1
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Takeuchi K, Che Y, Nakano T, Miyake C, Ifuku K. The ability of P700 oxidation in photosystem I reflects chilling stress tolerance in cucumber. JOURNAL OF PLANT RESEARCH 2022; 135:681-692. [PMID: 35767130 DOI: 10.1007/s10265-022-01404-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
Low temperature inhibits photosynthesis and negatively affects plant growth. Cucumber (Cucumis sativus L.) is a chilling-sensitive plant, and its greenhouse production requires considerable energy during the winter. Therefore, a useful stress marker for selecting chilling-tolerant cucumber cultivars is desirable. In this study, we evaluated chilling-stress damage in different cucumber cultivars by measuring photosynthetic parameters. The majority of cultivars showed decreases in the quantum yield of photosystem (PS) II [Fv/Fm and Y(II)] and the quantity of active PS I (Pm) after chilling stress. In contrast, Y(ND)-the ratio of the oxidized state of PSI reaction center chlorophyll P700 (P700+)-differed among cultivars and was perfectly inversely correlated with Y(NA)-the ratio of the non-photooxidizable P700. It has been known that P700+ accumulates under stress conditions and protects plants to suppress the generation of reactive oxygen species. In fact, cultivars unable to induce Y(ND) after chilling stress showed growth retardation with reductions in chlorophyll content and leaf area. Therefore, Y(ND) can be a useful marker to evaluate chilling-stress tolerance in cucumber.
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Affiliation(s)
- Ko Takeuchi
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Yufen Che
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Takeshi Nakano
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Chikahiro Miyake
- Graduate School of Agriculture, Kobe University, Kobe, Hyogo, Japan
| | - Kentaro Ifuku
- Graduate School of Agriculture, Kyoto University, Kitashirakawa oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.
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2
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Pashayeva A, Wu G, Huseynova I, Lee CH, Zulfugarov IS. Role of Thylakoid Protein Phosphorylation in Energy-Dependent Quenching of Chlorophyll Fluorescence in Rice Plants. Int J Mol Sci 2021; 22:ijms22157978. [PMID: 34360743 PMCID: PMC8347447 DOI: 10.3390/ijms22157978] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/18/2021] [Accepted: 07/23/2021] [Indexed: 11/16/2022] Open
Abstract
Under natural environments, light quality and quantity are extremely varied. To respond and acclimate to such changes, plants have developed a multiplicity of molecular regulatory mechanisms. Non-photochemical quenching of chlorophyll fluorescence (NPQ) and thylakoid protein phosphorylation are two mechanisms that protect vascular plants. To clarify the role of thylakoid protein phosphorylation in energy-dependent quenching of chlorophyll fluorescence (qE) in rice plants, we used a direct Western blot assay after BN-PAGE to detect all phosphoproteins by P-Thr antibody as well as by P-Lhcb1 and P-Lhcb2 antibodies. Isolated thylakoids in either the dark- or the light-adapted state from wild type (WT) and PsbS-KO rice plants were used for this approach to detect light-dependent interactions between PsbS, PSII, and LHCII proteins. We observed that the bands corresponding to the phosphorylated Lhcb1 and Lhcb2 as well as the other phosphorylated proteins were enhanced in the PsbS-KO mutant after illumination. The qE relaxation became slower in WT plants after 10 min HL treatment, which correlated with Lhcb1 and Lhcb2 protein phosphorylation in the LHCII trimers under the same experimental conditions. Thus, we concluded that light-induced phosphorylation of PSII core and Lhcb1/Lhcb2 proteins is enhanced in rice PsbS-KO plants which might be due to more reactive-oxygen-species production in this mutant.
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Affiliation(s)
- Aynura Pashayeva
- Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences, 11 Izzat Nabiyev Str., Baku AZ 1073, Azerbaijan; (A.P.); (I.H.)
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 46241, Korea;
| | - Guangxi Wu
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 46241, Korea;
| | - Irada Huseynova
- Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences, 11 Izzat Nabiyev Str., Baku AZ 1073, Azerbaijan; (A.P.); (I.H.)
| | - Choon-Hwan Lee
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 46241, Korea;
- Correspondence: (C.-H.L.); or (I.S.Z.)
| | - Ismayil S. Zulfugarov
- Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences, 11 Izzat Nabiyev Str., Baku AZ 1073, Azerbaijan; (A.P.); (I.H.)
