Pyropheophorbide a, A catabolite of ethylene-induced chlorophyll a degradation

Shimokawa, Keishi; Hashizume, Akihito; Shioi, Yuzo

doi:10.1016/0031-9422(90)83014-r

Cited by 48 publications

(13 citation statements)

References 12 publications

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“…Several published reports have described accumulation of various green intermediates of chlorophyll breakdown, including phein and pyropheophytin (Schoch et al, 1981;Schoch and Vielwerth, 1983;Amir-Shapira et al, 1987). However, dephytylated pigments, such as chlide, pheide, and pyropheophorbide, have been found as well (Amir-Shapira et al, 1987;Ziegler et al, 1988;Shimokawa et al, 1990;Shioi et al, 1991;Roca et al, 2004). Identification of Mg-free pheo intermediates is in agreement with the proposed route, but accumulation of chlide would argue against it.…”

Section: Pph Is a Pheophytinase But Not A Chlorophyllasementioning

confidence: 57%

Pheophytin Pheophorbide Hydrolase (Pheophytinase) Is Involved in Chlorophyll Breakdown during Leaf Senescence in Arabidopsis

et al. 2009

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During leaf senescence, chlorophyll is removed from thylakoid membranes and converted in a multistep pathway to colorless breakdown products that are stored in vacuoles. Dephytylation, an early step of this pathway, increases water solubility of the breakdown products. It is widely accepted that chlorophyll is converted into pheophorbide via chlorophyllide. However, chlorophyllase, which converts chlorophyll to chlorophyllide, was found not to be essential for dephytylation in Arabidopsis thaliana. Here, we identify pheophytinase (PPH), a chloroplast-located and senescence-induced hydrolase widely distributed in algae and land plants. In vitro, Arabidopsis PPH specifically dephytylates the Mg-free chlorophyll pigment, pheophytin (phein), yielding pheophorbide. An Arabidopsis mutant deficient in PPH (pph-1) is unable to degrade chlorophyll during senescence and therefore exhibits a stay-green phenotype. Furthermore, pph-1 accumulates phein during senescence. Therefore, PPH is an important component of the chlorophyll breakdown machinery of senescent leaves, and we propose that the sequence of early chlorophyll catabolic reactions be revised. Removal of Mg most likely precedes dephytylation, resulting in the following order of early breakdown intermediates: chlorophyll / pheophytin / pheophorbide. Chlorophyllide, the last precursor of chlorophyll biosynthesis, is most likely not an intermediate of breakdown. Thus, chlorophyll anabolic and catabolic reactions are metabolically separated.

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Section: Pph Is a Pheophytinase But Not A Chlorophyllasementioning

confidence: 57%

Pheophytin Pheophorbide Hydrolase (Pheophytinase) Is Involved in Chlorophyll Breakdown during Leaf Senescence in Arabidopsis

et al. 2009

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“…Among the latter are pyro (=C13 2 -decarboxymethylated) forms of Pheide and pheophytin, which have been discussed as breakdown products of Chl in algae and higher plants (Schoch and Vielwerth, 1983;Ziegler et al, 1988;Shioi et al, 1991). In support of this finding was the demonstration of Pheide-to-pyro-Pheide conversion in enzyme extracts of different higher plants species, such as satsuma (Citrus unshiu) fruit peel and leaves of goosefoot (Chenopodium album) and different Brassicaceae species (Shimokawa et al, 1990;Suzuki et al, 2002). The enzyme, named pheophorbidase (PPD), was shown to only catalyze demethylation at the C13 2 -carboxymethyl group of Pheide to yield O13 4 -desmethyl Pheide, while the subsequent decarboxylation to form pyro-Pheide occurred spontaneously without the contribution of PPD (Shioi et al, 1996).…”

