ArabidopsisFNRL protein is an NADPH‐dependent chloroplast oxidoreductase resembling bacterial ferredoxin‐NADP⁺reductases

Abstract

Plastidic ferredoxin-NADP oxidoreductases (FNRs; EC:1.18.1.2) together with bacterial type FNRs (FPRs) form the plant-type FNR family. Members of this group contain a two-domain scaffold that forms the basis of an extended superfamily of flavin adenine dinucleotide (FAD) dependent oxidoreductases. In this study, we show that the Arabidopsis thaliana At1g15140 [Ferredoxin-NADP oxidoreductase-like (FNRL)] is an FAD-containing NADPH dependent oxidoreductase present in the chloroplast stroma. Determination of the kinetic parameters using the DCPIP NADPH-dependent diaphorase assay revealed that the reaction catalysed by a recombinant FNRL protein followed a saturation Michaelis-Menten profile on the NADPH concentration with k = 3.2 ± 0.2 s , K = 1.6 ± 0.3 μM and k /K = 2.0 ± 0.4 μM s . Biochemical assays suggested that FNRL is not likely to interact with Arabidopsis ferredoxin 1, which is supported by the sequence analysis implying that the known Fd-binding residues in plastidic FNRs differ from those of FNRL. In addition, based on structural modelling FNRL has an FAD-binding N-terminal domain built from a six-stranded β-sheet and one α-helix, and a C-terminal NADP -binding α/β domain with a five-stranded β-sheet with a pair of α-helices on each side. The FAD-binding site is highly hydrophobic and predicted to bind FAD in a bent conformation typically seen in bacterial FPRs.

Plant responses to fungal volatiles involve global posttranslational thiol redox proteome changes that affect photosynthesis

“…PSAN is essential for efficient interaction between plastocyanin and P700 reaction centre of the PSI complex and thus participates in optimization of electron flow (Haldrup, Naver, & Scheller, ). FNRL is a FAD‐containing NADP + oxidoreductase likely involved in PET (Koskela et al, ). It is tempting to speculate that VC‐promoted ETR enhancement (Figure c) is at least partly due to reductive activation of PSAN and FNRL.…”

Comparative Proteomics of Salt-Tolerant and Salt-Sensitive Maize Inbred Lines to Reveal the Molecular Mechanism of Salt Tolerance

“…We found that cytochrome P450 11 (P45011) (tr|A0A1D6NI59) was also up-regulated in two maize inbred lines under salt stress, which may indicate that P450 11 is a salt stress active protein. Feredoxin NADP-dependent oxidoreductase (NADP-DOR) is a flavin adenine dinucleotide-binding enzyme, which is encoded by the small nuclear gene family and commonly found in higher plants [39]. In Populus simonii , NADP-DOR was up-regulated under abiotic stress [40].…”

Identification of novel differentially expressed zooxanthellal genes fromAiptasia-Symbiodiniumendosymbiosis through SDS-based RNA purification

“…Expression of chloroplast phosphoglycerate kinase was implicated in the downregulation of photosynthetic activity during glycolysis impairment for metabolic adjustment and to optimize growth [58]. Chloroplastic fucoxanthin-chlorophyll a-c binding protein F, cryptochrome-1 and NADPH-dependent diflavin oxidoreductase 1 were differentially expressed (Table 2), suggesting that light responses of zooxanthellae were mediated by cryptochrome-1 [59], NADPH-dependent diflavin oxidoreductase 1 catalysed the NADP-dependent reduction of cytochrome c, but not cytochrome P450 in vitro [60] and energy was transferred from the carotenoid and chlorophyll C (or B) to chlorophyll A and the photosynthetic reaction centres where chloroplastic Fucoxanthin-chlorophyll a-c binding protein F is used to synthesize ATP and reduce solar power [61]. Altogether, the present results indicate that zooxanthellae in the symbiotic stage had an enhanced photosynthetic efficiency, which was not observed in the nonsymbiotic stage.…”