Light-Dependent Protochlorophyllide Oxidoreductase: Phylogeny, Regulation, and Catalytic Properties

Abstract

This Current Topic focuses on light-dependent protochlorophyllide oxidoreductase (POR, EC 1.3.1.33). POR catalyzes the penultimate reaction of chlorophyll biosynthesis, i.e., the light-triggered reduction of protochlorophyllide to chlorophyllide. In this reaction, the chlorin ring of the chlorophyll molecule is formed, which is crucial for photosynthesis. POR is one of very few enzymes that are driven by light; however, it is unique in the need for its substrate to absorb photons to induce the conformational changes in the enzyme, which are required for its catalytic activation. Moreover, the enzyme is also involved in the negative feedback of the chlorophyll biosynthesis pathway and controls chlorophyll content via its light-dependent activity. Even though it has been almost 70 years since the first isolation of active POR complexes, our knowledge of them has markedly advanced in recent years. In this review, we summarize the current state of knowledge of POR, including the phylogenetic roots of POR, the mechanisms of the regulation of POR genes expression, the regulation of POR activity, the import of POR into plastids, the role of POR in PLB formation, and the molecular mechanism of protochlorophyllide reduction by POR. To the best of our knowledge, no previous review has compiled such a broad set of recent findings about POR.

Altered gene expression by sedaxane increases PSII efficiency, photosynthesis and growth and improves tolerance to drought in wheat seedlings

“…Fungicides of the class of succinate dehydrogenase complex II inhibitors (SDHIs) however 57 have been recently shown to significantly increase the efficiency of PSII photochemistry 58 maintained at the same available water until the end of the experiment. Experiment 2 was 128 designed as randomized block with two treatments, sedaxane or untreated and consisted of 129 22 replicates, seven of which were considered as indicator plants while samples for RNA 130 isolation were collected from the remaining 15 replicates.…”

Translation and Co-translational Membrane Engagement of Plastid-encoded Chlorophyll-binding Proteins Are Not Influenced by Chlorophyll Availability in Maize

“…Hence, the synthesis of chlorophylls is coordinated with the availability of chlorophyll-binding apoproteins (Wang and Grimm, 2015). Chlorophyll synthesis is regulated at different steps and activated by light (Brzezowski et al, 2015; Gabruk and Mysliwa-Kurdziel, 2015). In turn, the expression of the nuclear-encoded LHC apoproteins is adjusted by retrograde chloroplast-to-nucleus signaling, which has been suggested to emanate, among other origins, from intermediates in chlorophyll synthesis (Kleine and Leister, 2016; Larkin, 2016).…”

Biocatalysis Fueled by Light: On the Versatile Combination of Photocatalysis and Enzymes

“…Another family of photoenzymes is that of DNA photolyases, the function of which consists of the repair of UV‐induced lesions in DNA. Light‐dependent photochlorophyllidine oxidoreductases (LPORs) are NADPH‐dependent photoenzymes that are involved in chlorophyll synthesis by converting protochlorophyllide into chlorophyllide a . Chlorophyll f synthase might be considered another type of photoenzyme, catalyzing the four‐electron photooxidation of chlorophyll a to chlorophyll f. The light‐dependence of this reaction, however, is yet not fully elucidated.…”

“…Light-dependent photochlorophyllidine oxidoreductases (LPORs) are NADPH-dependent photoenzymes that are involved in chlorophyll synthesis by converting protochlorophyllide into chlorophyllide a. [97] Chlorophyll fs ynthase [98] might be considered another type of photoenzyme, catalyzing the four-electron photooxidationo f chlorophyll at oc hlorophyll f. Thel ight-dependence of this reaction, however,isy et not fully elucidated. Recently,B eissona nd co-workers reported on an ew photoenzyme from the microalga Chlorella variabilis NC64A that catalyzes decarboxylations of fatty acids 72 in response to blue light (400-520nm).…”