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confidence: 89%

MES16, a Member of the Methylesterase Protein Family, Specifically Demethylates Fluorescent Chlorophyll Catabolites during Chlorophyll Breakdown in Arabidopsis

et al. 2011

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During leaf senescence, chlorophyll (Chl) is broken down to nonfluorescent chlorophyll catabolites (NCCs). These arise from intermediary fluorescent chlorophyll catabolites (FCCs) by an acid-catalyzed isomerization inside the vacuole. The chemical structures of NCCs from Arabidopsis (Arabidopsis thaliana) indicate the presence of an enzyme activity that demethylates the C13 2 -carboxymethyl group present at the isocyclic ring of Chl. Here, we identified this activity as methylesterase family member 16 (MES16; At4g16690). During senescence, mes16 leaves exhibited a strong ultraviolet-excitable fluorescence, which resulted from large amounts of different FCCs accumulating in the mutants. As confirmed by mass spectrometry, these FCCs had an intact carboxymethyl group, which slowed down their isomerization to respective NCCs. Like a homologous protein cloned from radish (Raphanus sativus) and named pheophorbidase, MES16 catalyzed the demethylation of pheophorbide, an early intermediate of Chl breakdown, in vitro, but MES16 also demethylated an FCC. To determine the in vivo substrate of MES16, we analyzed pheophorbide a oxygenase1 (pao1), which is deficient in pheophorbide catabolism and accumulates pheophorbide in the chloroplast, and a mes16pao1 double mutant. In the pao1 background, we additionally mistargeted MES16 to the chloroplast. Normally, MES16 localizes to the cytosol, as shown by analysis of a MES16-green fluorescent protein fusion. Analysis of the accumulating pigments in these lines revealed that pheophorbide is only accessible for demethylation when MES16 is targeted to the chloroplast. Together, these data demonstrate that MES16 is an integral component of Chl breakdown in Arabidopsis and specifically demethylates Chl catabolites at the level of FCCs in the cytosol.

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“…After senescence under natural conditions, it accounts for more than 90% of the total NCCs accumulated in cotyledons [38]. Pyro Pheides have frequently been described as early catabolites of Chl degradation [18,22,23], and the enzyme involved was referred to as decarbomethoxylase [22,23]. It is constitutive and specifically accepts tetrapyrrolic Chl catabolites with a hydroxyl group at C(8 2 ) as substrates [108].…”

Section: Transition Of Pfcc Into Nccmentioning

confidence: 99%

Chlorophyll breakdown in higher plants and algae

Hörtensteiner¹

1999

Cellular and Molecular Life Sciences (CMLS)

136

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Leaf senescence is accompanied by the metabolism of chlorophyll (Chl) to nonfluorescent catabolites (NCCs). The pathway of Chl degradation comprises several reactions and includes the occurrence of intermediary catabolites. After removal of phytol and the central Mg atom from Chl by chlorophyllase and Mg dechelatase, respectively, the porphyrin macrocycle of pheophorbide (Pheide) a is cleaved. This two-step reaction is catalyzed by Pheide a oxygenase and RCC reductase and yields a primary fluorescent catabolite (pFCC). After hydroxylation and additional species-specific modifications, FCCs are tautomerized nonenzymically to NCCs inside the vacuole. Different subcellular compartments participate in Chl catabolism and, thus, transport processes across membranes are required. This review focuses on the catabolites and the individual reactions of Chl breakdown in higher plants. In addition, the pathway is compared to Chl conversion to red catabolites in an alga, Chlorella protothecoides. Finally, the significance and regulation of Chl degradation are discussed.

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Pyropheophorbide a, A catabolite of ethylene-induced chlorophyll a degradation

Cited by 48 publications

References 12 publications

Pheophytin Pheophorbide Hydrolase (Pheophytinase) Is Involved in Chlorophyll Breakdown during Leaf Senescence in Arabidopsis

Pheophytin Pheophorbide Hydrolase (Pheophytinase) Is Involved in Chlorophyll Breakdown during Leaf Senescence in Arabidopsis

MES16, a Member of the Methylesterase Protein Family, Specifically Demethylates Fluorescent Chlorophyll Catabolites during Chlorophyll Breakdown in Arabidopsis

Chlorophyll breakdown in higher plants and algae

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