Chlorophyll
 a
 oxygenase (
 CAO
 ) is involved in chlorophyll
 b
 formation from chlorophyll
 a

Tanaka, Ayumi; Itô, Hisashi; Tanaka, Ryouichi; Tanaka, Nobuaki; Yoshida, Kanako; Okada, Kiyotaka

doi:10.1073/pnas.95.21.12719

Cited by 398 publications

(259 citation statements)

References 26 publications

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“…POR catalyzes the light-dependent reduction of protochlorophyllide a to chlorophyllide a, which is subsequently converted into chlorophyllide b by CAO [56][57][58][59]. The Arabidopsis genome has a single-copied CAO gene and three structurally related POR genes (A, B and C), of which only PORB is expressed throughout most developmental Cell Research | www.cell-research.com…”

Section: Chlorophyll Biosynthesis Is Downregulated In Spc1mentioning

confidence: 99%

The Arabidopsis Spontaneous Cell Death1 gene, encoding a ζ-carotene desaturase essential for carotenoid biosynthesis, is involved in chloroplast development, photoprotection and retrograde signalling

et al. 2007

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Carotenoids, a class of natural pigments found in all photosynthetic organisms, are involved in a variety of physiological processes, including coloration, photoprotection, biosynthesis of abscisic acid (ABA) and chloroplast biogenesis. Although carotenoid biosynthesis has been well studied biochemically, the genetic basis of the pathway is not well understood. Here, we report the characterization of two allelic Arabidopsis mutants, spontaneous cell death1-1 (spc1-1) and spc1-2. The weak allele spc1-1 mutant showed characteristics of bleached leaves, accumulation of superoxide and mosaic cell death. The strong mutant allele spc1-2 caused a complete arrest of plant growth and development shortly after germination, leading to a seedling-lethal phenotype. Genetic and molecular analyses indicated that SPC1 encodes a putative z-carotene desaturase (ZDS) in the carotenoid biosynthesis pathway. Analysis of carotenoids revealed that several major carotenoid compounds downstream of SPC1/ZDS were substantially reduced in spc1-1, suggesting that SPC1 is a functional ZDS. Consistent with the downregulated expression of CAO and PORB, the chlorophyll content was decreased in spc1-1 plants. In addition, expression of Lhcb1.1, Lhcb1.4 and RbcS was absent in spc1-2, suggesting the possible involvement of carotenoids in the plastid-to-nucleus retrograde signaling. The spc1-1 mutant also displays an ABA-deficient phenotype that can be partially rescued by the externally supplied phytohormone. These results suggest that SPC1/ZDS is essential for biosynthesis of carotenoids and plays a crucial role in plant growth and development.

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Section: Chlorophyll Biosynthesis Is Downregulated In Spc1mentioning

confidence: 99%

The Arabidopsis Spontaneous Cell Death1 gene, encoding a ζ-carotene desaturase essential for carotenoid biosynthesis, is involved in chloroplast development, photoprotection and retrograde signalling

et al. 2007

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“…For this purpose, we identi®ed the gene involved in Chl b biosynthesis in Chlamydomonas reinhardtii (Tanaka et al, 1998). The gene encoded a novel oxygenase with a Rieske-type [2Fe-2S] cluster and a mononuclear iron-binding site.…”

Section: Introductionmentioning

confidence: 99%

Overexpression of chlorophyllide a oxygenase (CAO) enlarges the antenna size of photosystem II in Arabidopsis thaliana

