1
|
Wang G, Mao J, Ji M, Wang W, Fu J. A comprehensive assessment of photosynthetic acclimation to shade in C4 grass (Cynodon dactylon (L.) Pers.). BMC PLANT BIOLOGY 2024; 24:591. [PMID: 38902617 PMCID: PMC11191358 DOI: 10.1186/s12870-024-05242-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 06/03/2024] [Indexed: 06/22/2024]
Abstract
BACKGROUND Light deficit in shaded environment critically impacts the growth and development of turf plants. Despite this fact, past research has predominantly concentrated on shade avoidance rather than shade tolerance. To address this, our study examined the photosynthetic adjustments of Bermudagrass when exposed to varying intensities of shade to gain an integrative understanding of the shade response of C4 turfgrass. RESULTS We observed alterations in photosynthetic pigment-proteins, electron transport and its associated carbon and nitrogen assimilation, along with ROS-scavenging enzyme activity in shaded conditions. Mild shade enriched Chl b and LHC transcripts, while severe shade promoted Chl a, carotenoids and photosynthetic electron transfer beyond QA- (ET0/RC, φE0, Ψ0). The study also highlighted differential effects of shade on leaf and root components. For example, Soluble sugar content varied between leaves and roots as shade diminished SPS, SUT1 but upregulated BAM. Furthermore, we observed that shading decreased the transcriptional level of genes involving in nitrogen assimilation (e.g. NR) and SOD, POD, CAT enzyme activities in leaves, even though it increased in roots. CONCLUSIONS As shade intensity increased, considerable changes were noted in light energy conversion and photosynthetic metabolism processes along the electron transport chain axis. Our study thus provides valuable theoretical groundwork for understanding how C4 grass acclimates to shade tolerance.
Collapse
Affiliation(s)
- Guangyang Wang
- Coastal Salinity Tolerant Grass Engineering and Technology Research Center, Ludong University, Yantai, 264025, Shandong, China
| | - Jinyan Mao
- College of Agriculture, Ludong University, Yantai, 264025, Shandong, China
| | - Mingxia Ji
- Coastal Salinity Tolerant Grass Engineering and Technology Research Center, Ludong University, Yantai, 264025, Shandong, China
| | - Wei Wang
- Coastal Salinity Tolerant Grass Engineering and Technology Research Center, Ludong University, Yantai, 264025, Shandong, China
| | - Jinmin Fu
- Coastal Salinity Tolerant Grass Engineering and Technology Research Center, Ludong University, Yantai, 264025, Shandong, China.
| |
Collapse
|
2
|
Arvaniti E, Levizou E, Kyparissis A. Near-Zero Temperatures Arrest Movement of the Diaheliotropic Malva sylvestris. PLANTS (BASEL, SWITZERLAND) 2023; 12:2484. [PMID: 37447045 DOI: 10.3390/plants12132484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/08/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023]
Abstract
In the present study, the diaheliotropic leaf movement pattern of Malva sylvestris in relation to the impact of low temperature is presented. Seasonal measurements of movement characteristics along with important aspects of plant function, such as chlorophyll content, water potential, PSII photochemistry, and phenological parameters were performed on plants in their natural environment. During the study period, low winter temperatures and a 10-day freezing event gave insights into the plant's response to harsh environmental conditions and the effect of the latter on leaf movement profile. Plant growth was significantly inhibited during low-temperature periods (leaf shedding) and the photosynthetic performance was seriously depressed, as judged by in vivo chlorophyll a fluorescence. Additionally, the diaheliotropic leaf movement pattern was arrested. Temperature rise in March triggered new leaf burst and expansion, enhancement of the photosynthetic performance, and the recovery of the diaheliotropic movement. The daily and seasonal profiles of the water potential were synergistically shaped by leaf movement and climatic conditions. We conclude that diaheliotropism of M. sylvestris is a dynamic process that coordinates with the prevailing temperatures in ecosystems like the studied one, reaching a full arrest under near-zero temperatures to protect the photosynthetic apparatus from over-excitation and prevent photoinhibition.
