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Chang Y, Tang N, Zhang M. The peptidoglycan synthase PBP interacts with PLASTID DIVISION2 to promote chloroplast division in Physcomitrium patens. THE NEW PHYTOLOGIST 2024; 241:1115-1129. [PMID: 37723553 DOI: 10.1111/nph.19268] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/19/2023] [Indexed: 09/20/2023]
Abstract
The peptidoglycan (PG) layer, a core component of the bacterial cell wall, has been retained in the Physcomitrium patens chloroplasts. The PG layer entirely encompasses the P. patens chloroplast, including the division site, but how PG biosynthesis cooperates with the constriction of two envelope membranes at the chloroplast division site remains elusive. Here, focusing on the PG synthase penicillin-binding protein (PBP), we performed cytological and molecular analyses to dissect the mechanism of chloroplast division in P. patens. We showed that PBP, acting in the final step of PG biosynthesis, is likely a chloroplast inner envelope protein that can aggregate at mid-chloroplasts during chloroplast division. Physcomitrium patens had five orthologs of PLASTID DIVISION2 (PDV2), an outer envelope component of the chloroplast division complex. Our data indicated that PpPDV2 proteins interact with PpPBP and are responsible for recruiting PpPBP to the chloroplast division site, in addition to PpDRP5B. Furthermore, we found that PBP deletion and carbenicillin application restrain constriction of the chloroplast division complex, rather than its assembly. This work provides direct molecular evidence for a link between chloroplast division of P. patens and PG biosynthesis and indicates that PG biosynthesis is required for the constriction of the chloroplast division apparatus in P. patens.
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Affiliation(s)
- Ying Chang
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing, 100048, China
| | - Ning Tang
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing, 100048, China
| | - Min Zhang
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing, 100048, China
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2
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Zheng Y, Xue C, Chen H, Jia A, Zhao L, Zhang J, Zhang L, Wang Q. Reconstitution and expression of mcy gene cluster in the model cyanobacterium Synechococcus 7942 reveals a role of MC-LR in cell division. THE NEW PHYTOLOGIST 2023; 238:1101-1114. [PMID: 36683448 DOI: 10.1111/nph.18766] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/12/2023] [Indexed: 06/17/2023]
Abstract
Cyanobacterial blooms pose a serious threat to public health due to the presence of cyanotoxins. Microcystin-LR (MC-LR) produced by Microcystis aeruginosa is the most common cyanotoxins. Due to the limitation of isolation, purification, and genetic manipulation techniques, it is difficult to study and verify in situ the biosynthetic pathways and molecular mechanisms of MC-LR. We reassembled the biosynthetic gene cluster (mcy cluster) of MC-LR in vitro by synthetic biology, designed and constructed the strong bidirectional promoter biPpsbA2 , transformed it into Synechococcus 7942, and successfully expressed MC-LR at a level of 0.006-0.018 fg cell-1 d-1 . We found the expression of MC-LR led to abnormal cell division and cellular filamentation, further using various methods proved that by irreversibly competing its GTP-binding site, MC-LR inhibits assembly of the cell division protein FtsZ. The study represents the first reconstitution and expression of the mcy cluster and the autotrophic production of MC-LR in model cyanobacterium, which lays the foundation for resolving the microcystins biosynthesis pathway. The discovered role of MC-LR in cell division reveals a mechanism of how blooming cyanobacteria gain a competitive edge over their nonblooming counterparts.
