anoxygenic phototrophic bacteria utilise an O2-sensitive radical SAM enzyme containing [4Fe-4S] and cobalamin cofactors to catalyse the reaction, while oxygenic phototrophs including cyanobacteria, algae and plants, as well as some purple bacteria, adopt an O2-dependent cyclase for the reaction. Mg-protoporphyrin IX monomethyl ester (MgPME) cyclase catalyses the formation of the isocyclic ring, the hallmark of chlorins and bacteriochlorins, producing protochlorophyllide a and contributing significantly to the absorption properties of chlorophylls and bacteriochlorophylls. Three classes of O2-dependent cyclase have been identified, all with a catalytic subunit AcsF, a putative diiron protein, but they differ in the requirement for an auxiliary subunit, either Ycf54 for the enzyme found in oxygenic phototrophs, or BciE for the alphaproteobacterial enzyme
evolution
two distinct enzymes have been identified that catalyze the cyclase reaction, originally distinguished by the source of the incorporated oxygen. The enzyme that catalyzes the cyclase reaction in the absence of molecular oxygen (anaerobic) derives the oxygen from water and is encoded by bchE in facultative photosynthetic bacteria like Rhodobacter sphaeroides. The anaerobic enzyme functions as a hydratase, whereas the aerobic cyclase is an oxygenase. The aerobic cyclase belongs to the family of diiron carboxylate-bridged proteins characterized by the iron-binding motif E-Xn-E-X-X-H-Xn-E-Xn-E-X-X-H. The cyclase activity requires both additional soluble and membrane-bound fractions
malfunction
a Chl27-antisense Arabidopsis mutant accumulates the cyclase substrate magnesium-protoporphyrin IX monomethyl ester and does not produce protochlorophyllide a
malfunction
a Rubrivivax gelatinosus strain with disrupted acsF gene cannot synthesize bacteriochlorophyll under oxygenated conditions but accumulates the substrate magnesium-protoporphyrin IX monomethyl ester, in contrast, under low-oxygene conditions the phenotype is similar to the wild-type, an alternative pathway for the reaction exists vie the bchE genes
malfunction
crd1 strains fail to accumulate photosystem 1 (PS 1) and light-harvesting complex 1 (LHC 1) during hypoxia or copper deficiency, and have reduced amounts of LHC 2, Crd1 abundance is increased in copper or oxygen deficient cells
malfunction
Cth1 accumulates in copper-sufficient, oxygenated cells
malfunction
the Arabidopsis chl27-t knock-down mutant has a T-DNA insertion within the promoter region reducing mRNA levels dramatically, growth is slowed down and plants look pale due to chloroplast development defects (unstacking of thylakoid membranes), chlorophyll fluorescence analysis shows a low photosynthetic activity, numerous nuclear genes involved in pigment biosynthesis, photosynthesis (light-harvesting complex I and II, photo system I and II), for iron acquisition, carbon fixation, cold acclimation, and for electron carriers are repressed, stress and detoxifying related gene expression is affected most prominently, more than 600 genes are repressed, a similar number of genes are induced
malfunction
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transgenic tobacco with antisense NTZIP-RNA displays chlorosis and a lack of the ability to turn green under normal growth conditions
malfunction
xantha-l35 and viridis-k deficient mutants grown in the dark, fed with delta-aminolevulinic acid, accumulate the substrate magnesium-protoporphyrin IX monomethyl ester and produce reduced amounts of protochlorophyllide a, in vitro complementation assay with mutants the aerobic cyclase is composed of at least 3 gene products, 1 soluble and 2 membrane-bound proteins (xantha-l and viridian-k)
malfunction
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deficiency of the LCAA subunit affects Ala synthesis and the accumulation of proteins in tetrapyrrole biosynthesis
malfunction
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chlorophyll biosynthesis upstream genes are highly expressed in the yl-1 mutant, while downstream genes are compromised, indicating that enzyme MPEC plays a pivotal role in the chlorophyll biosynthesis. The yl-1 mutant shows a yellow leaf and panicle phenotype with reduced chlorophyll accumulation through the whole growth phases. Mutant yl-1 exhibits the temperature-independent yellow leaf phenotype, it presents abnormal chloroplast development and attenuated photosynthetic efficiency. The mutant yl-1 affects mRNA accumulation levels of Chl biosynthesis process