Collapse
Affiliation(s)
- Elena Arvaniti
- Department of Biological Applications and Technology, University of Ioannina, 451 10 Ioannina, Greece
| | - Efi Levizou
- Department of Agricultural Crop Production and Rural Environment, University of Thessaly, Fytokou Str., 384 46 Volos, Greece
| | - Aris Kyparissis
- Department of Agricultural Crop Production and Rural Environment, University of Thessaly, Fytokou Str., 384 46 Volos, Greece
| |
Collapse
|
3
|
Espinoza‐Corral R, Schwenkert S, Schneider A. Characterization of the preferred cation cofactors of chloroplast protein kinases in Arabidopsis thaliana. FEBS Open Bio 2023; 13:511-518. [PMID: 36683405 PMCID: PMC9989932 DOI: 10.1002/2211-5463.13563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/09/2023] [Accepted: 01/20/2023] [Indexed: 01/24/2023] Open
Abstract
Chloroplasts sense a variety of stimuli triggering several acclimation responses. One prominent response is the mechanism of state transitions, which enables rapid adaption to changes in illumination. Here, we investigated the link between divalent cations (calcium, magnesium, and manganese) and protein kinase activity in Arabidopsis chloroplasts. Our results show that manganese ions are the strongest activator of kinase activity in chloroplasts followed by magnesium ions, whereas calcium ions are not able to induce kinase activity. Additionally, the phosphorylation of specific protein bands is strongly reduced in chloroplasts of a cmt1 mutant, which is impaired in manganese import into chloroplasts, as compared to the wild-type. These findings provide insights for the future characterization of chloroplast protein kinase activity and potential target proteins.
Collapse
Affiliation(s)
| | - Serena Schwenkert
- Plant Molecular Biology, Faculty of BiologyLudwig Maximilians University MunichPlaneggGermany
| | - Anja Schneider
- Plant Molecular Biology, Faculty of BiologyLudwig Maximilians University MunichPlaneggGermany
| |
Collapse
|
4
|
Navakoudis E, Kotzabasis K. Polyamines: Α bioenergetic smart switch for plant protection and development. JOURNAL OF PLANT PHYSIOLOGY 2022; 270:153618. [PMID: 35051689 DOI: 10.1016/j.jplph.2022.153618] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/09/2022] [Accepted: 01/10/2022] [Indexed: 05/27/2023]
Abstract
The present review highlights the bioenergetic role of polyamines in plant protection and development and proposes a universal model for describing polyamine-mediated stress responses. Any stress condition induces an excitation pressure on photosystem II by reforming the photosynthetic apparatus. To control this phenomenon, polyamines act directly on the molecular structure and function of the photosynthetic apparatus as well as on the components of the chemiosmotic proton-motive force (ΔpH/Δψ), thus regulating photochemical (qP) and non-photochemical quenching (NPQ) of energy. The review presents the mechanistic characteristics that underline the key role of polyamines in the structure, function, and bioenergetics of the photosynthetic apparatus upon light adaptation and/or under stress conditions. By following this mechanism, it is feasible to make stress-sensitive plants to be tolerant by simply altering their polyamine composition (especially the ratio of putrescine to spermine), either chemically or by light regulation.
Collapse
Affiliation(s)
- Eleni Navakoudis
- Department of Biology, University of Crete, Voutes University Campus, 70013, Heraklion, Greece; Department of Chemical Engineering, Cyprus University of Technology, 3603, Limassol, Cyprus
| | - Kiriakos Kotzabasis
- Department of Biology, University of Crete, Voutes University Campus, 70013, Heraklion, Greece.