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Affiliation(s)
- Yanli Zheng
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Chunling Xue
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Hui Chen
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Anqi Jia
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Liang Zhao
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Junli Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Lixin Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
- Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng, 475004, China
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
- Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng, 475004, China
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3
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Porter KJ, Cao L, Osteryoung KW. Dynamics of the Synechococcus elongatus cytoskeletal GTPase FtsZ yields mechanistic and evolutionary insight into cyanobacterial and chloroplast FtsZs. J Biol Chem 2023; 299:102917. [PMID: 36657643 PMCID: PMC9975276 DOI: 10.1016/j.jbc.2023.102917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/17/2023] Open
Abstract
The division of cyanobacteria and their chloroplast descendants is orchestrated by filamenting temperature-sensitive Z (FtsZ), a cytoskeletal GTPase that polymerizes into protofilaments that form a "Z ring" at the division site. The Z ring has both a scaffolding function for division-complex assembly and a GTPase-dependent contractile function that drives cell or organelle constriction. A single FtsZ performs these functions in bacteria, whereas in chloroplasts, they are performed by two copolymerizing FtsZs, called AtFtsZ2 and AtFtsZ1 in Arabidopsis thaliana, which promote protofilament stability and dynamics, respectively. To probe the differences between cyanobacterial and chloroplast FtsZs, we used light scattering to characterize the in vitro protofilament dynamics of FtsZ from the cyanobacterium Synechococcus elongatus PCC 7942 (SeFtsZ) and investigate how coassembly of AtFtsZ2 or AtFtsZ1 with SeFtsZ influences overall dynamics. SeFtsZ protofilaments assembled rapidly and began disassembling before GTP depletion, whereas AtFtsZ2 protofilaments were far more stable, persisting beyond GTP depletion. Coassembled SeFtsZ-AtFtsZ2 protofilaments began disassembling before GTP depletion, similar to SeFtsZ. In contrast, AtFtsZ1 did not alter disassembly onset when coassembled with SeFtsZ, but fluorescence recovery after photobleaching analysis showed it increased the turnover of SeFtsZ subunits from SeFtsZ-AtFtsZ1 protofilaments, mirroring its effect upon coassembly with AtFtsZ2. Comparisons of our findings with previous work revealed consistent differences between cyanobacterial and chloroplast FtsZ dynamics and suggest that the scaffolding and dynamics-promoting functions were partially separated during evolution of two chloroplast FtsZs from their cyanobacterial predecessor. They also suggest that chloroplasts may have evolved a mechanism distinct from that in cyanobacteria for promoting FtsZ protofilament dynamics.
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Affiliation(s)
- Katie J Porter
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Lingyan Cao
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
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4
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TIC236 gain-of-function mutations unveil the link between plastid division and plastid protein import. Proc Natl Acad Sci U S A 2022; 119:e2123353119. [PMID: 35275795 PMCID: PMC8931380 DOI: 10.1073/pnas.2123353119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although plastid division is critical for plant development, how components of the plastid division machinery (PDM) are imported into plastids remains unexplored. A forward genetic screen to identify suppressors of a crumpled leaf (crl) mutant deficient in plastid division led us to find dominant gain-of-function (GF) mutations in TIC236, which significantly increases the import of PDM components and completely rescues crl phenotypes. The defective plastid division phenotypes in crl and tic236-knockdown mutants and CRL-TIC236 association in a functional complex indicate that the CRL-TIC236 module is vital for plastid division. Hence, we report the first GF translocon mutants and unveil CRL as a novel functional partner of TIC236 for PDM import. TIC236 is an essential component of the translocon for protein import into chloroplasts, as evidenced by the embryonic lethality of the knockout mutant. Here, we unveil a TIC236-allied component, the chloroplast outer membrane protein CRUMPLED LEAF (CRL), absence of which impairs plastid division and induces autoimmune responses in Arabidopsis thaliana. A forward genetic screen exploring CRL function found multiple dominant TIC236 gain-of-function (tic236-gf) mutations that abolished crl-induced phenotypes. Moreover, CRL associates with TIC236, and a tic236-knockdown mutant exhibited multiple lesions similar to the crl mutant, supporting their shared functionality. Consistent with the defective plastid division phenotype of crl, CRL interacts with the transit peptides of proteins essential in plastid division, with tic236-gf mutations reinforcing their import via increased TIC236 stability. Ensuing reverse genetic analyses further revealed genetic interaction between CRL and SP1, a RING-type ubiquitin E3 ligase, as well as with the plastid protease FTSH11, which function in TOC and TIC protein turnover, respectively. Loss of either SP1 or FTSH11 rescued crl mutant phenotypes to varying degrees due to increased translocon levels. Collectively, our data shed light on the links between plastid protein import, plastid division, and plant stress responses.
