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Yao Y, Zhang H, Guo R, Fan J, Liu S, Liao J, Huang Y, Wang Z. Physiological, Cytological, and Transcriptomic Analysis of Magnesium Protoporphyrin IX Methyltransferase Mutant Reveal Complex Genetic Regulatory Network Linking Chlorophyll Synthesis and Chloroplast Development in Rice. PLANTS (BASEL, SWITZERLAND) 2023; 12:3785. [PMID: 37960141 PMCID: PMC10649015 DOI: 10.3390/plants12213785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/20/2023] [Accepted: 11/01/2023] [Indexed: 11/15/2023]
Abstract
Functional defects in key genes for chlorophyll synthesis usually cause abnormal chloroplast development, but the genetic regulatory network for these key genes in regulating chloroplast development is still unclear. Magnesium protoporphyrin IX methyltransferase (ChlM) is a key rate-limiting enzyme in the process of chlorophyll synthesis. Physiological analysis showed that the chlorophyll and carotenoid contents were significantly decreased in the chlm mutant. Transmission electron microscopy demonstrated that the chloroplasts of the chlm mutant were not well developed, with poor, loose, and indistinct thylakoid membranes. Hormone content analysis found that jasmonic acid, salicylic acid, and auxin accumulated in the mutant. A comparative transcriptome profiling identified 1534 differentially expressed genes (DEGs) between chlm and the wild type, including 876 up-regulated genes and 658 down-regulated genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that these DEGs were highly involved in chlorophyll metabolism, chloroplast development, and photosynthesis. Protein-protein interaction network analysis found that protein translation played an essential role in the ChlM gene-regulated process. Specifically, 62 and 6 DEGs were annotated to regulate chlorophyll and carotenoid metabolism, respectively; 278 DEGs were predicted to be involved in regulating chloroplast development; 59 DEGs were found to regulate hormone regulatory pathways; 192 DEGs were annotated to regulate signal pathways; and 49 DEGs were putatively identified as transcription factors. Dozens of these genes have been well studied and reported to play essential roles in chlorophyll accumulation or chloroplast development, providing direct evidence for the reliability of the role of the identified DEGs. These findings suggest that chlorophyll synthesis and chloroplast development are actively regulated by the ChlM gene. And it is suggested that hormones, signal pathways, and transcription regulation were all involved in these regulation processes. The accuracy of transcriptome data was validated by quantitative real-time PCR (qRT-PCR) analysis. This study reveals a complex genetic regulatory network of the ChlM gene regulating chlorophyll synthesis and chloroplast development. The ChlM gene's role in retrograde signaling was discussed. Jasmonic acid, salicylic acid, or their derivatives in a certain unknown state were proposed as retrograde signaling molecules in one of the signaling pathways from the chloroplast to nucleus.
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Affiliation(s)
- Youming Yao
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P.R. China, Nanchang 330045, China; (Y.Y.); (H.Z.); (R.G.); (J.F.); (S.L.); (J.L.); (Y.H.)
- Key Laboratory of Agriculture Responding to Climate Change (Jiangxi Agricultural University), Nanchang 330045, China
| | - Hongyu Zhang
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P.R. China, Nanchang 330045, China; (Y.Y.); (H.Z.); (R.G.); (J.F.); (S.L.); (J.L.); (Y.H.)
- Key Laboratory of Agriculture Responding to Climate Change (Jiangxi Agricultural University), Nanchang 330045, China
| | - Rong Guo
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P.R. China, Nanchang 330045, China; (Y.Y.); (H.Z.); (R.G.); (J.F.); (S.L.); (J.L.); (Y.H.)
- Key Laboratory of Agriculture Responding to Climate Change (Jiangxi Agricultural University), Nanchang 330045, China
| | - Jiangmin Fan
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P.R. China, Nanchang 330045, China; (Y.Y.); (H.Z.); (R.G.); (J.F.); (S.L.); (J.L.); (Y.H.)