| |
Collapse
|
5
|
Yang YJ, Zhang SB, Wang JH, Huang W. The decline in photosynthetic rate upon transfer from high to low light is linked to the slow kinetics of chloroplast ATP synthase in Bletilla striata. PHOTOSYNTHESIS RESEARCH 2020; 144:13-21. [PMID: 32166520 DOI: 10.1007/s11120-020-00725-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 02/12/2020] [Indexed: 06/10/2023]
Abstract
Upon a sudden transition from high to low light, the rate of CO2 assimilation (AN) in some plants first decreases to a low level before gradually becoming stable. However, the underlying mechanisms remain controversial. The activity of chloroplast ATP synthase (gH+) is usually depressed under high light when compared with low light. Therefore, we hypothesize that upon a sudden transfer from high to low light, the relatively low gH+ restricts ATP synthesis and thus causes a reduction in AN. To test this hypothesis, we measured gas exchange, chlorophyll fluorescence, P700 redox state, and electrochromic shift signals in Bletilla striata (Orchidaceae). After the transition from saturating to lower irradiance, AN and ETRII decreased first to a low level and then gradually increased to a stable value. Within the first seconds after transfer from high to low light, gH+ was maintained at low levels. During further exposure to low light, gH+ gradually increased to a stable value. Interestingly, a tight positive relationship was found between gH+ and ETRII. These results suggested that upon a sudden transition from high to low light, AN was restricted by gH+ at the step of ATP synthesis. Taken together, we propose that the decline in AN upon sudden transfer from high to low light is linked to the slow kinetics of chloroplast ATP synthase.
Collapse
Affiliation(s)
- Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Ji-Hua Wang
- Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China.
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
| |
Collapse
|
6
|
Van Wittenberghe S, Alonso L, Malenovský Z, Moreno J. In vivo photoprotection mechanisms observed from leaf spectral absorbance changes showing VIS-NIR slow-induced conformational pigment bed changes. PHOTOSYNTHESIS RESEARCH 2019; 142:283-305. [PMID: 31541418 PMCID: PMC6874624 DOI: 10.1007/s11120-019-00664-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 08/13/2019] [Indexed: 05/29/2023]
Abstract
Regulated heat dissipation under excessive light comprises a complexity of mechanisms, whereby the supramolecular light-harvesting pigment-protein complex (LHC) shifts state from light harvesting towards heat dissipation, quenching the excess of photo-induced excitation energy in a non-photochemical way. Based on whole-leaf spectroscopy measuring upward and downward spectral radiance fluxes, we studied spectrally contiguous (hyperspectral) transient time series of absorbance A(λ,t) and passively induced chlorophyll fluorescence F(λ,t) dynamics of intact leaves in the visible and near-infrared wavelengths (VIS-NIR, 400-800 nm) after sudden strong natural-like illumination exposure. Besides light avoidance mechanism, we observed on absorbance signatures, calculated from simultaneous reflectance R(λ,t) and transmittance T(λ,t) measurements as A(λ,t) = 1 - R(λ,t) - T(λ,t), major dynamic events with specific onsets and kinetical behaviour. A consistent well-known fast carotenoid absorbance feature (500-570 nm) appears within the first seconds to minutes, seen from both the reflected (backscattered) and transmitted (forward scattered) radiance differences. Simultaneous fast Chl features are observed, either as an increased or decreased scattering behaviour during quick light adjustment consistent with re-organizations of the membrane. The carotenoid absorbance feature shows up simultaneously with a major F decrease and corresponds to the xanthophyll conversion, as quick response to the proton gradient build-up. After xanthophyll conversion (t = 3 min), a kinetically slower but major and smooth absorbance increase was occasionally observed from the transmitted radiance measurements as wide peaks in the green (~ 550 nm) and the near-infrared (~ 750 nm) wavelengths, involving no further F quenching. Surprisingly, in relation to the response to high light, this broad and consistent VIS-NIR feature indicates a slowly induced absorbance increase with a sigmoid kinetical behaviour. In analogy to sub-leaf-level observations, we suggest that this mechanism can be explained by a structure-induced low-energy-shifted energy redistribution involving both Car and Chl. These findings might pave the way towards a further non-invasive spectral investigation of antenna conformations and their relations with energy quenching at the intact leaf level, which is, in combination with F measurements, of a high importance for assessing plant photosynthesis in vivo and in addition from remote observations.