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5
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Cackett L, Luginbuehl LH, Schreier TB, Lopez-Juez E, Hibberd JM. Chloroplast development in green plant tissues: the interplay between light, hormone, and transcriptional regulation. THE NEW PHYTOLOGIST 2022; 233:2000-2016. [PMID: 34729790 DOI: 10.1111/nph.17839] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/09/2021] [Indexed: 05/20/2023]
Abstract
Chloroplasts are best known for their role in photosynthesis, but they also allow nitrogen and sulphur assimilation, amino acid, fatty acid, nucleotide and hormone synthesis. How chloroplasts develop is therefore relevant to these diverse and fundamental biological processes, but also to attempts at their rational redesign. Light is strictly required for chloroplast formation in all angiosperms and directly regulates the expression of hundreds of chloroplast-related genes. Light also modulates the levels of several hormones including brassinosteriods, cytokinins, auxins and gibberellins, which themselves control chloroplast development particularly during early stages of plant development. Transcription factors such as GOLDENLIKE1&2 (GLK1&2), GATA NITRATE-INDUCIBLE CARBON METABOLISM-INVOLVED (GNC) and CYTOKININ-RESPONSIVE GATA FACTOR 1 (CGA1) act downstream of both light and phytohormone signalling to regulate chloroplast development. Thus, in green tissues transcription factors, light signalling and hormone signalling form a complex network regulating the transcription of chloroplast- and photosynthesis-related genes to control the development and number of chloroplasts per cell. We use this conceptual framework to identify points of regulation that could be harnessed to modulate chloroplast abundance and increase photosynthetic efficiency of crops, and to highlight future avenues to overcome gaps in current knowledge.
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Affiliation(s)
- Lee Cackett
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Leonie H Luginbuehl
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Tina B Schreier
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Enrique Lopez-Juez
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
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6
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Liu X, An J, Wang L, Sun Q, An C, Wu B, Hong C, Wang X, Dong S, Guo J, Feng Y, Gao H. A novel amphiphilic motif at the C-terminus of FtsZ1 facilitates chloroplast division. THE PLANT CELL 2022; 34:419-432. [PMID: 34755875 PMCID: PMC8773991 DOI: 10.1093/plcell/koab272] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/29/2021] [Indexed: 06/11/2023]
Abstract
In bacteria and chloroplasts, the GTPase filamentous temperature-sensitive Z (FtsZ) is essential for division and polymerizes to form rings that mark the division site. Plants contain two FtsZ subfamilies (FtsZ1 and FtsZ2) with different assembly dynamics. FtsZ1 lacks the C-terminal domain of a typical FtsZ protein. Here, we show that the conserved short motif FtsZ1Carboxyl-terminus (Z1C) (consisting of the amino acids RRLFF) with weak membrane-binding activity is present at the C-terminus of FtsZ1 in angiosperms. For a polymer-forming protein such as FtsZ, this activity is strong enough for membrane tethering. Arabidopsis thaliana plants with mutated Z1C motifs contained heterogeneously sized chloroplasts and parallel FtsZ rings or long FtsZ filaments, suggesting that the Z1C motif plays an important role in regulating FtsZ ring dynamics. Our findings uncover a type of amphiphilic beta-strand motif with weak membrane-binding activity and point to the importance of this motif for the dynamic regulation of protein complex formation.