malfunction
decreased CHL27 transcript levels result in a substantial reduction of activity of MgPME cyclase and MgP monomethylester accumulation, in comparison to dexamethasone-treated wild-type seedlings
malfunction
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Hordeum vulgare mutants viridis-k, light green 3, light green 4 and zebra stripe 2 are not deficient in Ycf54. Both xanthan-l and viridis-k membranes are unable to support MPEC activity when combined with wild-type soluble fraction
malfunction
mutation of in enzyme MPEC causes the pale-green leaf mutant phenotype of mutant m167 with yellow-green leaves across the whole lifespan. Chlorophyll content decreases by 43-51% and the granal stacks of chloroplasts becomes thinner in m167. Chlorophyll fluorescence parameters, including Fv/Fm (the maximum quantum efficiency of PSII) and quantum yield of PSII (Y(II)), are lower in m167 than those in wild-type plants, and photosynthesis rate decreases by 40% in leaves of m167 mutant compared with wild-type plants, which leads to yield reduction in m167
malfunction
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Oryza sativa yellow-green leaf 8 (ygl8) mutant exhibits a chlorosis phenotype with abnormal chloroplast development in young leaves. During the development of leaves, the chlorotic plants turn green accompanied by restorations in chlorophyll content and chloroplast ultrastructure, expression levels of some nuclear genes associated with Chl biosynthesis are affected in both the ygl8 mutant and YGL8 RNA interference lines. YGL8 expression demonstrates no differences between the wild-type and ygl8 mutant plants, but the mutant shows increase of Proto IX and MgP/MgPME expression, accompanied with the decrease of protochlorophyllide. Phenotype, overview
malfunction
the Ycf54 protein forms a complex with the component of the oxidative cyclase, Sll1214 (CycI, gene slr1780). Partial inactivation of the ycf54 gene leads to chlorophyll deficiency in cyanobacteria and plants, and the complete deletion of the ycf54 gene in the cyanobacterium Synechocystis 6803 results accumulation of huge concentrations of the cyclase substrate MgPME together with 3-formyl MgPME, in the DELTAycf54 strain. The Ycf54 protein is important, but not essential, for activity of the oxidative cyclase. Phenotype, overview
malfunction
the yellow and spotted leaf 1 (ysl1) mutant in rice exhibits a yellow-green leaf phenotype throughout the whole developmental stage and a spotted leaf phenotype at seedling and tillering stages. The phenotype of ysl1 is caused by a single nucleotide substitution of Mg-protoporphyrin IX monomethyl ester cyclase YSL1 which is allelic to YGL8, OsCRD1, and YL-1
metabolism
enzyme is involved in the protochlorophyllide a synthesis
metabolism
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protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
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protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
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protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
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protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
protochlorophyllide a production (formation of the isocyclic ring) via several intermediates in the chlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
Roseibium alexandrii
magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
metabolism
in the chlorophyll biosynthesis pathway the formation of protochlorophyllide is catalyzed by Mg-protoporphyrin IX methyl ester (MgPME) cyclase. The requirement for de novo chlorophyll molecules differs completely for each chlorophyll-binding protein
metabolism
in the first unique step of the chlorophyll biosynthetic pathway, Mg2+ is inserted into protoporphyrin IX. Subsequently, a methyl group is transferred to the carboxyl group of the propionate on the C ring of Mg-protoporphyrin IX, generating Mg-protoporphyrin IX monomethyl ester (MPE), which is the substrate of the MPE cyclase. The cyclase catalyzes the formation of the isocyclic E ring by insertion of oxygen and attaching the methylated propionate to the methene bridge between pyrrole rings C and D, forming protochlorophyllide. Chlorophyll is obtained after additional reactions involving a light-dependent oxidation of protochlorophyllide to chlorophyllide, reduction of the vinyl group on the B ring, and, finally, addition of a polyisoprene tail