- Key Laboratory of Agriculture Responding to Climate Change (Jiangxi Agricultural University), Nanchang 330045, China
| | - Siyi Liu
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P.R. China, Nanchang 330045, China; (Y.Y.); (H.Z.); (R.G.); (J.F.); (S.L.); (J.L.); (Y.H.)
- Key Laboratory of Agriculture Responding to Climate Change (Jiangxi Agricultural University), Nanchang 330045, China
| | - Jianglin Liao
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P.R. China, Nanchang 330045, China; (Y.Y.); (H.Z.); (R.G.); (J.F.); (S.L.); (J.L.); (Y.H.)
- Key Laboratory of Agriculture Responding to Climate Change (Jiangxi Agricultural University), Nanchang 330045, China
| | - Yingjin Huang
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P.R. China, Nanchang 330045, China; (Y.Y.); (H.Z.); (R.G.); (J.F.); (S.L.); (J.L.); (Y.H.)
- Key Laboratory of Agriculture Responding to Climate Change (Jiangxi Agricultural University), Nanchang 330045, China
| | - Zhaohai Wang
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P.R. China, Nanchang 330045, China; (Y.Y.); (H.Z.); (R.G.); (J.F.); (S.L.); (J.L.); (Y.H.)
- Key Laboratory of Agriculture Responding to Climate Change (Jiangxi Agricultural University), Nanchang 330045, China
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Gisriel CJ, Brudvig GW. Comparison of PsbQ and Psb27 in photosystem II provides insight into their roles. PHOTOSYNTHESIS RESEARCH 2022; 152:177-191. [PMID: 35001227 PMCID: PMC9271139 DOI: 10.1007/s11120-021-00888-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 11/24/2021] [Indexed: 06/14/2023]
Abstract
Photosystem II (PSII) catalyzes the oxidation of water at its active site that harbors a high-valent inorganic Mn4CaOx cluster called the oxygen-evolving complex (OEC). Extrinsic subunits generally serve to protect the OEC from reductants and stabilize the structure, but diversity in the extrinsic subunits exists between phototrophs. Recent cryo-electron microscopy experiments have provided new molecular structures of PSII with varied extrinsic subunits. We focus on the extrinsic subunit PsbQ, that binds to the mature PSII complex, and on Psb27, an extrinsic subunit involved in PSII biogenesis. PsbQ and Psb27 share a similar binding site and have a four-helix bundle tertiary structure, suggesting they are related. Here, we use sequence alignments, structural analyses, and binding simulations to compare PsbQ and Psb27 from different organisms. We find no evidence that PsbQ and Psb27 are related despite their similar structures and binding sites. Evolutionary divergence within PsbQ homologs from different lineages is high, probably due to their interactions with other extrinsic subunits that themselves exhibit vast diversity between lineages. This may result in functional variation as exemplified by large differences in their calculated binding energies. Psb27 homologs generally exhibit less divergence, which may be due to stronger evolutionary selection for certain residues that maintain its function during PSII biogenesis and this is consistent with their more similar calculated binding energies between organisms. Previous experimental inconsistencies, low confidence binding simulations, and recent structural data suggest that Psb27 is likely to exhibit flexibility that may be an important characteristic of its activity. The analysis provides insight into the functions and evolution of PsbQ and Psb27, and an unusual example of proteins with similar tertiary structures and binding sites that probably serve different roles.
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Affiliation(s)
| | - Gary W Brudvig
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA.