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Affiliation(s)
- Xiaomin Liu
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
| | - Jinjie An
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Lulu Wang
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Qingqing Sun
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Chuanjing An
- Department of Chemical Biology, State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Bibo Wu
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Conghao Hong
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Xiaoya Wang
- Department of Chemical Biology, State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Suwei Dong
- Department of Chemical Biology, State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Junhua Guo
- College of Life Science and Technology, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yue Feng
- College of Life Science and Technology, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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7
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Porter KJ, Cao L, Chen Y, TerBush AD, Chen C, Erickson HP, Osteryoung KW. The Arabidopsis thaliana chloroplast division protein FtsZ1 counterbalances FtsZ2 filament stability in vitro. J Biol Chem 2021; 296:100627. [PMID: 33812992 PMCID: PMC8142252 DOI: 10.1016/j.jbc.2021.100627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 11/18/2022] Open
Abstract
Bacterial cell and chloroplast division are driven by a contractile “Z ring” composed of the tubulin-like cytoskeletal GTPase FtsZ. Unlike bacterial Z rings, which consist of a single FtsZ, the chloroplast Z ring in plants is composed of two FtsZ proteins, FtsZ1 and FtsZ2. Both are required for chloroplast division in vivo, but their biochemical relationship is poorly understood. We used GTPase assays, light scattering, transmission electron microscopy, and sedimentation assays to investigate the assembly behavior of purified Arabidopsis thaliana (At) FtsZ1 and AtFtsZ2 both individually and together. Both proteins exhibited GTPase activity. AtFtsZ2 assembled relatively quickly, forming protofilament bundles that were exceptionally stable, as indicated by their sustained assembly and slow disassembly. AtFtsZ1 did not form detectable protofilaments on its own. When mixed with AtFtsZ2, AtFtsZ1 reduced the extent and rate of AtFtsZ2 assembly, consistent with its previously demonstrated ability to promote protofilament subunit turnover in living cells. Mixing the two FtsZ proteins did not increase the overall GTPase activity, indicating that the effect of AtFtsZ1 on AtFtsZ2 assembly was not due to a stimulation of GTPase activity. However, the GTPase activity of AtFtsZ1 was required to reduce AtFtsZ2 assembly. Truncated forms of AtFtsZ1 and AtFtsZ2 consisting of only their conserved core regions largely recapitulated the behaviors of the full-length proteins. Our in vitro findings provide evidence that FtsZ1 counterbalances the stability of FtsZ2 filaments in the regulation of chloroplast Z-ring dynamics and suggest that restraining FtsZ2 self-assembly is a critical function of FtsZ1 in chloroplasts.
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Affiliation(s)
- Katie J Porter
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Lingyan Cao
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Yaodong Chen
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Allan D TerBush
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Cheng Chen
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Harold P Erickson
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA
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8
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Sun T, Yuan H, Chen C, Kadirjan-Kalbach DK, Mazourek M, Osteryoung KW, Li L. OR His, a Natural Variant of OR, Specifically Interacts with Plastid Division Factor ARC3 to Regulate Chromoplast Number and Carotenoid Accumulation. MOLECULAR PLANT 2020; 13:864-878. [PMID: 32222485 DOI: 10.1016/j.molp.2020.03.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 05/19/2023]
Abstract
Chromoplasts are colored plastids that synthesize and store massive amounts of carotenoids. Chromoplast number and size define the sink strength for carotenoid accumulation in plants. However, nothing is known about the mechanisms controlling chromoplast number. Previously, a natural allele of Orange (OR), ORHis, was found to promote carotenoid accumulation by activating chromoplast differentiation and increasing carotenoid biosynthesis, but cells in orange tissues in melon fruit and cauliflower OR mutant have only one or two enlarged chromoplasts. In this study, we investigated an ORHis variant of Arabidopsis OR, genetically mimicking the melon ORHis allele, and found that it also constrains chromoplast number in Arabidopsis calli. Both in vitro and in vivo experiments demonstrate that ORHis specifically interacts with the Membrane Occupation and Recognition Nexus domain of ACCUMULATION AND REPLICATION OF CHLOROPLASTS 3 (ARC3), a crucial regulator of chloroplast division. We further showed that ORHis interferes with the interaction between ARC3 and PARALOG OF ARC6 (PARC6), another key regulator of chloroplast division, suggesting a role of ORHis in competing with PARC6 for binding to ARC3 to restrict chromoplast number. Overexpression or knockout of ARC3 in Arabidopsis ORHis plants significantly alters total carotenoid levels. Moreover, overexpression of the plastid division factor PLASTID DIVISION 1 greatly enhances carotenoid accumulation. These division factors likely alter carotenoid levels via their influence on chromoplast number and/or size. Taken together, our findings provide novel mechanistic insights into the machinery controlling chromoplast number and highlight a potential new strategy for enhancing carotenoid accumulation and nutritional value in food crops.
