교육과학기술부 글로벌프론티어 (재)멀티스케일 에너지 시스템 연구단은 나노기술과 에너지 기술의 융합을 통하여 혁신적 미래 광에너지와 분자에너지 원천기술 개발을 목표로 하는 멀티스케일 에너지 시스템 연구사업을 추진하고 있습니다. 연구단에서는 격주로 멀티스케일 에너지 강좌를 개최합니다.
관심 있는 분들의 많은 참석 바랍니다.
1. 제 목 : Energy Balances in Plants and Algae
2. 연 사 : 안태규 교수 (성균관대 에너지과학과)
3. 일 시 : 2012년 6월 4일 (월) 16:00 ~ 17:00
4. 장 소 : 서울대학교 신공학관 (301동) 117호 세미나실
5. 내 용 :
Abstract :
In plants, antenna supercomplexes (SCs) play two opposing roles; efficiently transfering absorbed energy to reaction center (photosynthesis) and harmlessly dissipating excessively absorbed light energy as heat (photoprotection).1 The former is to generate sugars and chemical energies for plant survival, instead the latter aims to avoid inevitably generated deleterious oxygen-related byproducts (i.e. reactive oxygen species). The radiation-less relaxation is called non-photochemical quenching (NPQ) and is critical for plant survival and fitness.2 NPQ is predominantly mediated by a rapid response to photon flux density, or energy-dependent quenching (qE).3, 4 qE can regulate reversibly photosynthesis depending on low lumen pH,5 de-epoxidized xanthophylls, e.g. zeaxanthin (Z),6 and the antenna-associated membrane protein PsbS7. All these components of qE are linearly correlated to charge transfer (CT) quenching involving an electron transfer from Z to chlorophyll(s) (Chls) in thylakoid membranes of C-3 plant Arabidopsis thaliana.8-10
Antenna SCs in photosystem II (PSII) are composed of LHCII trimers, major peripheral antenna light-harvesting complexes (LHCs), and minor chlorophyll protein complexes (mCPs, i.e. CP24, CP26, and CP29). All the LHCs contain chlorophylls (Chls) a and b, and carotenoids (Cars), i.e. lutein (L), violaxanthin (V), and neoxanthin (N). In light-adapted plants, specifically V can be converted into Z by an enzyme i.e. violaxanthin de-epoxidase which is activated under low pH. To pinpoint where CT quenching occurs in antenna SCs, we explored antenna LHCs systematically from LHCII trimer to individual LHC monomers; each comparing with Z-bound and V-bound LHCs which are analogs to light-adapted and dark-adapted conditions, respectively. Recently we found CT quenching in all isolated mCPs (CP24, CP26, and CP29),9, 11, 12 while we could not observe any trace of Z•+ in LHCII trimer.9 Furthermore, especially in CP29 we revealed molecular architecture of CT quenching including a Chl dimer (Chls A5 and B5) and Z.11 mCPs are proximately located in the middle between LHCII antenna and D1/D2 core complexes where the reaction centers (RCs) are located, a perfect geometry to regulate the downstream energy flow from antenna LHCs to RCs.
1. Blankenship, R. E., Molecular mechanisms of photosynthesis. Blackwell Science: Oxford ; Malden, MA, 2002.
2. Kulheim, C.; Agren, J.; Jansson, S., Science 2002, 297, (5578), 91-93.
3. Horton, P.; Ruban, A. V.; Walters, R. G., Annual Review of Plant Physiology and Plant Molecular Biology 1996, 47, 655-684.
4. Niyogi, K. K., Annual Review of Plant Physiology and Plant Molecular Biology 1999, 50, 333-359.
5. Briantais, J. M.; Vernotte, C.; Picaud, M.; Krause, G. H., Biochim Biophys Acta 1979, 548, (1), 128-38.
6. Demmig-Adams, B., Biochim Biophys Acta 1990, 1020, 1.
7. Liu, Z. F.; Yan, H. C.; Wang, K. B.; Kuang, T. Y.; Zhang, J. P.; Gui, L. L.; An, X. M.; Chang, W. R., Nature 2004, 428, (6980), 287-292.
8. Ahn, T. K.; Avenson, T. J.; Peers, G.; Li, Z.; Dall'Osto, L.; Bassi, R.; Niyogi, K. K.; Fleming, G. R., Chemical Physics 2009.
9. Avenson, T. J.; Ahn, T. K.; Zigmantas, D.; Niyogi, K. K.; Li, Z.; Ballottari, M.; Bassi, R.; Fleming, G. R., Journal of Biological Chemistry 2008, 283, (6), 3550-3558.
10. Holt, N. E.; Zigmantas, D.; Valkunas, L.; Li, X. P.; Niyogi, K. K.; Fleming, G. R., Science 2005, 307, (5708), 433-436.
11. Ahn, T. K.; Avenson, T. J.; Ballottari, M.; Cheng, Y. C.; Niyogi, K. K.; Bassi, R.; Fleming, G. R., Science 2008, 320, (5877), 794-797.
12. Avenson, T. J.; Ahn, T. K.; Niyogi, K. K.; Ballottari, M.; Bassi, R.; Fleming, G. R., Journal of Biological Chemistry 2009.
6. 약 력 :
Tae Kyu Ahn received his Ph. D. at Seoul National University in 2005. He experienced his postdoctoral work at Yonsei University in 2005 and at Lawrence Berkeley National Laboratory from 2006 to 2009. Since 2009.8, he is an assistant professor in Department of Energy Science at Sungkyunkwan university. His main research interests include (a) ultrafast dynamics of plant photosynthesis, (b) transient spectroscopy of in vitro membrane proteins, (c) in vivo spectroscopic imaging of living cells, (d) antioxidants in plant cells.
문 의 : 멀티스케일 에너지 시스템 연구단 연구지원본부 (☏ 880-6669,6670)
남기태 교수 (재료공학부), 최만수 교수 (기계항공공학부)
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