scholarly journals NADPH: Protochlorophyllide Oxidoreductase-Structure, Catalytic Function, and Role in Prolamellar Body Formation and Morphogenesis

2013 ◽  
Author(s):  
Michael P Timko
Keyword(s):  
Prolamellar Body ◽  
Protochlorophyllide Oxidoreductase ◽  
Body Formation ◽  
Catalytic Function

scholarly journals A cis-carotene derived apocarotenoid regulates etioplast and chloroplast development

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Christopher I Cazzonelli ◽  
Xin Hou ◽  
Yagiz Alagoz ◽  
John Rivers ◽  
Namraj Dhami ◽  
...  
Keyword(s):  
Carotenoid Biosynthesis ◽  
Forward Genetics ◽  
Regulatory Function ◽  
Prolamellar Body ◽  
Carotenoid Cleavage Dioxygenase ◽  
Protochlorophyllide Oxidoreductase ◽  
Plastid Development ◽  
Dark Light ◽  
Light Regimes ◽  
Protein Levels

Carotenoids are a core plastid component and yet their regulatory function during plastid biogenesis remains enigmatic. A unique carotenoid biosynthesis mutant, carotenoid chloroplast regulation 2 (ccr2), that has no prolamellar body (PLB) and normal PROTOCHLOROPHYLLIDE OXIDOREDUCTASE (POR) levels, was used to demonstrate a regulatory function for carotenoids and their derivatives under varied dark-light regimes. A forward genetics approach revealed how an epistatic interaction between a ζ-carotene isomerase mutant (ziso-155) and ccr2 blocked the biosynthesis of specific cis-carotenes and restored PLB formation in etioplasts. We attributed this to a novel apocarotenoid retrograde signal, as chemical inhibition of carotenoid cleavage dioxygenase activity restored PLB formation in ccr2 etioplasts during skotomorphogenesis. The apocarotenoid acted in parallel to the repressor of photomorphogenesis, DEETIOLATED1 (DET1), to transcriptionally regulate PROTOCHLOROPHYLLIDE OXIDOREDUCTASE (POR), PHYTOCHROME INTERACTING FACTOR3 (PIF3) and ELONGATED HYPOCOTYL5 (HY5). The unknown apocarotenoid signal restored POR protein levels and PLB formation in det1, thereby controlling plastid development.

scholarly journals Secondary structure of NADPH: protochlorophyllide oxidoreductase examined by circular dichroism and prediction methods*

1996 ◽  
Vol 317 (2) ◽  
pp. 549-555 ◽  
Author(s):  
Simon J. BIRVE ◽  
Eva SELSTAM ◽  
Lennart B.-Å. JOHANSSON
Keyword(s):  
Secondary Structure ◽  
Fluorescence Emission ◽  
Random Coil ◽  
Prolamellar Body ◽  
Interfacial Region ◽  
Protochlorophyllide Oxidoreductase ◽  
Loop Region ◽  
Rossmann Fold ◽  
Α Helix ◽  
Β Sheet

To study the secondary structure of the enzyme NADPH: protochlorophyllide oxidoreductase (PCOR), a novel method of enzyme isolation was developed. The detergent isotridecyl poly(ethylene glycol) ether (Genapol X-080) selectively solubilizes the enzyme from a prolamellar-body fraction isolated from wheat (Triticum aestivumL.). The solubilized fraction was further purified by ion-exchange chromatography. The isolated enzyme was studied by fluorescence spectroscopy at 77 K, and by CD spectroscopy. The fluorescence-emission spectra revealed that the binding properties of the substrate and co-substrate were preserved and that photo-reduction occurred. The CD spectra of PCOR were analysed for the relative amounts of the secondary structures, α-helix, β-sheet, turn and random coil. The secondary-structure composition was estimated to be 33% α-helix, 19% β-sheet, 20% turn and 28% random coil. These values are in agreement with those predicted by the Predict Heidelberg Deutschland and self-optimized prediction method from alignments methods. The enzyme has some amino acid identity with other NADPH-binding enzymes containing the Rossmann fold. The Rossmann-fold fingerprint motif is localized in the N-terminal region and at the expected positions in the predicted secondary structure. It is suggested that PCOR is anchored to the interfacial region of the membrane by either a β-sheet or an α-helical region containing tryptophan residues. A hydrophobic loop-region could also be involved in membrane anchoring.