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Affiliation(s)
- Tianhu Sun
- Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY 14853, USA; Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
| | - Hui Yuan
- Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY 14853, USA; Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
| | - Cheng Chen
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | | | - Michael Mazourek
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
| | | | - Li Li
- Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY 14853, USA; Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA.
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9
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Kadirjan-Kalbach DK, Turmo A, Wang J, Smith BC, Chen C, Porter KJ, Childs KL, DellaPenna D, Osteryoung KW. Allelic Variation in the Chloroplast Division Gene FtsZ2-2 Leads to Natural Variation in Chloroplast Size. PLANT PHYSIOLOGY 2019; 181:1059-1074. [PMID: 31488573 PMCID: PMC6836828 DOI: 10.1104/pp.19.00841] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
Chloroplast size varies considerably in nature, but the underlying mechanisms are unknown. By exploiting a near-isogenic line population derived from a cross between the Arabidopsis (Arabidopsis thaliana) accessions Cape Verde Islands (Cvi-1), which has larger chloroplasts, and Landsberg erecta (Ler-0), with smaller chloroplasts, we determined that the large-chloroplast phenotype in Cvi-1 is associated with allelic variation in the gene encoding the chloroplast-division protein FtsZ2-2, a tubulin-related cytoskeletal component of the contractile FtsZ ring inside chloroplasts. Sequencing revealed that the Cvi-1 FtsZ2-2 allele encodes a C-terminally truncated protein lacking a region required for FtsZ2-2 interaction with inner-envelope proteins, and functional complementation experiments in a Columbia-0 ftsZ2-2 null mutant confirmed this allele as causal for the increased chloroplast size in Cvi-1. Comparison of FtsZ2-2 coding sequences in the 1001 Genomes database showed that the Cvi-1 allele is rare and identified additional rare loss-of-function alleles, including a natural null allele, in three other accessions, all of which had enlarged-chloroplast phenotypes. The ratio of nonsynonymous to synonymous substitutions was higher among the FtsZ2-2 genes than among the two other FtsZ family members in Arabidopsis, FtsZ2-1, a close paralog of FtsZ2-2, and the functionally distinct FtsZ1-1, indicating more relaxed constraint on the FtsZ2-2 coding sequence than on those of FtsZ2-1 or FtsZ1-1 Our results establish that allelic variation in FtsZ2-2 contributes to natural variation in chloroplast size in Arabidopsis, and they also demonstrate that natural variation in Arabidopsis can be used to decipher the genetic basis of differences in fundamental cell biological traits, such as organelle size.
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Affiliation(s)
| | - Aiko Turmo
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Jie Wang
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Brandon C Smith
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Cheng Chen
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Katie J Porter
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Kevin L Childs
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Dean DellaPenna
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
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10
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Wang N, Bian L, Ma X, Meng Y, Chen CS, Rahman MU, Zhang T, Li Z, Wang P, Chen Y. Assembly properties of the bacterial tubulin homolog FtsZ from the cyanobacterium Synechocystis sp. PCC 6803. J Biol Chem 2019; 294:16309-16319. [PMID: 31519752 DOI: 10.1074/jbc.ra119.009621] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/10/2019] [Indexed: 11/06/2022] Open
Abstract
The tubulin homolog FtsZ is the major cytoskeletal protein in the bacterial cell division machinery, conserved in almost all bacteria, archaea, and chloroplasts. Bacterial FtsZ assembles spontaneously into single protofilaments, sheets, and bundles in vitro, and it also accumulates at the site of division early during cell division, where it forms a dynamic protein complex, the contractile ring or Z-ring. The biochemical properties of FtsZ proteins from many bacteria have been studied, but comparable insights into FtsZs from cyanobacteria are limited. Here, using EM and light-scattering assays, we studied the biochemical and assembly properties of SyFtsZ, the FtsZ protein from the cyanobacterial strain Synechocystis sp. PCC 6803. SyFtsZ had a slow GTPase activity of ∼0.4 GTP/FtsZ molecule/min and assembled into thick, straight protofilament bundles and curved bundles, designated toroids. The assembly of SyFtsZ in the presence of GTP occurred in two stages. The first stage consisted of the assembly of single-stranded straight protofilaments and opened circles; in the second stage, the protofilaments associated into straight protofilament bundles and toroids. In addition to these assemblies, we also observed highly curved oligomers and minirings after GTP hydrolysis or in the presence of excess GDP. The three types of protofilaments of SyFtsZ observed here provide support for the hypothesis that a constriction force due to curved protofilaments bends the membrane. In summary, our findings indicate that, unlike other bacterial FtsZ, SyFtsZ assembles into thick protofilament bundles. This bundling is similar to that of chloroplast FtsZ, consistent with its origin in cyanobacteria.