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
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Biswas S, Eaton-Rye JJ. PsbX maintains efficient electron transport in Photosystem II and reduces susceptibility to high light in Synechocystis sp. PCC 6803. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148519. [PMID: 34890576 DOI: 10.1016/j.bbabio.2021.148519] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 11/15/2021] [Accepted: 11/30/2021] [Indexed: 12/13/2022]
Abstract
PsbX is a 4.1 kDa intrinsic Photosystem II (PS II) protein, found together with the low-molecular-weight proteins, PsbY and PsbJ, in proximity to cytochrome b559. The function of PsbX is not yet fully characterized but PsbX may play a role in the exchange of the secondary plastoquinone electron acceptor QB with the quinone pool in the thylakoid membrane. To study the role of PsbX, we have constructed a PsbX-lacking strain of Synechocystis sp. PCC 6803. Our studies indicate that the absence of PsbX causes sensitivity to high light and impairs electron transport within PS II. In addition to a change in the QB-binding pocket, PsbX-lacking cells exhibited sensitivity to sodium formate, suggesting altered binding of the bicarbonate ligand to the non-heme iron between the sequential plastoquinone electron acceptors QA and QB. Experiments using 35S-methionine revealed high-light-treated PsbX-lacking cells restore PS II activity during recovery under low light by an increase in the turnover of PS II-associated core proteins. These labeling experiments indicate the recovery after exposure to high light requires both selective removal and replacement of the D1 protein and de novo PS II assembly.
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Affiliation(s)
- Sandeep Biswas
- Department of Biochemistry, University of Otago, New Zealand
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Choo P, Forsman JA, Hui L, Khaing EP, Summerfield TC, Eaton-Rye JJ. The PsbJ protein is required for photosystem II activity in centers lacking the PsbO and PsbV lumenal subunits. PHOTOSYNTHESIS RESEARCH 2022; 151:103-111. [PMID: 34273062 DOI: 10.1007/s11120-021-00862-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 07/02/2021] [Indexed: 06/13/2023]
Abstract
Photosystem II (PS II) of oxygenic photosynthesis is found in the thylakoid membranes of plastids and cyanobacteria. The mature PS II complex comprises a central core of four membrane proteins that bind the majority of the redox-active cofactors. In cyanobacteria the central core is surrounded by 13 low-molecular-weight (LMW) subunits which each consist of one or two transmembrane helices. Three additional hydrophilic subunits known as PsbO, PsbU and PsbV are found associated with hydrophilic loops belonging to the core proteins protruding into the thylakoid lumen. During biogenesis the majority of the LMW subunits are known to initially associate with individual pre-assembly complexes consisting of one or more of the core proteins; however, the point at which the PsbJ LMW subunit binds to PS II is not known. The majority of models for PS II biogenesis propose that the three extrinsic proteins and PsbJ bind in the final stages of PS II assembly. We have investigated the impact of creating the double mutants ∆PsbJ:∆PsbO, ∆PsbJ:∆PsbU and ∆PsbJ:∆PsbV to investigate potential cooperation between these subunits in the final stages of biogenesis. Our results indicate that PsbJ can bind to PS II in the absence of any one of the extrinsic proteins. However, unlike their respective single mutants, the ∆PsbJ:∆PsbO and ∆PsbJ:∆PsbV strains were not photoautotrophic and were unable to support oxygen evolution suggesting a functional oxygen-evolving complex could not assemble in these strains. In contrast, the PS II centers formed in the ∆PsbJ:∆PsbU strain were capable of photoautotrophic growth and could support oxygen evolution when whole-chain electron transport was supported by the addition of bicarbonate.
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Affiliation(s)
- Priscilla Choo
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Jack A Forsman
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- Department of Botany, University of Otago, Dunedin, New Zealand
| | - Liangliang Hui
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Ei Phyo Khaing
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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Liu D, Johnson VM, Pakrasi HB. A Reversibly Induced CRISPRi System Targeting Photosystem II in the Cyanobacterium Synechocystis sp. PCC 6803. ACS Synth Biol 2020; 9:1441-1449. [PMID: 32379958 DOI: 10.1021/acssynbio.0c00106] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cyanobacterium Synechocystis sp. PCC 6803 is used as a model organism to study photosynthesis, as it can utilize glucose as the sole carbon source to support its growth under heterotrophic conditions. CRISPR interference (CRISPRi) has been widely applied to repress the transcription of genes in a targeted manner in cyanobacteria. However, a robust and reversible induced CRISPRi system has not been explored in Synechocystis 6803 to knock down and recover the expression of a targeted gene. In this study, we built a tightly controlled chimeric promoter, P rhaBAD-RSW, in which a theophylline responsive riboswitch was integrated into a rhamnose-inducible promoter system. We applied this promoter to drive the expression of ddCpf1 (DNase-dead Cpf1 nuclease) in a CRISPRi system and chose the PSII reaction center gene psbD (D2 protein) to target for repression. psbD was specifically knocked down by over 95% of its native expression, leading to severely inhibited photosystem II activity and growth of Synechocystis 6803 under photoautotrophic conditions. Significantly, removal of the inducers rhamnose and theophylline reversed repression by CRISPRi. Expression of PsbD recovered following release of repression, coupled with increased photosystem II content and activity. This reversibly induced CRISPRi system in Synechocystis 6803 represents a new strategy for study of the biogenesis of photosynthetic complexes in cyanobacteria.