metabolism
Mg-protoporphyrin IX monomethyl ester cyclase (MPEC) plays an essential role in chlorophyll biosynthesis
metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
Roseibium alexandrii DFL-11
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
gammaproteobacteria NOR51-B
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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metabolism
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magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway
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physiological function
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an essential enzyme during chlorophyll (Chl) biosynthesis. The enzyme subunit protein YL-1 is required for plastid membrane stability. The formation of the isocyclic ring is an aerobic reaction catalyzed by MPEC in chloroplasts, which controls the conversion of magnesium-protoporphyrin IX 13-monomethyl ester to divinyl protochlorophyllide (DVpchlide). The function of YL-1 in MPEC complex is essential for normal chlorophyll biosynthesis
physiological function
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enzyme MPEC requires components found in both the membrane and soluble fractions of the chloroplast. It requires components associated with the plastid membrane and the plastid soluble fraction for activity. One of the components, XanL is found associated with the membrane and another protein, Ycf54 has been identified based upon its strong association of with XanL. The conserved chloroplast polypeptide Ycf54 is involved in the MPEC-enzyme catalyzed reaction
physiological function
MPEC is an essential enzyme in chlorophyll biosynthesis
physiological function
the enzyme catayzes the transformation of a side chain of magnesium protoporphyrin IX monomethyl ester cyclase (MgPMe)
physiological function
cyclic tetrapyrroles, are among the most abundant natural pigments on Earth. They are the major absorbers of the solar energy that drives photosynthesis, and billions of tonnes of chlorophyll are synthesised annually on land and in the oceans. The decisive biosynthetic step that determines the absorption properties of chlorophyll, and more visually its green color, is the formation of the unique isocyclic fifth ring. This process involves the conversion of Mg-protoporphyrin IX monomethyl ester (MgPME) to 3,8-divinyl protochlorophyllide a (DV PChlide a), and it requires incorporation of an oxygen atom, sourced from either water or O2, indicating the existence of two mechanistically different MgPME cyclases. Most anoxygenic phototrophic bacteria utilise an O2-sensitive radical SAM enzyme containing [4Fe-4S] and cobalamin cofactors to catalyse the reaction, while oxygenic phototrophs including cyanobacteria, algae and plants, as well as some purple bacteria, adopt an O2-dependent cyclase for the reaction. Mg-protoporphyrin IX monomethyl ester (MgPME) cyclase catalyses the formation of the isocyclic ring, the hallmark of chlorins and bacteriochlorins, producing protochlorophyllide a and contributing significantly to the absorption properties of chlorophylls and bacteriochlorophylls. The diiron cluster within AcsF is reduced by ferredoxin furnished by NADPH and ferredoxin:NADP+ reductase or by direct coupling to Photosystem I photochemistry, linking cyclase to the photosynthetic electron transport chain
physiological function
Mg-protoporphyrin IX monomethyl ester cyclase (MPEC) plays an essential role in chlorophyll biosynthesis
physiological function
the Xantha-l gene product (XanL) is a membrane-bound diiron monooxygenase, which requires additional soluble and membrane-bound components for its activity. The enzyme XanL is a Mg-protoporphyrin IX monomethyl ester cyclase involved in the formation of the isocyclic E-ring characteristic of chlorophylls. The MPE cyclase is a ferredoxin-dependent enzyme. Ferredoxin is part of the photosynthetic electron-transport chain, which suggests that the cyclase reaction might be connected to photosynthesis under light conditions