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Affiliation(s)
- Na Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
| | - Li Bian
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
| | - Xueqin Ma
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
| | - Yufeng Meng
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
| | - Cyndi S Chen
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Mujeeb Ur Rahman
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
| | - Tingting Zhang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
| | - Zhe Li
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
| | - Ping Wang
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Yaodong Chen
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
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11
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Yoshida Y, Mogi Y. How do plastids and mitochondria divide? Microscopy (Oxf) 2019; 68:45-56. [PMID: 30476140 DOI: 10.1093/jmicro/dfy132] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/16/2018] [Indexed: 12/30/2022] Open
Abstract
Plastids and mitochondria are thought to have originated from free-living cyanobacterial and alpha-proteobacterial ancestors, respectively, via endosymbiosis. Their evolutionary origins dictate that these organelles do not multiply de novo but through the division of pre-existing plastids and mitochondria. Over the past three decades, studies have shown that plastid and mitochondrial division are performed by contractile ring-shaped structures, broadly termed the plastid and mitochondrial-division machineries. Interestingly, the division machineries are hybrid forms of the bacterial cell division system and eukaryotic membrane fission system. The structure and function of the plastid and mitochondrial-division machineries are similar to each other, implying that the division machineries evolved in parallel since their establishment in primitive eukaryotes. Compared with our knowledge of their structures, our understanding of the mechanical details of how these division machineries function is still quite limited. Here, we review and compare the structural frameworks of the plastid and mitochondrial-division machineries in both lower and higher eukaryotes. Then, we highlight fundamental issues that need to be resolved to reveal the underlying mechanisms of plastid and mitochondrial division. Finally, we highlight related studies that point to an exciting future for the field.
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Affiliation(s)
- Yamato Yoshida
- Department of Science, College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, Japan
| | - Yuko Mogi
- Department of Science, College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, Japan
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12
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Chen C, Cao L, Yang Y, Porter KJ, Osteryoung KW. ARC3 Activation by PARC6 Promotes FtsZ-Ring Remodeling at the Chloroplast Division Site. THE PLANT CELL 2019; 31:862-885. [PMID: 30824505 PMCID: PMC6501610 DOI: 10.1105/tpc.18.00948] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/04/2019] [Accepted: 02/28/2019] [Indexed: 05/29/2023]
Abstract
Chloroplast division is initiated by assembly of the stromal Z ring, composed of cytoskeletal Filamenting temperature-sensitive Z (FtsZ) proteins. Midplastid Z-ring positioning is governed by the chloroplast Min (Minicell) system, which inhibits Z-ring assembly everywhere except the division site. The central Min-system player is the FtsZ-assembly inhibitor ACCUMULATION AND REPLICATION OF CHLOROPLASTS3 (ARC3). Here, we report Arabidopsis (Arabidopsis thaliana) chloroplasts contain two pools of ARC3: one distributed throughout the stroma, which presumably fully inhibits Z-ring assembly at nondivision sites, and the other localized to a midplastid ring-like structure. We show that ARC3 is recruited to the middle of the plastid by the inner envelope membrane protein PARALOG OF ARC6 (PARC6). ARC3 bears a C-terminal Membrane Occupation and Recognition Nexus (MORN) domain; previous yeast two-hybrid experiments with full-length and MORN-truncated ARC3 showed the MORN domain mediates ARC3-PARC6 interaction but prevents ARC3-FtsZ interaction. Using yeast three-hybrid experiments, we demonstrate that the MORN-dependent ARC3-PARC6 interaction enables full-length ARC3 to bind FtsZ. The resulting PARC6/ARC3/FtsZ complex enhances the dynamics of Z rings reconstituted in a heterologous system. Our findings lead to a model whereby activation of midplastid-localized ARC3 by PARC6 facilitates Z-ring remodeling during chloroplast division by promoting Z-ring dynamics and reveal a novel function for MORN domains in regulating protein-protein interactions.