scholarly journals A cis-carotene derived apocarotenoid regulates etioplast and chloroplast development

2019 ◽  
Author(s):  
Christopher I Cazzonelli ◽  
Xin Hou ◽  
Yagiz Alagoz ◽  
John Rivers ◽  
Namraj Dhami ◽  
...  
Keyword(s):  
Chloroplast Development ◽  
Carotenoid Biosynthesis ◽  
Forward Genetics ◽  
Regulatory Function ◽  
Prolamellar Body ◽  
Carotenoid Cleavage Dioxygenase ◽  
Protochlorophyllide Oxidoreductase ◽  
Plastid Development ◽  
Dark Light ◽  
Protein Levels

ABSTRACTCarotenoids are core plastid components, yet a regulatory function during plastid biogenesis remains enigmatic. A unique carotenoid biosynthesis mutant, carotenoid chloroplast regulation 2 (ccr2), that has no prolamellar body (PLB) and normal PROTOCHLOROPHYLLIDE OXIDOREDUCTASE (POR) levels, was used to demonstrate a regulatory function for carotenoids under varied dark-light regimes. A forward genetics approach revealed how an epistatic interaction between a (-carotene isomerase mutant (ziso-155) and ccr2 blocked the biosynthesis of specific cis-carotenes and restored PLB formation in etioplasts. We attributed this to a novel apocarotenoid signal, as chemical inhibition of carotenoid cleavage dioxygenase activity restored PLB formation in ccr2 etioplasts during skotomorphogenesis. The apocarotenoid acted in parallel to the transcriptional repressor of photomorphogenesis, DEETIOLATED1 (DET1), to post-transcriptionally regulate PROTOCHLOROPHYLLIDE OXIDOREDUCTASE (POR), PHYTOCHROME INTERACTING FACTOR3 (PIF3) and ELONGATED HYPOCOTYL5 (HY5) protein levels. The apocarotenoid signal and det1 complemented each other to restore POR levels and PLB formation, thereby controlling plastid development.One-sentence summaryCarotenoids are not just required as core components for plastid biogenesis, they can be cleaved into an apocarotenoid signal that regulates etioplast and chloroplast development during extended periods of darkness.

Curvature thylakoid 1 proteins modulate prolamellar body morphology and promote organized thylakoid biogenesis in Arabidopsis thaliana

2021 ◽  
Vol 118 (42) ◽  
pp. e2113934118
Author(s):  
Omar Sandoval-Ibáñez ◽  
Anurag Sharma ◽  
Michał Bykowski ◽  
Guillem Borràs-Gas ◽  
James B. Y. H. Behrendorff ◽  
...  
Keyword(s):  
Thylakoid Membrane ◽  
Critical Role ◽  
Land Plants ◽  
Prolamellar Body ◽  
Protochlorophyllide Oxidoreductase ◽  
Pigment Composition ◽  
Thylakoid Biogenesis ◽  
Bending Capacity ◽  
Photosynthetic Complexes ◽  
Membrane Bending

The term “de-etiolation” refers to the light-dependent differentiation of etioplasts to chloroplasts in angiosperms. The underlying process involves reorganization of prolamellar bodies (PLBs) and prothylakoids into thylakoids, with concurrent changes in protein, lipid, and pigment composition, which together lead to the assembly of active photosynthetic complexes. Despite the highly conserved structure of PLBs among land plants, the processes that mediate PLB maintenance and their disassembly during de-etiolation are poorly understood. Among chloroplast thylakoid membrane–localized proteins, to date, only Curvature thylakoid 1 (CURT1) proteins were shown to exhibit intrinsic membrane-bending capacity. Here, we show that CURT1 proteins, which play a critical role in grana margin architecture and thylakoid plasticity, also participate in de-etiolation and modulate PLB geometry and density. Lack of CURT1 proteins severely perturbs PLB organization and vesicle fusion, leading to reduced accumulation of the light-dependent enzyme protochlorophyllide oxidoreductase (LPOR) and a delay in the onset of photosynthesis. In contrast, overexpression of CURT1A induces excessive bending of PLB membranes, which upon illumination show retarded disassembly and concomitant overaccumulation of LPOR, though without affecting greening or the establishment of photosynthesis. We conclude that CURT1 proteins contribute to the maintenance of the paracrystalline PLB morphology and are necessary for efficient and organized thylakoid membrane maturation during de-etiolation.

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