1.14.13.81	evolution	phylogeny of the YL-1 protein family, overview	746223	
1.14.13.81	evolution	the enzyme belongs to the ferritin-like, diiron-carboxylate protein family	744039	
1.14.13.81	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	765462	
1.14.13.81	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	765638	
1.14.13.81	malfunction	a Chl27-antisense Arabidopsis mutant accumulates the cyclase substrate magnesium-protoporphyrin IX monomethyl ester and does not produce protochlorophyllide a	700629	
1.14.13.81	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	700629	
1.14.13.81	malfunction	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	746223	
1.14.13.81	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	700629	
1.14.13.81	malfunction	Cth1 accumulates in copper-sufficient, oxygenated cells	700629	
1.14.13.81	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	745807