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Wan Y, Tang K, Zhang D, Xie S, Zhu X, Wang Z, Lang Z. Transcriptome-wide high-throughput deep m(6)A-seq reveals unique differential m(6)A methylation patterns between three organs in Arabidopsis thaliana. Genome Biol 2015; 16:272. [PMID: 26667818 PMCID: PMC4714525 DOI: 10.1186/s13059-015-0839-2] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 11/18/2015] [Indexed: 12/25/2022] Open
Abstract
Background m6A is a ubiquitous RNA modification in eukaryotes. Transcriptome-wide m6A patterns in Arabidopsis have been assayed recently. However, differential m6A patterns between organs have not been well characterized. Results Over two-third of the transcripts in Arabidopsis are modified by m6A. In contrast to a recent observation of m6A enrichment in 5′ mRNA, we find that m6A is distributed predominantly near stop codons. Interestingly, 85 % of the modified transcripts show high m6A methylation extent compared to their transcript level. The 290 highly methylated transcripts are mainly associated with transporters, stress responses, redox, regulation factors, and some non-coding RNAs. On average, the proportion of transcripts showing differential methylation between two plant organs is higher than that showing differential transcript levels. The transcripts with extensively higher m6A methylation in an organ are associated with the unique biological processes of this organ, suggesting that m6A may be another important contributor to organ differentiation in Arabidopsis. Highly expressed genes are relatively less methylated and vice versa, and different RNAs have distinct m6A patterns, which hint at mRNA fate. Intriguingly, most of the transposable element transcripts maintained a fragmented form with a relatively low transcript level and high m6A methylation in the cells. Conclusions This is the first study to comprehensively analyze m6A patterns in a variety of RNAs, the relationship between transcript level and m6A methylation extent, and differential m6A patterns across organs in Arabidopsis. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0839-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yizhen Wan
- State Key Lab Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China. .,Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA.
| | - Kai Tang
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA
| | - Dayong Zhang
- Institute of Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - Shaojun Xie
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA.,Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Xiaohong Zhu
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA.,Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Zegang Wang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, 225009, China
| | - Zhaobo Lang
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA. .,Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
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Dattolo E, Ruocco M, Brunet C, Lorenti M, Lauritano C, D'Esposito D, De Luca P, Sanges R, Mazzuca S, Procaccini G. Response of the seagrass Posidonia oceanica to different light environments: Insights from a combined molecular and photo-physiological study. MARINE ENVIRONMENTAL RESEARCH 2014; 101:225-236. [PMID: 25129449 DOI: 10.1016/j.marenvres.2014.07.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/18/2014] [Accepted: 07/21/2014] [Indexed: 05/03/2023]
Abstract
Here we investigated mechanisms underlying the acclimation to light in the marine angiosperm Posidonia oceanica, along its bathymetric distribution (at -5 m and -25 m), combining molecular and photo-physiological approaches. Analyses were performed during two seasons, summer and autumn, in a meadow located in the Island of Ischia (Gulf of Naples, Italy), where a genetic distinction between plants growing above and below the summer thermocline was previously revealed. At molecular level, analyses carried out using cDNA-microarray and RT-qPCR, revealed the up-regulation of genes involved in photoacclimation (RuBisCO, ferredoxin, chlorophyll binding proteins), and photoprotection (antioxidant enzymes, xanthophyll-cycle related genes, tocopherol biosynthesis) in the upper stand of the meadow, indicating that shallow plants are under stressful light conditions. However, the lack of photo-damage, indicates the successful activation of defense mechanisms. This conclusion is also supported by several responses at physiological level as the lower antenna size, the higher number of reaction centers and the higher xanthophyll cycle pigment pool, which are common plant responses to high-light adaptation/acclimation. Deep plants, despite the lower available light, seem to be not light-limited, thanks to some shade-adaptation strategies (e.g. higher antenna size, lower Ek values). Furthermore, also at the molecular level there were no signs of stress response, indicating that, although the lower energy available, low-light environments are more favorable for P. oceanica growth. Globally, results of whole transcriptome analysis displayed two distinct gene expression signatures related to depth distribution, reflecting the different light-adaptation strategies adopted by P. oceanica along the depth gradient. This observation, also taking into account the genetic disjunction of clones along the bathymetry, might have important implications for micro-evolutionary processes happening at meadow scale. Further investigations in controlled conditions must be performed to respond to these questions.