Collapse
Affiliation(s)
- Shari Van Wittenberghe
- Laboratory of Earth Observation, Image Processing Laboratory, University of Valencia, C/Catedrático José Beltrán, 2, 46980 Paterna, Valencia Spain
- Optics of Photosynthesis Laboratory, Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, 00014 Helsinki, Finland
| | - Luis Alonso
- Laboratory of Earth Observation, Image Processing Laboratory, University of Valencia, C/Catedrático José Beltrán, 2, 46980 Paterna, Valencia Spain
| | - Zbyněk Malenovský
- Geography and Spatial Sciences, School of Technology, Environments and Design, University of Tasmania, Private Bag 76, Hobart, TAS 7001 Australia
| | - José Moreno
- Laboratory of Earth Observation, Image Processing Laboratory, University of Valencia, C/Catedrático José Beltrán, 2, 46980 Paterna, Valencia Spain
| |
Collapse
|
7
|
Furukawa R, Aso M, Fujita T, Akimoto S, Tanaka R, Tanaka A, Yokono M, Takabayashi A. Formation of a PSI-PSII megacomplex containing LHCSR and PsbS in the moss Physcomitrella patens. JOURNAL OF PLANT RESEARCH 2019; 132:867-880. [PMID: 31541373 DOI: 10.1007/s10265-019-01138-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 09/08/2019] [Indexed: 05/10/2023]
Abstract
Mosses are one of the earliest land plants that diverged from fresh-water green algae. They are considered to have acquired a higher capacity for thermal energy dissipation to cope with dynamically changing solar irradiance by utilizing both the "algal-type" light-harvesting complex stress-related (LHCSR)-dependent and the "plant-type" PsbS-dependent mechanisms. It is hypothesized that the formation of photosystem (PS) I and II megacomplex is another mechanism to protect photosynthetic machinery from strong irradiance. Herein, we describe the analysis of the PSI-PSII megacomplex from the model moss, Physcomitrella patens, which was resolved using large-pore clear-native polyacrylamide gel electrophoresis (lpCN-PAGE). The similarity in the migration distance of the Physcomitrella PSI-PSII megacomplex to the Arabidopsis megacomplex shown during lpCN-PAGE suggested that the Physcomitrella PSI-PSII and Arabidopsis megacomplexes have similar structures. Time-resolved chlorophyll fluorescence measurements show that excitation energy was rapidly and efficiently transferred from PSII to PSI, providing evidence of an ordered association of the two photosystems. We also found that LHCSR and PsbS co-migrated with the Physcomitrella PSI-PSII megacomplex. The megacomplex showed pH-dependent chlorophyll fluorescence quenching, which may have been induced by LHCSR and/or PsbS proteins with the collaboration of zeaxanthin. We discuss the mechanism that regulates the energy distribution balance between two photosystems in Physcomitrella.
Collapse
Affiliation(s)
- Ryo Furukawa
- Institute of Low-Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819, Japan
| | - Michiki Aso
- Institute of Low-Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819, Japan
| | - Tomomichi Fujita
- Faculty of Science, Hokkaido University, N10 W8 Kita-ku, Sapporo, 060-0810, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
| | - Ryouichi Tanaka
- Institute of Low-Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819, Japan
| | - Ayumi Tanaka
- Institute of Low-Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819, Japan
| | - Makio Yokono
- Institute of Low-Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819, Japan.
- Innovation Center, Nippon Flour Mills Co., Ltd., Atsugi, 243-0041, Japan.
| | - Atsushi Takabayashi
- Institute of Low-Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819, Japan
| |
Collapse
|
8
|
Night Light-Adaptation Strategies for Photosynthetic Apparatus in Yellow-Poplar (Liriodendron tulipifera L.) Exposed to Artificial Night Lighting. FORESTS 2018. [DOI: 10.3390/f9020074] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
9
|
Tadepalli S, Slocik JM, Gupta MK, Naik RR, Singamaneni S. Bio-Optics and Bio-Inspired Optical Materials. Chem Rev 2017; 117:12705-12763. [PMID: 28937748 DOI: 10.1021/acs.chemrev.7b00153] [Citation(s) in RCA: 174] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Through the use of the limited materials palette, optimally designed micro- and nanostructures, and tightly regulated processes, nature demonstrates exquisite control of light-matter interactions at various length scales. In fact, control of light-matter interactions is an important element in the evolutionary arms race and has led to highly engineered optical materials and systems. In this review, we present a detailed summary of various optical effects found in nature with a particular emphasis on the materials and optical design aspects responsible for their optical functionality. Using several representative examples, we discuss various optical phenomena, including absorption and transparency, diffraction, interference, reflection and antireflection, scattering, light harvesting, wave guiding and lensing, camouflage, and bioluminescence, that are responsible for the unique optical properties of materials and structures found in nature and biology. Great strides in understanding the design principles adapted by nature have led to a tremendous progress in realizing biomimetic and bioinspired optical materials and photonic devices. We discuss the various micro- and nanofabrication techniques that have been employed for realizing advanced biomimetic optical structures.
