Regulation of iron-homeostasis in the chloroplast of Chlamydomonas reinhardtii: Dynamic remodeling of the photosynthetic machinery in response to iron availability
Zusammenfassung der Projektergebnisse
In the framework of the granted work, we took advantage of quantitative mass spectrometry to characterize the acclimation of Chlamydomonas reinhardtii to iron deficiency. These analyses provided new insights into coordinated remodeling of bioenergetics pathways and iron deficiency responses in C. reinhardtii and revealed interdependencies with the cellular metabolic status. An important conclusion from the work is that remodeling of bioenergetics pathways under iron-deficiency is modulated by the cellular metabolic status. In particular, analyses of ferritin knockdown and adh1 knockout mutants suggested that the low iron regulatory acclimation networks are particularly sensitive to the chloroplast metabolic and/or redox status. Furthermore the proteomic work identified candidate genes such as LHCSR3, PGRL1 and CAS that play important roles in minimizing photooxidative stress during remodeling of the photosynthetic apparatus. The molecular analyses of CAS, LHCSR3 and PGRL1 revealed functions which fundamentally exceed their requirements for acclimation to iron deficiency. LHCSR3 is necessary for qE in Chlamydomonas. Efficient qE, on the other hand, needs functional photosynthetic electron transfer for sufficient acidification of the thylakoid lumen. Hereby cyclic photosynthetic electron flow (CEF) is important and, both, PGRL1 and CAS are essential for efficient CEF. In parallel presence of CAS is also needed for successful expression of LHCSR3. In summary, efficient CEF and increase in LHCSR3 expression are required for acclimation to iron deficiency. Thus our work discovered an interconnected network of proteins that are key actors in qE and CEF and are generally involved in acclimation to adverse environmental conditions and in particular in acclimation to iron deficiency.
Projektbezogene Publikationen (Auswahl)
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(2007) Comparative quantitative proteomics to investigate the remodeling of bioenergetic pathways under iron deficiency in Chlamydomonas reinhardtii. Proteomics 7: 3964-3979
Naumann B, Busch A, Allmer J, Ostendorf E, Zeller M, Kirchhoff H, Hippler M
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(2008) Ferritin is required for rapid remodeling of the photosynthetic apparatus and minimizes photo-oxidative stress in response to iron availability in Chlamydomonas reinhardtii. Plant J 55: 201-211
Busch A, Rimbauld B, Naumann B, Rensch S, Hippler M
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(2009) An ancient light-harvesting protein is critical for the regulation of algal photosynthesis. Nature 462: 518-521
Peers G, Truong TB, Ostendorf E, Busch A, Elrad D, Grossman AR, Hippler M, Niyogi KK
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(2009) Chlamydomonas proteomics. Curr Opin Microbiol 12: 285-291
Rolland N, Atteia A, Decottignies P, Garin J, Hippler M, Kreimer G, Lemaire SD, Mittag M, Wagner V
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(2009) PGRL1 participates in iron-induced remodeling of the photosynthetic apparatus and in energy metabolism in Chlamydomonas reinhardtii. J Biol Chem 284: 32770-32781
Petroutsos D, Terauchi AM, Busch A, Hirschmann I, Merchant SS, Finazzi G, Hippler M
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(2009) Proteomics of metal mediated protein dynamics in plants - iron and cadmium in the focus. Frontiers in Biosciences 14: 1955-1969
Clemens S, Naumann B, Hippler M
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(2011) Control of Hydrogen Photoproduction by the Proton Gradient Generated by Cyclic Electron Flow in Chlamydomonas reinhardtii. The Plant cell 23: 2619-2630
Tolleter D, Ghysels B, Alric J, Petroutsos D, Tolstygina I, Krawietz D, Happe T, Auroy P, Adriano JM, Beyly A, Cuine S, Plet J, Reiter IM, Genty B, Cournac L, Hippler M, Peltier G
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(2011) The Chloroplast Calcium Sensor CAS Is Required for Photoacclimation in Chlamydomonas reinhardtii. The Plant cell 23: 2950-2963
Petroutsos D, Busch A, Janssen I, Trompelt K, Bergner SV, Weinl S, Holtkamp M, Karst U, Kudla J, Hippler M
