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- 저자 : Zulfugarov, (검색결과 23 건)
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Zulfugarov Ismayil S.,Mishra Sujata R.,Han, Ok-Kyung,Safarova Rena B.,Nath Krishna,Lee, Choon-Hwan Korean Society of Photoscience 2005 Journal of Photosciences Vol.12 No.3
Plants dissipate excess excitation energy from their photosynthetic apparatus by a process called non-photochemical quenching (NPQ). The major part of NPQ is energy dependent quenching (qE) which is dependent on the thylakoid pH and regulated by xanthophyll cycle carotenoids associated with photosystem (PS) II of higher plants. The acidification of the lumen leads to protonation and thus conformational change of light harvesting complex (LHC) proteins as well as PsbS protein of PSII, which results in the induction of qE. Although physiological importance of qE has been well established, the mechanistic understanding is rather insufficient. However, recent finding of crystal structure of LHCII trimer and identification of qE mutants in higher plants and algae enrich and sharpen our understanding of this process. This review summarizes our current knowledge on the qE mechanism. The nature of quenching sites and components involved in this process, and their contribution and interaction for the generation of qE appeared in the proposed models for the qE mechanism are discussed.
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Zulfugarov, Ismayil S.,Tovuu, Altanzaya,Dogsom, Bolormaa,Lee, Chung Yeol,Lee, Choon-Hwan Royal Society of Chemistry 2010 Photochemical & photobiological sciences Vol.9 No.5
<P>The PsbS protein of photosystem II is necessary for the development of energy-dependent quenching of chlorophyll (Chl) fluorescence (qE), and PsbS-deficient <I>Arabidopsis</I> plant leaves failed to show qE-specific changes in the steady-state 77 K fluorescence emission spectra observed in wild-type leaves. The difference spectrum between the quenched and un-quenched states showed a negative peak at 682 nm. Although the level of qE development in the zeaxanthin-less <I>npq1</I>-<I>2</I> mutant plants, which lacked violaxanthin de-epoxidase enzyme, was only half that of wild type, there were no noticeable changes in this qE-dependent difference spectrum. This zeaxanthin-independent ΔF682 signal was not dependent on state transition, and the signal was not due to photobleaching of pigments either. These results suggest that ΔF682 signal is formed due to PsbS-specific conformational changes in the quenching site of qE and is a new signature of qE generation in higher plants.</P> <P>Graphic Abstract</P><P>The PsbS-specific zeaxanthin-independent ΔF682 signal in 77 K fluorescence emission spectrum was formed due to PsbS-specific conformational changes in the quenching site of qE and is a new signature of qE generation in higher plants that is dependent neither on state transition nor on photobleaching of pigments. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b9pp00132h'> </P>
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Enhanced resistance of PsbS-deficient rice (Oryza sativa L.) to fungal and bacterial pathogens
Ismayil S. Zulfugarov,Altanzaya Tovuu,김치열,Kieu Thi Xuan Vo,고수연,Michael Hall,석혜연,김연기,Oscar Skogstrom,문용환,Stefan Jansson,전종성,이춘환 한국식물학회 2016 Journal of Plant Biology Vol.59 No.6
The 22-kDa PsbS protein of Photosystem II is involved in nonphotochemical quenching (NPQ) of chlorophyll fluorescence. Genome-wide analysis of the expression pattern in PsbS knockout (KO) rice plants showed that a lack of this protein led to changes in the transcript levels of 406 genes, presumably a result of superoxide produced in the chloroplasts. The top Gene Ontology categories, in which expression was the most differential, included ‘Immune response’, ‘Response to jasmonic acid’, and ‘MAPK cascade’. From those genes, we randomly selected nine that were up-regulated. Our microarray results were confirmed by quantitative RT-PCR analysis. The KO and PsbS RNAi (knockdown) plants were more resistant to pathogens Magnaporthe oryzae PO6-6 and Xanthomonas oryzae pv. oryzae than either the wild-type plants or PsbS-overexpressing transgenic line. These findings suggest that superoxide production might be the reason that these plants have greater pathogen resistance to fungal and bacterial pathogens in the absence of energy-dependent NPQ. For example, a high level of cell wall lignification in the KO mutants was possibly due to enhanced superoxide production. Our data indicate that certain abiotic stress-induced reactive oxygen species can promote specific signaling pathways, which then activate a defense mechanism against biotic stress in PsbS-KO rice plants.
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Detection of Reactive Oxygen Species in Higher Plants
Ismayil S. Zulfugarov,Altanzaya Tovuu,Jin-Hong Kim,이춘환 한국식물학회 2011 Journal of Plant Biology Vol.54 No.6
Formed during the reduction of molecular oxygen or water oxidation, reactive oxygen species (ROS) are produced by a variety of enzymes and redox reactions in almost every compartment of the plant cell. In addition to causing cellular damage, these ROS play a role in signaling networks. Many factors contribute to and, simultaneously,control their metabolism, and it is difficult to detect individual ROS accurately. This is due to several challenges inherent to ROS—their relatively short half-lives, low intracellular concentrations, enzymatic and non-enzymatic scavenging capacity of the cells, and the absence of absolutely selective probes for ROS. Here, we describe the common approaches taken for detecting primary ROS,singlet oxygen, superoxide, and hydrogen peroxide as we discuss their advantages and limitations. We can conclude that using two or more independent methods that yield similar results for detection is a reliable means for studying ROS in intact plant tissues.