- Correspondence: (C.-H.L.); or (I.S.Z.)
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3
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Betterle N, Poudyal RS, Rosa A, Wu G, Bassi R, Lee CH. The STN8 kinase-PBCP phosphatase system is responsible for high-light-induced reversible phosphorylation of the PSII inner antenna subunit CP29 in rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 89:681-691. [PMID: 27813190 DOI: 10.1111/tpj.13412] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 10/24/2016] [Accepted: 10/28/2016] [Indexed: 05/22/2023]
Abstract
Reversible phosphorylation of thylakoid light-harvesting proteins is a mechanism to compensate for unbalanced excitation of photosystem I (PSI) versus photosystem II (PSII) under limiting light. In monocots, an additional phosphorylation event on the PSII antenna CP29 occurs upon exposure to excess light, enhancing resistance to light stress. Different from the case of the major LHCII antenna complex, the STN7 kinase and its related PPH1 phosphatase were proven not to be involved in CP29 phosphorylation, indicating that a different set of enzymes act in the high-light (HL) response. Here, we analyze a rice stn8 mutant in which both PSII core proteins and CP29 phosphorylation are suppressed in HL, implying that STN8 is the kinase catalyzing this reaction. In order to identify the phosphatase involved, we produced a recombinant enzyme encoded by the rice ortholog of AtPBCP, antagonist of AtSTN8, which catalyzes the dephosphorylation of PSII core proteins. The recombinant protein was active in dephosphorylating P-CP29. Based on these data, we propose that the activities of the OsSTN8 kinase and the antagonistic OsPBCP phosphatase, in addition to being involved in the repair of photo-damaged PSII, are also responsible for the HL-dependent reversible phosphorylation of the inner antenna CP29.
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Affiliation(s)
- Nico Betterle
- Dipartimento di Biotecnologie, Università di Verona, Ca' Vignal 1, Strada le Grazie 15, Verona, 37134, Italy
| | | | - Anthony Rosa
- Dipartimento di Biotecnologie, Università di Verona, Ca' Vignal 1, Strada le Grazie 15, Verona, 37134, Italy
| | - Guangxi Wu
- Department of Molecular Biology, Pusan National University, Busan, 609-735, Korea
| | - Roberto Bassi
- Dipartimento di Biotecnologie, Università di Verona, Ca' Vignal 1, Strada le Grazie 15, Verona, 37134, Italy
| | - Choon-Hwan Lee
- Department of Molecular Biology, Pusan National University, Busan, 609-735, Korea
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Tovuu A, Zulfugarov IS, Wu G, Kang IS, Kim C, Moon BY, An G, Lee CH. Rice mutants deficient in ω-3 fatty acid desaturase (FAD8) fail to acclimate to cold temperatures. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 109:525-535. [PMID: 27835850 DOI: 10.1016/j.plaphy.2016.11.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 05/24/2023]
Abstract
To investigate the role of ω-3 fatty acid (FA) desaturase (FAD8) during cold acclimation in higher plants, we characterized three independent T-DNA insertional knock-out mutants of OsFAD8 from rice (Oryza sativa L.). At room temperature (28 °C), osfad8 plants exhibited significant alterations in fatty acid (FA) unsaturation for all four investigated plastidic lipid classes. During a 5-d acclimation period at 4 °C, further changes in FA unsaturation in both wild-type (WT) and mutant plants varied according to the type of lipid. We also monitored the fluidity of the thylakoid membrane using a threshold temperature to represent the change in fluorescence. The values were altered significantly by both FAD8 mutation and cold acclimation, suggesting that factors other than FAD8 are involved in C18 FA unsaturation and fluctuations in membrane fluidity. Similarly, significant changes were noted for both the mutant and WT samples in terms of their FA compositions as well as activities related to photosystem (PS) I, PSII, and photoprotection. This included the development of non-photochemical quenching and increased zeaxanthin accumulation. Despite the relatively small changes in FA composition during cold acclimation, cold-inducible FAD8 knock-out mutants displayed strong differences in photoprotective activities and a further drop in membrane fluidity. The mutants were more sensitive than WT to short-term low-temperature stress that resulted in increased production of reactive oxygen species after 5 d of chilling. Taken together, our findings suggest that FA unsaturation by OsFAD8 is crucial for the acclimation of higher plants to low-temperature stress.
