Regulation of the Late Steps of Chlorophyll Biosynthesis

Rüdiger, Wolfhart

doi:10.1007/978-0-387-78518-9_16

Cited by 9 publications

(9 citation statements)

References 56 publications

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“…However, accumulation of such precursors, especially protoporphyrin IX, can lead to photosensitivity ( Inagaki et al, 2015 ). In the presence of light, the chlorophyll precursors with a porphyrin structure interact with triplet oxygen molecule to produce highly reactive singlet oxygen, which in turn can catalyze peroxidation of lipids and other cellular macromolecules ( Rüdiger, 2009 ). It has also been demonstrated that various porphyrin derivatives might have broad antiviral activity – however, the activity is mostly extracellular.…”

Section: Discussionmentioning

confidence: 99%

Infection by a Giant Virus (AaV) Induces Widespread Physiological Reprogramming in Aureococcus anophagefferens CCMP1984 – A Harmful Bloom Algae

2018

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While viruses with distinct phylogenetic origins and different nucleic acid types can infect and lyse eukaryotic phytoplankton, “giant” dsDNA viruses have been found to be associated with important ecological processes, including the collapse of algal blooms. However, the molecular aspects of giant virus–host interactions remain largely unknown. Aureococcus anophagefferens virus (AaV), a giant virus in the Mimiviridae clade, is known to play a critical role in regulating the fate of brown tide blooms caused by the pelagophyte Aureococcus anophagefferens. To understand the physiological response of A. anophagefferens CCMP1984 upon AaV infection, we studied the transcriptomic landscape of this host–virus pair over an entire infection cycle using a RNA-sequencing approach. A massive transcriptional response of the host was evident as early as 5 min post-infection, with modulation of specific processes likely related to both host defense mechanism(s) and viral takeover of the cell. Infected Aureococcus showed a relative suppression of host-cell transcripts associated with photosynthesis, cytoskeleton formation, fatty acid, and carbohydrate biosynthesis. In contrast, host cell processes related to protein synthesis, polyamine biosynthesis, cellular respiration, transcription, and RNA processing were overrepresented compared to the healthy cultures at different stages of the infection cycle. A large number of redox active host-selenoproteins were overexpressed, which suggested that viral replication and assembly progresses in a highly oxidative environment. The majority (99.2%) of annotated AaV genes were expressed at some point during the infection cycle and demonstrated a clear temporal–expression pattern and an increasing relative expression for the majority of the genes through the time course. We detected a putative early promoter motif for AaV, which was highly similar to the early promoter elements of two other Mimiviridae members, indicating some degree of evolutionary conservation of gene regulation within this clade. This large-scale transcriptome study provides insights into the Aureococcus cells infected by a giant virus and establishes a foundation to test hypotheses regarding metabolic and regulatory processes critical for AaV and other Mimiviridae members.

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Section: Discussionmentioning

confidence: 99%

Infection by a Giant Virus (AaV) Induces Widespread Physiological Reprogramming in Aureococcus anophagefferens CCMP1984 – A Harmful Bloom Algae

2018

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“…The heat-induced cotyledon bleaching of cld1-1 seedlings could be attributed to the accumulation of Chlide a ( Figure 6A), which is potent in generating reactive oxygen species light-dependently (Lin et al, 2014). Because the HS treatment was performed in the dark, the Chlide a level accumulated in the mutant seedlings was unlikely derived from the de novo light-dependent reduction of protochlorophyllide, which is catalyzed by NADPH:protochlorophyllide oxidoreductase (Rüdiger, 2009). Hence, the accumulation of Chlide a should result from the dephytylation of chlorophyll a catalyzed by CLD1 in vivo.…”

Section: Cld1 Is Involved In Chlorophyll Turnover At Steady Statementioning

confidence: 99%

“…Several intermediates of chlorophyll metabolism are photosensitizers that can induce oxidative stress (Rüdiger, 2009), so their accumulation must be avoided under all conditions. Genetic mutants that conditionally accumulate these intermediates are useful in deciphering the complex and highly regulated pathways in chlorophyll metabolism (Kusaba et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Identification of a Chlorophyll Dephytylase Involved in Chlorophyll Turnover in Arabidopsis

Lin

Charng

2016

Plant Cell

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Chlorophyll turns over in green organs during photosystem repair and is salvaged via de-and rephytylation, but the enzyme involved in dephytylation is unknown. We have identified an Arabidopsis thaliana thylakoid protein with a putative hydrolase domain that can dephytylate chlorophyll in vitro and in vivo. The corresponding locus, CHLOROPHYLL DEPHYTYLASE1 (CLD1), was identified by mapping a semidominant, heat-sensitive, missense allele (cld1-1). CLD1 is conserved in oxygenic photosynthetic organisms, sharing structural similarity with pheophytinase, which functions in chlorophyll breakdown during leaf senescence. Unlike pheophytinase, CLD1 is predominantly expressed in green organs and can dephytylate chlorophyll in vitro. The specific activity is significantly higher for the mutant protein encoded by cld1-1 than the wild-type enzyme, consistent with the semidominant nature of the cld1-1 mutation. Supraoptimal CLD1 activities in cld1-1 mutants and transgenic seedlings led to the proportional accumulation of chlorophyllides derived from chlorophyll dephytylation after heat shock, which resulted in light-dependent cotyledon bleaching. Reducing CLD1 expression diminished thermotolerance and the photochemical efficiency of photosystem II under prolonged moderate heat stress. Taken together, our results suggest that CLD1 is the long-sought enzyme for removing the phytol chain from chlorophyll during its turnover at steady state within the chloroplast.

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“…Chlide esterification catalyzed by chlorophyll synthase is the last step in Chl biosynthesis (reviewed in [83,84]). The addition of the diterpene side chain to the C17 propyl moiety of Chlide only slightly influences the spectral properties of the pigment and its photophysical properties [41], although it increases the lipophilicity of the product.…”

Section: Fig (2)mentioning

confidence: 99%

“…Similarly, the accumulation of 'free' or not properly bound Chl precursors (e.g., Pchlide [74,[101][102][103]190]) and Chl derivatives has photosensitizing effect in plant tissues. Therefore, the level of these pigments and their organization in vivo is strictly regulated in plants [20,50,74,84]. Taken together, special care has to be taken during animal feed production.…”

Section: Table 2 Medicinal Use Of Different Chl Derivatives In Photomentioning

confidence: 99%

Chlorophylls and their Derivatives Used in Food Industry and Medicine

Solymosi

Myśliwa-Kurdziel

2017

MRMC

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Regulation of the Late Steps of Chlorophyll Biosynthesis

Cited by 9 publications

References 56 publications

Infection by a Giant Virus (AaV) Induces Widespread Physiological Reprogramming in Aureococcus anophagefferens CCMP1984 – A Harmful Bloom Algae

Infection by a Giant Virus (AaV) Induces Widespread Physiological Reprogramming in Aureococcus anophagefferens CCMP1984 – A Harmful Bloom Algae

Identification of a Chlorophyll Dephytylase Involved in Chlorophyll Turnover in Arabidopsis

Chlorophylls and their Derivatives Used in Food Industry and Medicine

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