chlorophyll breakdown; leaf senescence; fruit ripening; evolution; protein-protein interaction; phytol hydrolysis; protein crystallization
Süssenbacher Iris, Christ Bastien, Hörtensteiner Stefan, Kräutler Bernhard (2014), Hydroxymethylated phyllobilins: a puzzling new feature of the dioxobilin branch of chlorophyll breakdown., in Chemistry Eur. J.
, 20(1), 87-92.
Christ Bastien, Hörtensteiner Stefan (2014), Mechanism and significance of chlorophyll breakdown, in Journal of Plant Growth Regulation
, 33, 4-20.
Sakuraba Yasuhito, Kim Ye-Sol, Yoo Soo-Cheul, Hörtensteiner Stefan, Paek Nam-Chon (2013), 7-Hydroxymethyl chlorophyll a reductase functions in metabolic channeling of chlorophyll breakdown intermediates during leaf senescence., in Biochemical and Biophysical Research Communications
, 430, 32-37.
Kräutler Bernhard, Hörtensteiner Stefan (2013), Chlorophyll breakdown: chemistry, biochemistry and biology, in Ferreira G.C. (ed.), World Scientific Publishing, Hackensack, NJ, USA, 117-185.
Christ Bastien, Süssenbacher Iris, Moser Simone, Bichsel Nicole, Egert Aurelie, Müller Thomas, Kräutler Bernhard, Hörtensteiner Stefan (2013), Cytochrome P450 CYP89A9 is involved in the formation of major chlorophyll catabolites during leaf senescence in Arabidopsis., in The Plant Cell
, 25(5), 1868-80.
Hörtensteiner Stefan (2013), Update on the biochemistry of chlorophyll breakdown., in Plant Molecular Biology
, 82, 505-517.
Pattanayak Gopal K, Venkataramani Sujatha, Hörtensteiner Stefan, Kunz Lukas, Christ Bastien, Moulin Michael, Smith Alison G, Okamoto Yukihiro, Tamiaki Hitoshi, Sugishima Masakazu, Greenberg Jean T (2012), Accelerated cell death 2 suppresses mitochondrial oxidative bursts and modulates cell death in Arabidopsis., in The Plant Journal
, 69(4), 589-600.
Grassl Julia, Pružinská Adriana, Hörtensteiner Stefan, Taylor Nicolas L, Millar A Harvey (2012), Early events in plastid protein degradation in stay-green Arabidopsis reveal differential regulation beyond the retention of LHCII and chlorophyll., in Journal of Proteome Research
, 11(11), 5443-52.
Christ Bastien, Schelbert Silvia, Aubry Sylvain, Süssenbacher Iris, Müller Thomas, Kräutler Bernhard, Hörtensteiner Stefan (2012), MES16, a member of the methylesterase protein family, specifically demethylates fluorescent chlorophyll catabolites during chlorophyll breakdown in Arabidopsis., in Plant Physiology
, 158(2), 628-41.
Sakuraba Yasuhito, Schelbert Silvia, Park So-Yon, Han Su-Hyun, Lee Byoung-Doo, Andrès Céline Besagni, Kessler Felix, Hörtensteiner Stefan, Paek Nam-Chon (2012), STAY-GREEN and chlorophyll catabolic enzymes interact at light-harvesting complex II for chlorophyll detoxification during leaf senescence in Arabidopsis., in The Plant Cell
, 24(2), 507-18.
Hörtensteiner Stefan, Kräutler Bernhard (2011), Chlorophyll breakdown in higher plants., in Biochimica et Biophysica Acta
, 1807(8), 977-88.
Sakuraba Yasuhito, Park So-Yon, Kim Ye-Sol, Wang Seung-Hyun, Yoo Soo-Cheul, Hörtensteiner Stefan, Paek Nam-Chon, Arabidopsis STAY-GREEN2 Is a Negative Regulator of Chlorophyll Degradation during Leaf Senescence., in Molecular Plant
Sakuraba Yasuhito, Lee Sang-Hwa, Kim Ye-Sol, Park Ohkmae K, Hörtensteiner Stefan, Paek Nam-Chon, Delayed degradation of chlorophylls and photosynthetic proteins in Arabidopsis autophagy mutants during stress-induced leaf yellowing., in Journal of Experimental Botany
Christ Bastien, Egert Aurélie, Süssenbacher Iris, Kräutler Bernhard, Bartels Dorothea, Peters Shaun, Hörtensteiner Stefan, Water deficit induces chlorophyll degradation via the 'PAO/phyllobilin' pathway in leaves of homoio- (Craterostigma pumilum) and poikilochlorophyllous (Xerophyta viscosa) resurrection plants., in Plant, Cell & Environment
Title: Chlorophyll breakdown: analysis of fruit ripening, evolution and regulation.Project summary1. Background. Loss of green color during leaf senescence and fruit ripening is the result of chlorophyll degradation to colorless catabolites. Whereas most of the enzymes and intermediates of leaf senescence-related chlorophyll breakdown are known, fruit ripening has only partially been analyzed in this respect. In particular, inconsistent data exist about the enzyme(s) being responsible for phytol removal, an early reaction in the pathway. Pheophytinase was shown to be involved during leaf senescence and to catalyze dephytylation of pheophytin (Mg-free chlorophyll), in contrast to chlorophyllase, which acts on chlorophyll. It is unclear whether pheophytinase is involved in fruit ripening. In addition, the specificity of pheophytinase is intriguing and calls for further biochemical analysis. Most of the reactions of chlorophyll breakdown occur in the chloroplast and recent, preliminary, results in our lab indicate that different enzymes form a protein complex, yet this remains to be verified. In recent years, several chlorophyll catabolic genes mainly from Arabidopsis thaliana and rice were cloned. Homologous sequences are also present in lower plants, including eu- and prokaryotic photosynthetic organisms, but none of these proteins has functionally been characterized yet. 2. Working hypothesis. Although the pathway of chlorophyll breakdown during leaf senescence in higher plants is rather well understood, questions remain concerning the pathway in fruit ripening, its presence in lower plants and the mode of pathway regulation. The following questions can be raised:- Is the pathway of chlorophyll breakdown during fruit ripening identical to the one in leaf senescence?- What are the biochemical properties of pheophytinase?- Do chlorophyll catabolic enzymes inside the chloroplast form a multiprotein complex?- To what extend is the pathway of chlorophyll breakdown evolutionary conserved?- What are the regulatory mechanisms of chlorophyll breakdown?3. Specific aims. To address some of these chlorophyll breakdown-related questions, we have the following aims:- establishing tomato as a model for both leaf senescence and fruit ripening, with a particular focus on pheophytinase- analyzing biochemical properties of pheophytinase, including crystal structure analysis of the protein - analyzing interaction of different chl catabolic proteins- analyzing evolutionary aspects by characterizing potential catabolic enzymes from lower plants and algae- identifying regulatory factors by isolating suppressors of pao1, a catabolic mutant exhibiting a cell death phenotype4. Methods. Carrying out the proposed research involves a variety of molecular, biochemical and analytical methods, such as (i) production of transgenic plants, (ii) mutant identification, crossing and analysis, (iii) expression and enzymatic analysis of enzymes, (iv) chromatographic methods, (v) pigment and protein structure analysis techniques, and (vi) confocal microscopy.5. Expected value of the proposed project. The research proposed here will allow new insight into different aspects of chl breakdown, which are so far unexplored. It will answer questions about the evolution of chlorophyll breakdown and will allow elucidating the pathway in ripening fruit. This together with the elucidation of regulatory factors might provide interesting targets for modulating fruit ripening for economic purposes.