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Affiliation(s)
- Deng Liu
- Department of Biology, Washington University, St. Louis, Missouri 63130, United States
| | - Virginia M Johnson
- Department of Biology, Washington University, St. Louis, Missouri 63130, United States
| | - Himadri B Pakrasi
- Department of Biology, Washington University, St. Louis, Missouri 63130, United States
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Photosynthetic protein classification using genome neighborhood-based machine learning feature. Sci Rep 2020; 10:7108. [PMID: 32346070 PMCID: PMC7189237 DOI: 10.1038/s41598-020-64053-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 04/07/2020] [Indexed: 11/08/2022] Open
Abstract
Identification of novel photosynthetic proteins is important for understanding and improving photosynthetic efficiency. Synergistically, genome neighborhood can provide additional useful information to identify photosynthetic proteins. We, therefore, expected that applying a computational approach, particularly machine learning (ML) with the genome neighborhood-based feature should facilitate the photosynthetic function assignment. Our results revealed a functional relationship between photosynthetic genes and their conserved neighboring genes observed by ‘Phylo score’, indicating their functions could be inferred from the genome neighborhood profile. Therefore, we created a new method for extracting patterns based on the genome neighborhood network (GNN) and applied them for the photosynthetic protein classification using ML algorithms. Random forest (RF) classifier using genome neighborhood-based features achieved the highest accuracy up to 87% in the classification of photosynthetic proteins and also showed better performance (Mathew’s correlation coefficient = 0.718) than other available tools including the sequence similarity search (0.447) and ML-based method (0.361). Furthermore, we demonstrated the ability of our model to identify novel photosynthetic proteins compared to the other methods. Our classifier is available at http://bicep2.kmutt.ac.th/photomod_standalone, https://bit.ly/2S0I2Ox and DockerHub: https://hub.docker.com/r/asangphukieo/photomod.
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Chen GE, Canniffe DP, Barnett SFH, Hollingshead S, Brindley AA, Vasilev C, Bryant DA, Hunter CN. Complete enzyme set for chlorophyll biosynthesis in Escherichia coli. SCIENCE ADVANCES 2018; 4:eaaq1407. [PMID: 29387799 PMCID: PMC5787379 DOI: 10.1126/sciadv.aaq1407] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/28/2017] [Indexed: 05/08/2023]
Abstract
Chlorophylls are essential cofactors for photosynthesis, which sustains global food chains and oxygen production. Billions of tons of chlorophylls are synthesized annually, yet full understanding of chlorophyll biosynthesis has been hindered by the lack of characterization of the Mg-protoporphyrin IX monomethyl ester oxidative cyclase step, which confers the distinctive green color of these pigments. We demonstrate cyclase activity using heterologously expressed enzyme. Next, we assemble a genetic module that encodes the complete chlorophyll biosynthetic pathway and show that it functions in Escherichia coli. Expression of 12 genes converts endogenous protoporphyrin IX into chlorophyll a, turning E. coli cells green. Our results delineate a minimum set of enzymes required to make chlorophyll and establish a platform for engineering photosynthesis in a heterotrophic model organism.
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Affiliation(s)
- Guangyu E. Chen
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Daniel P. Canniffe
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Samuel F. H. Barnett
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Sarah Hollingshead
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Amanda A. Brindley
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Cvetelin Vasilev
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Donald A. Bryant
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - C. Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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