Collapse
Affiliation(s)
- Sirimuvva Tadepalli
- Department of Mechanical Engineering and Materials Science and Institute of Materials Science and Engineering, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | | | | | | | - Srikanth Singamaneni
- Department of Mechanical Engineering and Materials Science and Institute of Materials Science and Engineering, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| |
Collapse
|
10
|
Fujisawa T, Leverenz RL, Nagamine M, Kerfeld CA, Unno M. Raman Optical Activity Reveals Carotenoid Photoactivation Events in the Orange Carotenoid Protein in Solution. J Am Chem Soc 2017; 139:10456-10460. [PMID: 28692285 DOI: 10.1021/jacs.7b05193] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The orange carotenoid protein (OCP) plays an important role in photoprotection in cyanobacteria, which is achieved by the photoconversion from the orange dark state (OCPO) to the red active state (OCPR). Using Raman optical activity (ROA), we studied the conformations of the carotenoid chromophore in the active sites of OCPO and OCPR. This ROA measurement directly observed the chromophore conformation of native OCP in solution, and the measurement of OCPR first demonstrated the ROA spectroscopy for the transient species. For OCPO, the spectral features of ROA were mostly reproduced by the quantum chemical calculation based on the crystal structure of the OCP. Within the spatial resolution (∼2 Å), a slight modification of the polyene-chain distortion improved the agreement between the observed and calculated ROA spectra. While the crystal structure of OCPR is not available, the ROA spectrum of OCPR was reproduced by using the crystal structure of red carotenoid protein (RCP), an OCPR proxy. The present results showed that the chromophore conformations in the crystal structures of OCP and RCP hold true for OCPO and OCPR in solution. Particularly, ROA spectroscopy of the native OCPR provides a direct support for the 12 Å translocation of chromophore in the photoactivation, which was proposed by X-ray crystallography using RCP [R. L. Leverenz, M. Sutter, et al. Science 2015, 348, 1463-1466].
Collapse
Affiliation(s)
- Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Saga 850-8502, Japan
| | - Ryan L Leverenz
- MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Momoka Nagamine
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Saga 850-8502, Japan
| | - Cheryl A Kerfeld
- MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, Michigan 48824, United States.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Saga 850-8502, Japan
| |
Collapse
|
11
|
Orange carotenoid protein burrows into the phycobilisome to provide photoprotection. Proc Natl Acad Sci U S A 2016; 113:E1655-62. [PMID: 26957606 DOI: 10.1073/pnas.1523680113] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In cyanobacteria, photoprotection from overexcitation of photochemical centers can be obtained by excitation energy dissipation at the level of the phycobilisome (PBS), the cyanobacterial antenna, induced by the orange carotenoid protein (OCP). A single photoactivated OCP bound to the core of the PBS affords almost total energy dissipation. The precise mechanism of OCP energy dissipation is yet to be fully determined, and one question is how the carotenoid can approach any core phycocyanobilin chromophore at a distance that can promote efficient energy quenching. We have performed intersubunit cross-linking using glutaraldehyde of the OCP and PBS followed by liquid chromatography coupled to tandem mass spectrometry (LC/MS-MS) to identify cross-linked residues. The only residues of the OCP that cross-link with the PBS are situated in the linker region, between the N- and C-terminal domains and a single C-terminal residue. These links have enabled us to construct a model of the site of OCP binding that differs from previous models. We suggest that the N-terminal domain of the OCP burrows tightly into the PBS while leaving the OCP C-terminal domain on the exterior of the complex. Further analysis shows that the position of the small core linker protein ApcC is shifted within the cylinder cavity, serving to stabilize the interaction between the OCP and the PBS. This is confirmed by a ΔApcC mutant. Penetration of the N-terminal domain can bring the OCP carotenoid to within 5-10 Å of core chromophores; however, alteration of the core structure may be the actual source of energy dissipation.
Collapse
|