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Affiliation(s)
- Altanzaya Tovuu
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 609-735, Republic of Korea; Department of Biotechnology, Breeding, Mongolian University of Life Sciences, Zaisan 17024, Ulaanbaatar, Mongolia
| | - Ismayil S Zulfugarov
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 609-735, Republic of Korea; Department of Biology, North-Eastern Federal University, 58 Belinsky Str., Yakutsk 677-027, Republic of Sakha (Yakutia), Russian Federation; Institute of Molecular Biology and Biotechnology, Azerbaijan National Academy of Sciences, Matbuat Avenue 2a, Baku, AZ 1073, Azerbaijan
| | - Guangxi Wu
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 609-735, Republic of Korea
| | - In Soon Kang
- Department of Biological Sciences, Inje University, Gimhae 621-749, Republic of Korea; Department of Pharmacology, School of Medicine, Inha University, Incheon 22212, Republic of Korea
| | - Choongrak Kim
- Department of Statistics, Pusan National University, Busan 609-735, Republic of Korea
| | - Byoung Yong Moon
- Department of Biological Sciences, Inje University, Gimhae 621-749, Republic of Korea
| | - Gynheung An
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Republic of Korea
| | - Choon-Hwan Lee
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 609-735, Republic of Korea.
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5
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Production of superoxide from photosystem II-light harvesting complex II supercomplex in STN8 kinase knock-out rice mutants under photoinhibitory illumination. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2016; 162:240-247. [PMID: 27390892 DOI: 10.1016/j.jphotobiol.2016.06.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/28/2016] [Indexed: 01/19/2023]
Abstract
When phosphorylation of Photosystem (PS) II core proteins is blocked in STN8 knock-out mutants of rice (Oryza sativa) under photoinhibitory illumination, the mobilization of PSII supercomplex is prevented. We have previously proposed that more superoxide (O2(-)) is produced from PSII in the mutant (Nath et al., 2013, Plant J. 76, 675-686). Here, we clarify the type and site for the generation of reactive oxygen species (ROS). Using both histochemical and fluorescence probes, we observed that, compared with wild-type (WT) leaves, levels of ROS, including O2(-) and hydrogen peroxide (H2O2), were increased when leaves from mutant plants were illuminated with excess light. However, singlet oxygen production was not enhanced under such conditions. When superoxide dismutase was inhibited, O2(-) production was increased, indicating that it is the initial event prior to H2O2 production. In thylakoids isolated from WT leaves, kinase was active in the presence of ATP, and spectrophotometric analysis of nitrobluetetrazolium absorbance for O2(-) confirmed that PSII-driven superoxide production was greater in the mutant thylakoids than in the WT. This contrast in levels of PSII-driven superoxide production between the mutants and the WT plants was confirmed by conducting protein oxidation assays of PSII particles from osstn8 leaves under strong illumination. Those assays also demonstrated that PSII-LHCII supercomplex proteins were oxidized more in the mutant, thereby implying that PSII particles incur greater damage even though D1 degradation during PSII-supercomplex mobilization is partially blocked in the mutant. These results suggest that O2(-) is the major form of ROS produced in the mutant, and that the damaged PSII in the supercomplex is the primary source of O2(-).