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Affiliation(s)
- E Dattolo
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy.
| | - M Ruocco
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - C Brunet
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - M Lorenti
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - C Lauritano
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - D D'Esposito
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - P De Luca
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - R Sanges
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - S Mazzuca
- Laboratorio di Proteomica, Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, Arcavacata di Rende 87036, Italy
| | - G Procaccini
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
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Fristedt R, Williams-Carrier R, Merchant SS, Barkan A. A thylakoid membrane protein harboring a DnaJ-type zinc finger domain is required for photosystem I accumulation in plants. J Biol Chem 2014; 289:30657-30667. [PMID: 25228689 DOI: 10.1074/jbc.m114.587758] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Photosystem I (PSI) is a large pigment-protein complex and one of the two photosystems that drive electron transfer in oxygenic photosynthesis. We identified a nuclear gene required specifically for the accumulation of PSI in a forward genetic analysis of chloroplast biogenesis in maize. This gene, designated psa2, belongs to the "GreenCut" gene set, a group of genes found in green algae and plants but not in non-photosynthetic organisms. Disruption of the psa2 ortholog in Arabidopsis likewise resulted in the specific loss of PSI proteins. PSA2 harbors a conserved domain found in DnaJ chaperones where it has been shown to form a zinc finger and to have protein-disulfide isomerase activity. Accordingly, PSA2 exhibited protein-disulfide reductase activity in vitro. PSA2 localized to the thylakoid lumen and was found in a ∼250-kDa complex harboring the peripheral PSI protein PsaG but lacking several core PSI subunits. PSA2 mRNA is coexpressed with mRNAs encoding various proteins involved in the biogenesis of the photosynthetic apparatus with peak expression preceding that of genes encoding structural components. PSA2 protein abundance was not decreased in the absence of PSI but was reduced in the absence of the PSI assembly factor Ycf3. These findings suggest that a complex harboring PSA2 and PsaG mediates thiol transactions in the thylakoid lumen that are important for the assembly of PSI.
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Affiliation(s)
- Rikard Fristedt
- Department of Chemistry and Biochemistry and UCLA, Los Angeles, California 90095; Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095 and
| | | | - Sabeeha S Merchant
- Department of Chemistry and Biochemistry and UCLA, Los Angeles, California 90095; Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095 and
| | - Alice Barkan
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403.
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Powikrowska M, Khrouchtchova A, Martens HJ, Zygadlo-Nielsen A, Melonek J, Schulz A, Krupinska K, Rodermel S, Jensen PE. SVR4 (suppressor of variegation 4) and SVR4-like: two proteins with a role in proper organization of the chloroplast genetic machinery. PHYSIOLOGIA PLANTARUM 2014; 150:477-92. [PMID: 24111559 DOI: 10.1111/ppl.12108] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Revised: 08/26/2013] [Accepted: 09/03/2013] [Indexed: 05/04/2023]
Abstract
SUPPRESSOR OF VARIEGATION 4 (SVR4, also called MRL7) and its homolog SVR4-like (also called MRL7-Like) were originally identified as important proteins for proper function of the chloroplast in Arabidopsis. Both are nuclear-encoded chloroplast-located proteins, and knockout mutants of either gene result in seedling lethality. Transmission electron microscopy analysis revealed that chloroplast development is arrested at an early developmental stage in both mutants. Accordingly, in the mutant plants severely decreased levels of photosynthetic pigments as well as subunits of the photosynthetic complexes could be detected. In absence of either of the two proteins chloroplast DNA organization was clearly affected. Immunological analysis revealed that SVR4 is a component of the transcriptionally active chromosome (TAC) from barley chloroplasts. Analyses of gene expression indicate that SVR4 and SVR4-like are required for proper function of the plastid transcriptional machinery. We propose that SVR4 and SVR4-like function as molecular chaperones ensuring proper organization of the nucleoids in chloroplasts.
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Affiliation(s)
- Marta Powikrowska
- Villum Centre of Excellence "Plant Plasticity" and Center for Synthetic Biology, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871, Frederiksberg C, Denmark
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Ozawa SI, Onishi T, Takahashi Y. Identification and characterization of an assembly intermediate subcomplex of photosystem I in the green alga Chlamydomonas reinhardtii. J Biol Chem 2010; 285:20072-9. [PMID: 20413595 DOI: 10.1074/jbc.m109.098954] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Photosystem I (PSI) is a multiprotein complex consisting of the PSI core and peripheral light-harvesting complex I (LHCI) that together form the PSI-LHCI supercomplex in algae and higher plants. The supercomplex is synthesized in steps during which 12-15 core and 4-9 LHCI subunits are assembled. Here we report the isolation of a PSI subcomplex that separated on a sucrose density gradient from the thylakoid membranes isolated from logarithmic growth phase cells of the green alga Chlamydomonas reinhardtii. Pulse-chase labeling of total cellular proteins revealed that the subcomplex was synthesized de novo within 1 min and was converted to the mature PSI-LHCI during the 2-h chase period, indicating that the subcomplex was an assembly intermediate. The subcomplex was functional; it photo-oxidized P700 and demonstrated electron transfer activity. The subcomplex lacked PsaK and PsaG, however, and it bound PsaF and PsaJ weakly and was not associated with LHCI. It seemed likely that LHCI had been integrated into the subcomplex unstably and was dissociated during solubilization and/or fractionation. We, thus, infer that PsaK and PsaG stabilize the association between PSI core and LHCI complexes and that PsaK and PsaG bind to the PSI core complex after the integration of LHCI in one of the last steps of PSI complex assembly.