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Tovuu, Altanzaya,Zulfugarov, Ismayil S.,Lee, Choon‐,Hwan Blackwell Publishing Ltd 2013 Physiologia Plantarum Vol.147 No.4
<P>To monitor changes in membrane fluidity in Arabidopsis leaves and thylakoid membranes, we investigated the temperature dependence of a chlorophyll fluorescence parameter, minimum fluorescence (Fo), and calculated the threshold temperature [T(Fo)] at which the rise of the fluorescence level Fo was considered to be started. For the modification of membrane fluidity we took three different approaches: (1) an examination of wild‐type leaves initially cultured at room temperature (22°C), then exposed to either a lower (4°C) or higher (35°C) temperature for 5 days; (2) measurements of the shift in T(Fo) by two mutants deficient in fatty acid desaturase genes – <I>fad7</I> and <I>fad7fad8</I> and (3) an evaluation of the performance of wild‐type plants when leaves were infiltrated with chemicals that modify fluidity. When wild‐type plants were grown at 22°C, the T(Fo) was 48.3 ± 0.3°C. Plants that were then transferred to a chamber set at 4 or 35°C showed a shift in their T(Fo) to 42.7 ± 0.9°C or 48.9 ± 0.1°C, respectively. Under low‐temperature acclimation, the decline in this putative transition temperature was significantly less in <I>fad7</I> and <I>fad7fad8</I> mutants compared with the wild‐type. In both leaf and thylakoid samples, values for T(Fo) were reduced in samples treated with benzyl alcohol, a membrane fluidizer, whereas T(Fo) rose in samples treated with dimethylsulfoxide, a membrane rigidifier. These results indicate that the heat‐induced rise of chlorophyll fluorescence is strongly correlated with the fluidity of thylakoid membranes.</P>
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Rice mutants deficient in ω-3 fatty acid desaturase (FAD8) fail to acclimate to cold temperatures
Tovuu, A.,Zulfugarov, I.S.,Wu, G.,Kang, I.S.,Kim, C.,Moon, B.Y.,An, G.,Lee, C.H. Elsevier Science B.V., Amsterdam. 2016 Plant Physiology and Biochemistry Vol. No.
<P>To investigate the role of omega-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 degrees 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 degrees 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. (C) 2016 Elsevier Masson SAS. All rights reserved.</P>
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( Eun Kyeong Song ),( Ismayil S. Zulfugarov ),( Jin Hong Kim ),( Eun Ha Kim ),( Woo Sung Lee ),( Choon Hwan Lee ) 한국식물학회 2004 Journal of Plant Biology Vol.47 No.4
We compared several analytical tools to identify which were most applicable for the selection and characterization of specific transposon-tagged mutant strains of Synechocystis sp. PCC 6803 that are sensitive to high light and oxidative stresses. Our primary parameter was the maximum photochemical efficiency of dark-adapted cells, a very sensitive factor that can be determined in a non-destructive manner. Using this as a tool for primary selection, we identified five mutant strains with different sensitivities to photoinhibition and photooxidation. For further characterization, we obtained data describing the absorption spectra for pigment contents, the 77 K fluorescence spectra, non-photochemical quenching (as a down-regulation process), and the photosynthetic electron transfer rate. Based on these results, we were able to design a strategy for selecting mutants with specific phenotypes. Here, we also discuss the strengths and weaknesses of each selection and characterization tool.
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Shin, Jieun,Kim, Keunhwa,Kang, Hyojin,Zulfugarov, Ismayil S,Bae, Gabyong,Lee, Choon-Hwan,Lee, Doheon,Choi, Giltsu National Academy of Sciences 2009 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.106 No.18
<P>PIF3 is a phytochrome-interacting basic helix-loop-helix transcription factor that negatively regulates light responses, including hypocotyl elongation, cotyledon opening, and hypocotyl negative gravitropism. However, the role of PIF3 in chlorophyll biosynthesis has not been clearly defined. Here, we show that PIF3 also negatively regulates chlorophyll biosynthesis by repressing biosynthetic genes in the dark. Consistent with the gene expression patterns, the etiolated pif3 mutant accumulated a higher amount of protochlorophyllide and was bleached severely when transferred into light. The photobleaching phenotype of pif3 could be suppressed by the gun5 mutation and mimicked by overexpression of GUN5. When 4 negative phytochrome-interacting protein genes (PIF1, PIF3, PIF4, and PIF5) were mutated, the resulting quadruple mutant seedlings displayed constitutive photomorphogenic phenotypes, including short hypocotyls, open cotyledons, and disrupted hypocotyl gravitropism in the dark. Microarray analysis further confirmed that the dark-grown quadruple mutant has a gene expression pattern similar to that of red light-grown WT. Together, our data indicate that 4 phytochrome-interacting proteins are required for skotomorphogenesis and phytochromes activate photomorphogenesis by inhibiting these factors.</P>
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