1.3.7.7 evolution cyanobacteria, algae, bryophytes, pteridophytes and gymnosperms use an additional, light-independent enzyme dubbed dark-operative Pchlide oxidoreductase for chlorophyll biosynthesis, besides a light-dependent enzyme, mechanisms of protochlorophyllide a reduction in photosynthetic organisms, ooverview 726526 1.3.7.7 evolution cyanobacteria, algae, bryophytes, pteridophytes and gymnosperms use an additional, light-independent enzyme dubbed dark-operative Pchlide oxidoreductase for chlorophyll biosynthesis, besides a light-dependent enzyme, mechanisms of protochlorophyllide a reduction in photosynthetic organisms, overview 726526 1.3.7.7 evolution protein-protein interaction surfaces for transition state complexes of DPOR and nitrogenase, using PDB ID code 1M34, analysis of catalytic differences and similarities between DPOR and nitrogenase, overview 726394 1.3.7.7 evolution the enzyme is involved in the biosynthesis of chlorophylls and bacteriochlorophylls in gymnosperm, ferns, algae, and photosynthetic bacteria 725877 1.3.7.7 malfunction a strain lacking DPOR contains about 25% of the wild-type level of photosystems PSII and PSI when cultivated under light-activated heterotrophic growth conditions. Deletion of the chlL gene abolishes activity of the DPOR enzyme. Absence of the chlL gene causes a further 20% decrease in Chl content and therefore the resulting (pCER:por)/Dpor/DchlL strain termed SynPORreg reaches only 60-70% of Chl content present in wild-type 726255 1.3.7.7 metabolism chlorophyll biosynthesis is catalyzed by two multi subunit enzymes; a light-dependent and a light-independent protochlorophyllide oxidoreductase 725926 1.3.7.7 metabolism protochlorophyllide reduction is a key regulatory step in Chl biosynthesis 726104 1.3.7.7 metabolism the three-subunit enzyme dubbed DPOR operates in the synthesis of Bchls a, b, and g 726526 1.3.7.7 metabolism two independent enzymes catalyze the reduction of protochlorophyllide to chlorophyllide, which is the penultimate step in chlorophyll biosynthesis. One is light-dependent NADPH:protochlorophyllide oxidoreductase and the second type is dark-operative protochlorophyllide oxidoreductase 726255 1.3.7.7 additional information dark-grown seedlings of Pinus mugo accumulate chlorophyll and its precursor protochlorophyllide 726104 1.3.7.7 additional information dark-grown seedlings of Pinus sylvestris accumulate chlorophyll and its precursor protochlorophyllide 726104 1.3.7.7 additional information some purple bacteria contain Bchl b, and heliobacteria such as Heliobacillus mobilis contain Bchl g, as compared to Chl a and Chl b of higher plants 726526 1.3.7.7 additional information the homodimeric subunit ChlL2 transfers electrons to the corresponding heterotetrameric catalytic subunit (ChlN/ChlB)2, transfer of a single electron from the [4Fe-4S] cluster of ChlL2 onto a second [4Fe-4S] cluster located on (ChlN/ChlB)2 725877 1.3.7.7 additional information the organism contains another type of Chl, bacteriochlorophyll (Bchl) a, as compared to Chl a and Chl b of higher plants 726526 1.3.7.7 additional information the organism contains another type of Chl, bacteriochlorophyll (Bchl) a, as compared to Chl a and Chl b of higher plants. Residue Asp36 is not necessary for enzyme complex formation but for enzyme activity. Subunit BchB possesses a unique C-terminal region consisting of approximately 100 amino acid residues (Phe422-Arg525), which is probably important for protochlorophyllide reduction 726526 1.3.7.7 additional information transient protein-protein interaction of ChlL2 and (ChlN/ChlB)2 is essential for the ATP-dependent electron transfer processes catalyzed by DPOR. Efficient octameric (ChlN/ChlB)2(ChlL2)2 enzyme complex formation required the presence of protochlorophyllide. Complete ATP hydrolysis is a prerequisite for intersubunit electron transfer 725412 1.3.7.7 additional information upon complex formation, substantial ATP-dependent conformational rearrangements of L2 trigger the protein-protein interactions with (NB)2 as well as the electron transduction via redox-active [4Fe-4S] clusters, dynamic interplay between L2 and (NB)2. Asp155 is responsible for positioning and/or activating a specific water molecule for the subsequent ATP hydrolysis, whereas Lys37 of the P-loop possibly assists the release of gamma-phosphate upon ATP hydrolysis 726394 1.3.7.7 physiological function DPOR is a determinant enzyme for greening ability in the dark 713252 1.3.7.7 physiological function DPOR performs reduction of the C17-C18 double bond of protochlorophyllide to form chlorophyllide a, the direct precursor of chlorophyll a in a light-independent, dark-operative way of action -, 713102 1.3.7.7 physiological function DPOR plays a key role in the ability to synthesize chlorophyll in darkness 712984 1.3.7.7 physiological function during chlorophyll biosynthesis in photosynthetic bacteria, cyanobacteria, green algae and gymnosperms, dark-operative protochlorophyllide oxidoreductase, a nitrogenase-like metalloenzyme, catalyzes the chemically challenging two-electron reduction of the fully conjugated ring system of protochlorophyllide a. The reduction of the C-17=C-18 double bond results in the characteristic ring architecture of all chlorophylls, thereby altering the absorption properties of the molecule and providing the basis for light-capturing and energytransduction processes of photosynthesis 726394 1.3.7.7 physiological function light-independent protochlorophyllide reductase is required for protochlorophyllide reduction in the dark 672764 1.3.7.7 physiological function the expression of NADPH:protochlorophyllide oxidoreductase A (PorA), PorB, and PorC, which catalyze a key step in chlorophyll biosynthesis, is increased in the BRM mutants, defective in a SWI2/SNF2 chromatin-remodeling ATPase 743315