et al. 2001

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SummaryThe light-harvesting ef®ciency of a photosystem is thought to be largely dependent on its photosynthetic antenna size. It has been suggested that antenna size is controlled by the biosynthesis of chlorophyll b. To verify this hypothesis, we overexpressed the enzyme for chlorophyll b biosynthesis, chlorophyllide a oxygenase (CAO), in Arabidopsis thaliana by transforming the plant with cDNA for CAO under the control of the 35S cauli¯ower mosaic virus promoter. In the early de-etiolation phase, when the intrinsic CAO expression is very low, the chlorophyll a : b ratio was drastically decreased from 28 to 7.3, indicating that enhancement of chlorophyll b biosynthesis had been successfully achieved. We made the following observations in full-green rosette leaves of transgenic plants.(1) The chlorophyll a : b ratio was reduced from 2.85 to 2.65. (2) The ratio of the peripheral light-harvesting complexes (LHCII) to the core antenna complex (CPa) resolved with the green-gel system increased by 20%. (3) The ratio of the light-harvesting complex II apoproteins (LHCP) to 47-kDa chlorophyll a protein (CP47), which was estimated by the results of immunoblotting, increased by 40%. These results indicated that the antenna size increased by at least 10±20% in transgenic plants, suggesting that chlorophyll b biosynthesis controls antenna size. To the best of our knowledge, this is the ®rst report on enlargement of the antenna size by genetic manipulations.

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“…The Arabidopsis genome encodes five Riesketype oxygenases (Gray et al, 2004), all of which have been shown to localize to chloroplasts (Rathinasabapathi et al, 1997;Tanaka et al, 1998;Bartsch et al, 2008). In addition, three of them, PAO (At3g44880), TIC55 (At2g24820), and PTC52 (At4g25650), possess predicted C-terminally located transmembrane domains ( Figure 5A) that likely anchor these proteins to plastid membranes, while the other two Rieske-type oxygenases in Arabidopsis, chlorophyll a oxygenase (At1g44446) and choline monooxygenase (CMO)-like (At4g29890) are predicted to be soluble proteins (Tusnády and Simon, 2001).…”

Section: Hydroxy-pfcc Is Present In Gerontoplasts Of Arabidopsismentioning

confidence: 99%

A Role for TIC55 as a Hydroxylase of Phyllobilins, the Products of Chlorophyll Breakdown during Plant Senescence

et al. 2016

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ORCID IDs: 0000-0002-0044-0490 (M.H.); 0000-0002-7598-3609 (S.A.) Chlorophyll degradation is the most obvious hallmark of leaf senescence. Phyllobilins, linear tetrapyrroles that are derived from opening of the chlorin macrocycle by the Rieske-type oxygenase PHEOPHORBIDE a OXYGENASE (PAO), are the end products of chlorophyll degradation. Phyllobilins carry defined modifications at several peripheral positions within the tetrapyrrole backbone. While most of these modifications are species-specific, hydroxylation at the C3 2 position is commonly found in all species analyzed to date. We demonstrate that this hydroxylation occurs in senescent chloroplasts of Arabidopsis thaliana. Using bell pepper (Capsicum annuum) chromoplasts, we establish that phyllobilin hydroxylation is catalyzed by a membrane-bound, molecular oxygen-dependent, and ferredoxin-dependent activity. As these features resemble the requirements of PAO, we considered membrane-bound Rieske-type oxygenases as potential candidates. Analysis of mutants of the two Arabidopsis Rieske-type oxygenases (besides PAO) uncovered that phyllobilin hydroxylation depends on TRANSLOCON AT THE INNER CHLOROPLAST ENVELOPE55 (TIC55). Our work demonstrates a catalytic activity for TIC55, which in the past has been considered as a redox sensor of protein import into plastids. Given the wide evolutionary distribution of both PAO and TIC55, we consider that chlorophyll degradation likely coevolved with land plants.

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Chlorophyll a oxygenase ( CAO ) is involved in chlorophyll b formation from chlorophyll a

Cited by 398 publications

References 26 publications

The Arabidopsis Spontaneous Cell Death1 gene, encoding a ζ-carotene desaturase essential for carotenoid biosynthesis, is involved in chloroplast development, photoprotection and retrograde signalling

The Arabidopsis Spontaneous Cell Death1 gene, encoding a ζ-carotene desaturase essential for carotenoid biosynthesis, is involved in chloroplast development, photoprotection and retrograde signalling

Overexpression of chlorophyllide a oxygenase (CAO) enlarges the antenna size of photosystem II in Arabidopsis thaliana

A Role for TIC55 as a Hydroxylase of Phyllobilins, the Products of Chlorophyll Breakdown during Plant Senescence

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