Chlorophyll breakdown in higher plants and algae

Hörtensteiner, Stefan

doi:10.1007/s000180050434

Cited by 136 publications

(69 citation statements)

References 164 publications

(233 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…While the presence of an isoprenoid kinase for phytol activation was previously discussed Hö rtensteiner, 1999), it appears to be generally accepted that direct reduction of GGDP to PDP by GGR is the main pathway for the formation of (A) Multiple alignments were visualized and edited using GeneDoc (Nicholas et al, 1997). The residues are shaded using conserved residue shading mode set to level 4 using default settings.…”

Section: Discussionmentioning

confidence: 99%

“…While the subsequent fate of the chlorophyll breakdown product chlorophyllide a and its derived pigments has been well characterized, little is known about the metabolic fate of phytol (for general reviews on chlorophyll catabolism, see Hö rtensteiner, 1999;Matile et al, 1999;Krä utler, 2002). Phytol derived from chlorophyll breakdown is reesterified to acetic acid or other fatty acids (Peisker et al, 1989;Patterson et al, 1993), while a portion is also irreversibly destroyed by photodegradation (Rontani et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

TheArabidopsis vitamin E pathway gene5-1Mutant Reveals a Critical Role for Phytol Kinase in Seed Tocopherol Biosynthesis

Lincoln²,

et al. 2005

View full text Add to dashboard Cite

We report the identification and characterization of a low tocopherol Arabidopsis thaliana mutant, vitamin E pathway gene5-1 (vte5-1), with seed tocopherol levels reduced to 20% of the wild type. Map-based identification of the responsible mutation identified a G!A transition, resulting in the introduction of a stop codon in At5g04490, a previously unannotated gene, which we named VTE5. Complementation of the mutation with the wild-type transgene largely restored the wild-type tocopherol phenotype. A knockout mutation of the Synechocystis sp PCC 6803 VTE5 homolog slr1652 reduced Synechocystis tocopherol levels by 50% or more. Bioinformatic analysis of VTE5 and slr1652 indicated modest similarity to dolichol kinase. Analysis of extracts from Arabidopsis and Synechocystis mutants revealed increased accumulation of free phytol. Heterologous expression of these genes in Escherichia coli supplemented with free phytol and in vitro assays of recombinant protein produced phytylmonophosphate, suggesting that VTE5 and slr1652 encode phytol kinases. The phenotype of the vte5-1 mutant is consistent with the hypothesis that chlorophyll degradation-derived phytol serves as an important intermediate in seed tocopherol synthesis and forces reevaluation of the role of geranylgeranyl diphosphate reductase in tocopherol biosynthesis.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

TheArabidopsis vitamin E pathway gene5-1Mutant Reveals a Critical Role for Phytol Kinase in Seed Tocopherol Biosynthesis

Lincoln²,

et al. 2005

View full text Add to dashboard Cite

show abstract

“…The low Chl content per protein makes it unlikely that WSCPs are involved in the light reaction of photosynthesis. Meanwhile, it has been speculated (7,8) that WSCP acts as a scavenger of free Chl, by transporting it from the thylakoid membrane to the chloroplast envelope, where Chlase, the enzyme that initiates the Chl catabolism, is thought to reside (9).…”

mentioning

confidence: 99%

Structural Mechanism and Photoprotective Function of Water-soluble Chlorophyll-binding Protein