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6
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Yaakoubi H, Hamdani S, Bekalé L, Carpentier R. Protective action of spermine and spermidine against photoinhibition of photosystem I in isolated thylakoid membranes. PLoS One 2014; 9:e112893. [PMID: 25420109 PMCID: PMC4242612 DOI: 10.1371/journal.pone.0112893] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 10/16/2014] [Indexed: 11/18/2022] Open
Abstract
The photo-stability of photosystem I (PSI) is of high importance for the photosynthetic processes. For this reason, we studied the protective action of two biogenic polyamines (PAs) spermine (Spm) and spermidine (Spd) on PSI activity in isolated thylakoid membranes subjected to photoinhibition. Our results show that pre-loading thylakoid membranes with Spm and Spd reduced considerably the inhibition of O2 uptake rates, P700 photooxidation and the accumulation of superoxide anions (O2(-)) induced by light stress. Spm seems to be more effective than Spd in preserving PSI photo-stability. The correlation of the extent of PSI protection, photosystem II (PSII) inhibition and O2(-) generation with increasing Spm doses revealed that PSI photo-protection is assumed by two mechanisms depending on the PAs concentration. Given their antioxidant character, PAs scavenge directly the O2(-) generated in thylakoid membranes at physiological concentration (1 mM). However, for non-physiological concentration, the ability of PAs to protect PSI is due to their inhibitory effect on PSII electron transfer.
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Affiliation(s)
- Hnia Yaakoubi
- Groupe de Recherche en Biologie-Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Saber Hamdani
- Groupe de Recherche en Biologie-Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Laurent Bekalé
- Groupe de Recherche en Biologie-Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Robert Carpentier
- Groupe de Recherche en Biologie-Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
- * E-mail:
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7
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Zulfugarov IS, Tovuu A, Lee CH. Acceleration of cyclic electron flow in rice plants (Oryza sativa L.) deficient in the PsbS protein of Photosystem II. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 84:233-239. [PMID: 25306526 DOI: 10.1016/j.plaphy.2014.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 10/01/2014] [Indexed: 05/08/2023]
Abstract
When compared with Photosystem I (PSI) in wild-type (WT) rice plants, PSI in PsbS-knockout (KO) plants that lack the energy-dependent component of nonphotochemical quenching (NPQ) was less sensitive to photoinhibition. Therefore, we investigated the relationship between NPQ and cyclic electron flow (CEF) around PSI as a photoprotective mechanism. Activities of two CEF routes (PGR5-dependent or NDH-dependent) were compared between those genotypes by using both dark-adapted plants and pre-illuminated plants, i.e., those in which the Calvin-Benson cycle is de-activated and activated, respectively. In dark-adapted leaves activity of the PGR5-dependent route was determined as the rate of P700 photooxidation. Activity was higher in the mutants than in the WT. However, no difference was noted when plants of either genotype were pre-illuminated. When the electron transport pathway was switched to the cyclic mode by infiltrating leaf segments with 150 mM sorbitol, 40 μM DCMU, and 2 mM hydroxylamine, the rate of P700 oxidation was faster in the mutant. That difference disappeared when leaves were infiltrated with antimycin A to inhibit the PGR5-dependent route. Chlorophyll fluorescence (Fo) was also evaluated. To achieve an Fo level comparable to that of the WT, activation of the NDH-dependent route in the mutant required pre-illumination at a certain dose. Therefore, we propose that, as an alternate pathway for the photoprotection of photosystems in the absence of energy-dependent quenching, this PGR5-dependent route is more highly activated in the PsbS-KO mutants than in the WT. Moreover, that stronger activity is probably responsible for slower activation of the NDH-dependent route in the mutant.
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Affiliation(s)
- Ismayil S Zulfugarov
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735, Republic of Korea; Department of Biology, North-Eastern Federal University, 58 Belinsky Str., Yakutsk 677-027 Republic of Sakha (Yakutia), Russian Federation; Institute of Botany, Azerbaijan National Academy of Sciences, Patamdar Shosse 40, Baku, AZ 1073, Azerbaijan.
| | - Altanzaya Tovuu
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735, Republic of Korea; Department of Biology, Mongolian State University of Agriculture, Zaisan, 17024 Ulaanbaatar, Mongolia.
| | - Choon-Hwan Lee
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735, Republic of Korea.