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13
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Howell M, Aliashkevich A, Sundararajan K, Daniel JJ, Lariviere PJ, Goley ED, Cava F, Brown PJB. Agrobacterium tumefaciens divisome proteins regulate the transition from polar growth to cell division. Mol Microbiol 2019; 111:1074-1092. [PMID: 30693575 DOI: 10.1111/mmi.14212] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2019] [Indexed: 01/06/2023]
Abstract
The mechanisms that restrict peptidoglycan biosynthesis to the pole during elongation and re-direct peptidoglycan biosynthesis to mid-cell during cell division in polar-growing Alphaproteobacteria are largely unknown. Here, we explore the role of early division proteins of Agrobacterium tumefaciens including three FtsZ homologs, FtsA and FtsW in the transition from polar growth to mid-cell growth and ultimately cell division. Although two of the three FtsZ homologs localize to mid-cell, exhibit GTPase activity and form co-polymers, only one, FtsZAT , is required for cell division. We find that FtsZAT is required not only for constriction and cell separation, but also for initiation of peptidoglycan synthesis at mid-cell and cessation of polar peptidoglycan biosynthesis. Depletion of FtsZAT in A. tumefaciens causes a striking phenotype: cells are extensively branched and accumulate growth active poles through tip splitting events. When cell division is blocked at a later stage by depletion of FtsA or FtsW, polar growth is terminated and ectopic growth poles emerge from mid-cell. Overall, this work suggests that A. tumefaciens FtsZ makes distinct contributions to the regulation of polar growth and cell division.
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Affiliation(s)
- Matthew Howell
- Division of Biological Sciences, University of Missouri, Columbia, MO, 65203, USA
| | - Alena Aliashkevich
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Kousik Sundararajan
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Jeremy J Daniel
- Division of Biological Sciences, University of Missouri, Columbia, MO, 65203, USA
| | - Patrick J Lariviere
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Erin D Goley
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Felipe Cava
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Pamela J B Brown
- Division of Biological Sciences, University of Missouri, Columbia, MO, 65203, USA
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14
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Chen L, Sun B, Gao W, Zhang QY, Yuan H, Zhang M. MCD1 Associates with FtsZ Filaments via the Membrane-Tethering Protein ARC6 to Guide Chloroplast Division. THE PLANT CELL 2018; 30:1807-1823. [PMID: 29967285 PMCID: PMC6139695 DOI: 10.1105/tpc.18.00189] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/08/2018] [Accepted: 06/23/2018] [Indexed: 05/29/2023]
Abstract
Chloroplasts replicate by binary fission, a process driven by ring-like dynamic division machinery at mid-chloroplast. In Arabidopsis thaliana, the first molecular assembly of this machinery, the Z-ring, forms via the association of FtsZ1 and FtsZ2 heteropolymers with the inner envelope membrane through the membrane-tethering protein ACCUMULATION AND REPLICATION OF CHLOROPLASTS6 (ARC6). Spatial control of Z-ring assembly ensures the correct placement of the division machinery and, therefore, symmetric chloroplast division. The plant-specific protein MULTIPLE CHLOROPLAST DIVISION SITE1 (MCD1) plays a role in Z-ring positioning and chloroplast division site placement, but its mechanism of action is unknown. Here, we provide evidence that MCD1 is a bitopic inner membrane protein whose C terminus faces the chloroplast stroma. Interaction analysis showed that MCD1 and ARC6 directly interact in the stroma and that MCD1 binds to FtsZ2 in an ARC6-dependent manner. These results are consistent with the in vivo observation that ARC6 influences the localization of MCD1 to membrane-tethered FtsZ filaments. Additionally, we found that MCD1 is required for the regulation of Z-ring positioning by ARC3 and MinE1, two components of the chloroplast Min (minicell) system, which negatively regulates Z-ring placement. Together, our findings indicate that MCD1 is part of the chloroplast Min system that recognizes membrane-tethered FtsZ filaments during chloroplast division-ring positioning.