Horigome

Satoh²,

Itoh

et al. 2007

Journal of Biological Chemistry

108

216

View full text Add to dashboard Cite

A water-soluble chlorophyll-binding protein (WSCP) is the single known instance of a putative chlorophyll (Chl) carrier in green plants. Recently the photoprotective function of WSCP has been demonstrated by EPR measurements; the light-induced singlet-oxygen formation of Chl in the WSCP tetramer is about four times lower than that of unbound Chl. This paper describes the crystal structure of the WSCP-Chl complex purified from leaves of Lepidium virginicum (Virginia pepperweed) to clarify the mechanism of its photoprotective function. The WSCP-Chl complex is a homotetramer comprising four protein chains of 180 amino acids and four Chl molecules. At the center of the complex one hydrophobic cavity is formed in which all of the four Chl molecules are tightly packed and isolated from bulk solvent. With reference to the novel Chl-binding mode, we propose that the photoprotection mechanism may be based on the inhibition of physical contact between the Chl molecules and molecular oxygen.Water-soluble chlorophyll-binding proteins (WSCPs), 4 which form a complex with chlorophyll (Chl), have been isolated from Amaranthaceae, Chenopodiaceae, and Polygonaceae (class-I) and from Brassicaceae (class-II). The two WSCP classes differ in that the protein-Chl complexes of the former change their absorption spectra upon illumination, whereas those of the latter show no photoconversion of their absorption behavior (2). The amino acid sequence of class-I WSCP shows no similarity to that of class-II WSCP.The class-II WSCPs (hereafter referred to as "WSCPs") are water-soluble proteins of ϳ20 kDa, which form a tetrameric assembly upon binding Chl molecules with a Chl-to-protein ratio of one or less, and exhibit high thermal and photostability (1, 3). The physiological function of WSCPs is still not known. Although WSCPs have a sequence similarity of ϳ30% with Künitz-type proteinase inhibitors, no significant protease inhibitor activity of WSCPs has yet been identified (4 -6). The low Chl content per protein makes it unlikely that WSCPs are involved in the light reaction of photosynthesis. Meanwhile, it has been speculated (7, 8) that WSCP acts as a scavenger of free Chl, by transporting it from the thylakoid membrane to the chloroplast envelope, where Chlase, the enzyme that initiates the Chl catabolism, is thought to reside (9).An in vitro binding assay with the recombinant apo-WSCP cloned from cauliflower (Brassica oleralcea var. Botrys) and Chl or its derivatives showed that the central Mg 2ϩ ion and the phytyl tail of Chl were essential for protein-pigment binding and tetrameric assembly, respectively (1). Furthermore, the recombinant apo-WSCP was able to remove Chl from the thylakoid membrane in vitro and organize the tetrameric WSCPChl complex (3). The absorption spectrum of the reconstituted complex is very similar to that of the native WSCP-Chl complex purified from fresh leaves (1, 3).The WSCP-Chl complex retains its fresh green color under dim light for months, enough for a long term crystallization experiment. Free Chl, on t...

show abstract

“…1). Further downstream, the porphyrin breakdown products are modified and exported to the vacuole, where they are stored indefinitely (Hö rtensteiner, 1999(Hö rtensteiner, , 2004Matile et al, 1999;Takamiya et al, 2000). Beyond the established enzymatic chlorophyll breakdown pathway, recent data from stay-green mutants suggests the involvement of an additional player in chlorophyll degradation: the SGR gene product, which likely functions upstream of the catabolic enzymes (Aubry et al, 2008) and has been suggested to function as a destabilizer of the light-harvesting complex (LHC; Park et al, 2007;Fig.…”

mentioning

confidence: 99%

Citrus Chlorophyllase Dynamics at Ethylene-Induced Fruit Color-Break: A Study of Chlorophyllase Expression, Posttranslational Processing Kinetics, and in Situ Intracellular Localization

et al. 2008

View full text Add to dashboard Cite

Fruit color-break is the visual manifestation of the developmentally regulated transition of chloroplasts to chromoplasts during fruit ripening and often involves biosynthesis of copious amounts of carotenoids concomitant with massive breakdown of chlorophyll. Regulation of chlorophyll breakdown at different physiological and developmental stages of the plant life cycle, particularly at fruit color-break, is still not well understood. Here, we present the dynamics of native chlorophyllase (Chlase) and chlorophyll breakdown in lemon (Citrus limon) fruit during ethylene-induced color-break. We show, using in situ immunofluorescence on ethylene-treated fruit peel (flavedo) tissue, that citrus Chlase is located in the plastid, in contrast to recent reports suggesting cytoplasmic localization of Arabidopsis (Arabidopsis thaliana) Chlases. At the intra-organellar level, Chlase signal was found to overlap mostly with chlorophyll fluorescence, suggesting association of most of the Chlase protein with the photosynthetic membranes. Confocal microscopy analysis showed that the kinetics of chlorophyll breakdown was not uniform in the flavedo cells. Chlorophyll quantity at the cellular level was negatively correlated with plastid Chlase accumulation; plastids with reduced chlorophyll content were found by in situ immunofluorescence to contain significant levels of Chlase, while plastids containing still-intact chlorophyll lacked any Chlase signal. Immunoblot and protein-mass spectrometry analyses were used to demonstrate that citrus Chlase initially accumulates as an approximately 35-kD precursor, which is subsequently N-terminally processed to approximately 33-kD mature forms by cleavage at either of three consecutive amino acid positions. Chlase plastid localization, expression kinetics, and the negative correlation with chlorophyll levels support the central role of the enzyme in chlorophyll breakdown during citrus fruit color-break.

show abstract

Chlorophyll breakdown in higher plants and algae

Cited by 136 publications

References 164 publications

TheArabidopsis vitamin E pathway gene5-1Mutant Reveals a Critical Role for Phytol Kinase in Seed Tocopherol Biosynthesis

TheArabidopsis vitamin E pathway gene5-1Mutant Reveals a Critical Role for Phytol Kinase in Seed Tocopherol Biosynthesis

Structural Mechanism and Photoprotective Function of Water-soluble Chlorophyll-binding Protein

Citrus Chlorophyllase Dynamics at Ethylene-Induced Fruit Color-Break: A Study of Chlorophyllase Expression, Posttranslational Processing Kinetics, and in Situ Intracellular Localization

Contact Info

Product

Resources

About