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Abstract
In oxygenic photosynthetic eukaryotes, the hydroxylated carotenoid zeaxanthin is produced from preexisting violaxanthin upon exposure to excess light conditions. Zeaxanthin binding to components of the photosystem II (PSII) antenna system has been investigated thoroughly and shown to help in the dissipation of excess chlorophyll-excited states and scavenging of oxygen radicals. However, the functional consequences of the accumulation of the light-harvesting complex I (LHCI) proteins in the photosystem I (PSI) antenna have remained unclarified so far. In this work we investigated the effect of zeaxanthin binding on photoprotection of PSI-LHCI by comparing preparations isolated from wild-type Arabidopsis thaliana (i.e., with violaxanthin) and those isolated from the A. thaliana nonphotochemical quenching 2 mutant, in which violaxanthin is replaced by zeaxanthin. Time-resolved fluorescence measurements showed that zeaxanthin binding leads to a previously unrecognized quenching effect on PSI-LHCI fluorescence. The efficiency of energy transfer from the LHCI moiety of the complex to the PSI reaction center was down-regulated, and an enhanced PSI resistance to photoinhibition was observed both in vitro and in vivo. Thus, zeaxanthin was shown to be effective in inducing dissipative states in PSI, similar to its well-known effect on PSII. We propose that, upon acclimation to high light, PSI-LHCI changes its light-harvesting efficiency by a zeaxanthin-dependent quenching of the absorbed excitation energy, whereas in PSII the stoichiometry of LHC antenna proteins per reaction center is reduced directly.
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Trans-thylakoid ∆pH dependent oscillation of F(PSI)/F(PSII) under continuous irradiance in isolated thylakoids. J Bioenerg Biomembr 2013; 46:71-82. [PMID: 24214386 DOI: 10.1007/s10863-013-9533-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 10/10/2013] [Indexed: 10/26/2022]
Abstract
Energy distribution between photosystems (PSI & PSII) under prolonged and continuous white light irradiance was assessed by monitoring the progress of their fluorescence emission (FPSI/FPSII) at 77 K. Our observations indicate FPSI/FPSII to oscillate with the progress of irradiance treatments at all intensities tested (100, 200, 500, and 800 μE m(-2) S(-1)). The amplitude of the oscillation increased with the progress, whereas the periodicity of the oscillation increased with the intensity of the incident irradiance. Spectral analysis indicated fluctuation of FPSI to be the major determinant of the observed oscillation. The first rise and fall of FPSI/FPSII overlapped with phosphorylation and dephosphorylation of LHCII, but oscillation of FPSI/FPSII continued for several cycles without any further phosphorylation of LHCII. Moreover, in presence of DCMU where linear electron flow (LEF) is suppressed and LHCII phosphorylation is completely abolished, the oscillation of FPSI/FPSII was not abolished. These data indicated that LHCII phosphorylation was not essential for the observed oscillation of energy distribution between the photosystems. In contrast, in the presence of inhibitors of cyclic electron flow (CEF) like Antimycin A (AA) and rotenone, the oscillation of FPSI/FPSII was either abolished or severely dampened. Additionally, the oscillation was also abolished in presence of uncouplers like NH4Cl and nigericin that cancels the trans-thylakoid ∆pH. Thus, trans-thylakoid ∆pH, generated through CEF, appear to be an important determinant of oscillation of FPSI/FPSII in isolated thylakoids. The phenomenon of oscillation could be associated with a CEF mediated chromatic adaptation of PSI in presence of excess irradiance.
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10
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Nath K, Poudyal RS, Eom JS, Park YS, Zulfugarov IS, Mishra SR, Tovuu A, Ryoo N, Yoon HS, Nam HG, An G, Jeon JS, Lee CH. Loss-of-function of OsSTN8 suppresses the photosystem II core protein phosphorylation and interferes with the photosystem II repair mechanism in rice (Oryza sativa). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 76:675-86. [PMID: 24103067 DOI: 10.1111/tpj.12331] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 08/07/2013] [Accepted: 09/02/2013] [Indexed: 05/10/2023]
Abstract
STN8 kinase is involved in photosystem II (PSII) core protein phosphorylation (PCPP). To examine the role of PCPP in PSII repair during high light (HL) illumination, we characterized a T-DNA insertional knockout mutant of the rice (Oryza sativa) STN8 gene. In this osstn8 mutant, PCPP was significantly suppressed, and the grana were thin and elongated. Upon HL illumination, PSII was strongly inactivated in the mutants, but the D1 protein was degraded more slowly than in wild-type, and mobilization of the PSII supercomplexes from the grana to the stromal lamellae for repair was also suppressed. In addition, higher accumulation of reactive oxygen species and preferential oxidation of PSII reaction center core proteins in thylakoid membranes were observed in the mutants during HL illumination. Taken together, our current data show that the absence of STN8 is sufficient to abolish PCPP in osstn8 mutants and to produce all of the phenotypes observed in the double mutant of Arabidopsis, indicating the essential role of STN8-mediated PCPP in PSII repair.