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Affiliation(s)
- Shin-Ichiro Ozawa
- Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Kita-ku, Tsushima-naka, Okayama 700-8530, Japan
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Jensen PE, Bassi R, Boekema EJ, Dekker JP, Jansson S, Leister D, Robinson C, Scheller HV. Structure, function and regulation of plant photosystem I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:335-52. [PMID: 17442259 DOI: 10.1016/j.bbabio.2007.03.004] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Revised: 03/03/2007] [Accepted: 03/06/2007] [Indexed: 12/20/2022]
Abstract
Photosystem I (PSI) is a multisubunit protein complex located in the thylakoid membranes of green plants and algae, where it initiates one of the first steps of solar energy conversion by light-driven electron transport. In this review, we discuss recent progress on several topics related to the functioning of the PSI complex, like the protein composition of the complex in the plant Arabidopsis thaliana, the function of these subunits and the mechanism by which nuclear-encoded subunits can be inserted into or transported through the thylakoid membrane. Furthermore, the structure of the native PSI complex in several oxygenic photosynthetic organisms and the role of the chlorophylls and carotenoids in the antenna complexes in light harvesting and photoprotection are reviewed. The special role of the 'red' chlorophylls (chlorophyll molecules that absorb at longer wavelength than the primary electron donor P700) is assessed. The physiology and mechanism of the association of the major light-harvesting complex of photosystem II (LHCII) with PSI during short term adaptation to changes in light quality and quantity is discussed in functional and structural terms. The mechanism of excitation energy transfer between the chlorophylls and the mechanism of primary charge separation is outlined and discussed. Finally, a number of regulatory processes like acclimatory responses and retrograde signalling is reviewed with respect to function of the thylakoid membrane. We finish this review by shortly discussing the perspectives for future research on PSI.
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Affiliation(s)
- Poul Erik Jensen
- Plant Biochemistry Laboratory, Department of Plant Biology, Faculty of Life Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark.
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Zygadlo A, Robinson C, Scheller HV, Mant A, Jensen PE. The properties of the positively charged loop region in PSI-G are essential for its "spontaneous" insertion into thylakoids and rapid assembly into the photosystem I complex. J Biol Chem 2006; 281:10548-54. [PMID: 16478728 DOI: 10.1074/jbc.m512687200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PSI-G subunit of photosystem I (PSI) is an 11-kDa membrane protein that plays an important role in electron transport between plastocyanin and PSI and is involved in the stability of the PSI complex. Within the complex, the PSI-G subunit is bound to PSI-B and is in contact with Lhca1. PSI-G has two transmembrane spans connected by a positively charged stromal loop. The loop is inaccessible to proteases, indicating a tightly bound location within the PSI complex. Here, we have studied the insertion mechanism and assembly of PSI-G. We show that the protein inserts into thylakoids by a direct or "spontaneous" pathway that does not involve the activities of any known chloroplast protein-targeting machinery. Surprisingly, the positively charged stromal loop region plays a major role in this process. Mutagenesis or deletions within this region almost invariably lead to a marked lowering of insertion efficiency, strongly indicating a critical role for the loop in the organization of the transmembrane regions prior to or during membrane insertion. Finally, we have examined the assembly of newly inserted PSI-G into the PSI complex, since very little is known of the assembly pathway for this large multimeric complex. Interestingly, we find that inserted PSI-G can be found within the full PSI complex within the import assay time frame after insertion into thylakoids, strongly suggesting that PSI-G normally associates at the end of the assembly process. This is consistent with its location on the periphery of the complex.
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Affiliation(s)
- Agnieszka Zygadlo
- Plant Biochemistry Laboratory, Department of Plant Biology, The Royal Veterinary and Agricultural University, 1870 Frederiksberg, Denmark
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Abstract
Oxygenic photosynthesis, the principal converter of sunlight into chemical energy on earth, is catalyzed by four multi-subunit membrane-protein complexes: photosystem I (PSI), photosystem II (PSII), the cytochrome b(6)f complex, and F-ATPase. PSI generates the most negative redox potential in nature and largely determines the global amount of enthalpy in living systems. PSII generates an oxidant whose redox potential is high enough to enable it to oxidize H(2)O, a substrate so abundant that it assures a practically unlimited electron source for life on earth. During the last century, the sophisticated techniques of spectroscopy, molecular genetics, and biochemistry were used to reveal the structure and function of the two photosystems. The new structures of PSI and PSII from cyanobacteria, algae, and plants has shed light not only on the architecture and mechanism of action of these intricate membrane complexes, but also on the evolutionary forces that shaped oxygenic photosynthesis.
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Affiliation(s)
- Nathan Nelson
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
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