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Affiliation(s)
- Krishna Nath
- Department of Molecular Biology, Pusan National University, Busan, 609-735, Korea; Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu, 711-873, Korea
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Krech K, Ruf S, Masduki FF, Thiele W, Bednarczyk D, Albus CA, Tiller N, Hasse C, Schöttler MA, Bock R. The plastid genome-encoded Ycf4 protein functions as a nonessential assembly factor for photosystem I in higher plants. PLANT PHYSIOLOGY 2012; 159:579-91. [PMID: 22517411 PMCID: PMC3375926 DOI: 10.1104/pp.112.196642] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/17/2012] [Indexed: 05/18/2023]
Abstract
Photosystem biogenesis in the thylakoid membrane is a highly complicated process that requires the coordinated assembly of nucleus-encoded and chloroplast-encoded protein subunits as well as the insertion of hundreds of cofactors, such as chromophores (chlorophylls, carotenoids) and iron-sulfur clusters. The molecular details of the assembly process and the identity and functions of the auxiliary factors involved in it are only poorly understood. In this work, we have characterized the chloroplast genome-encoded ycf4 (for hypothetical chloroplast reading frame no. 4) gene, previously shown to encode a protein involved in photosystem I (PSI) biogenesis in the unicellular green alga Chlamydomonas reinhardtii. Using stable transformation of the chloroplast genome, we have generated ycf4 knockout plants in the higher plant tobacco (Nicotiana tabacum). Although these mutants are severely affected in their photosynthetic performance, they are capable of photoautotrophic growth, demonstrating that, different from Chlamydomonas, the ycf4 gene product is not essential for photosynthesis. We further show that ycf4 knockout plants are specifically deficient in PSI accumulation. Unaltered expression of plastid-encoded PSI genes and biochemical analyses suggest a posttranslational action of the Ycf4 protein in the PSI assembly process. With increasing leaf age, the contents of Ycf4 and Y3IP1, another auxiliary factor involved in PSI assembly, decrease strongly, whereas PSI contents remain constant, suggesting that PSI is highly stable and that its biogenesis is restricted to young leaves.
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Affiliation(s)
- Katharina Krech
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
| | - Stephanie Ruf
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
| | - Fifi F. Masduki
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
| | - Wolfram Thiele
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
| | | | - Christin A. Albus
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
| | - Nadine Tiller
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
| | - Claudia Hasse
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
| | - Mark A. Schöttler
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany
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Abstract
The photoinhibition of Photosystem I (PSI) drew less attention compared with that of Photosystem II (PSII). This could be ascribed to several reasons, e.g. limited combinations of plant species and environmental conditions that cause PSI photoinhibition, the non-regulatory aspect of PSI photoinhibition, and methodological difficulty to determine the accurate activity of PSI under stress conditions. However, the photoinhibition of PSI could be more dangerous than that of PSII because of the very slow recovery rate of PSI. This article is intended to introduce such characteristics of PSI photoinhibition with special emphasis on the relationship between two photosystems as well as the protective mechanism of PSI in vivo. Although the photoinhibition of PSI could be induced only in specific conditions and specific plant species in intact leaves, PSI itself is quite susceptible to photoinhibition in isolated thylakoid membranes. PSI seems to be well protected from photoinhibition in vivo in many plant species and many environmental conditions. This is quite understandable because photoinhibition of PSI is not only irreversible but also the potential cause of many secondary damages. This point would be different from the case of PSII photoinhibition, which could be regarded as one of the regulatory mechanisms under stressed as well as non-stressed conditions.
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Affiliation(s)
- Kintake Sonoike
- Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.
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