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Affiliation(s)
- Li Chen
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Bing Sun
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Wei Gao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Qi-Yang Zhang
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Huan Yuan
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Min Zhang
- College of Life Sciences, Capital Normal University, Beijing 100048, China
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15
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Swid N, Nevo R, Kiss V, Kapon R, Dagan S, Snir O, Adam Z, Falconet D, Reich Z, Charuvi D. Differential impacts of FtsZ proteins on plastid division in the shoot apex of Arabidopsis. Dev Biol 2018; 441:83-94. [PMID: 29920253 DOI: 10.1016/j.ydbio.2018.06.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/11/2018] [Accepted: 06/14/2018] [Indexed: 11/26/2022]
Abstract
FtsZ proteins of the FtsZ1 and FtsZ2 families play important roles in the initiation and progression of plastid division in plants and green algae. Arabidopsis possesses a single FTSZ1 member and two FTSZ2 members, FTSZ2-1 and FTSZ2-2. The contribution of these to chloroplast division and partitioning has been mostly investigated in leaf mesophyll tissues. Here, we assessed the involvement of the three FtsZs in plastid division at earlier stages of chloroplast differentiation. To this end, we studied the effect of the absence of specific FtsZ proteins on plastids in the vegetative shoot apex, where the proplastid-to-chloroplast transition takes place. We found that the relative contribution of the two major leaf FtsZ isoforms, FtsZ1 and FtsZ2-1, to the division process varies with cell lineage and position within the shoot apex. While FtsZ2-1 dominates division in the L1 and L3 layers of the shoot apical meristem (SAM), in the L2 layer, FtsZ1 and FtsZ2-1 contribute equally toward the process. Depletion of the third isoform, FtsZ2-2, generally resulted in stronger effects in the shoot apex than those observed in mature leaves. The implications of these findings, along with additional observations made in this work, to our understanding of the mechanisms and regulation of plastid proliferation in the shoot apex are discussed.
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Affiliation(s)
- Neora Swid
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 7610001, Israel; Institute of Plant Sciences, Agricultural Research Organization - Volcani Center, Rishon LeZion 7505101, Israel; Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Reinat Nevo
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Vladimir Kiss
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ruti Kapon
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shlomi Dagan
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Orli Snir
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Zach Adam
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Denis Falconet
- Laboratoire de Physiologie Cellulaire et Végétale, LPCV-BIG, UMR 5168 CNRS-CEA-INRA-Université Grenoble Alpes, 38000 Grenoble, France
| | - Ziv Reich
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dana Charuvi
- Institute of Plant Sciences, Agricultural Research Organization - Volcani Center, Rishon LeZion 7505101, Israel.
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16
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Sung MW, Shaik R, TerBush AD, Osteryoung KW, Vitha S, Holzenburg A. The chloroplast division protein ARC6 acts to inhibit disassembly of GDP-bound FtsZ2. J Biol Chem 2018; 293:10692-10706. [PMID: 29769312 DOI: 10.1074/jbc.ra117.000999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 04/14/2018] [Indexed: 01/12/2023] Open
Abstract
Chloroplasts host photosynthesis and fulfill other metabolic functions that are essential to plant life. They have to divide by binary fission to maintain their numbers throughout cycles of cell division. Chloroplast division is achieved by a complex ring-shaped division machinery located on both the inner (stromal) and the outer (cytosolic) side of the chloroplast envelope. The inner division ring (termed the Z ring) is formed by the assembly of tubulin-like FtsZ1 and FtsZ2 proteins. ARC6 is a key chloroplast division protein that interacts with the Z ring. ARC6 spans the inner envelope membrane, is known to stabilize or maintain the Z ring, and anchors the Z ring to the inner membrane through interaction with FtsZ2. The underlying mechanism of Z ring stabilization is not well-understood. Here, biochemical and structural characterization of ARC6 was conducted using light scattering, sedimentation, and light and transmission EM. The recombinant protein was purified as a dimer. The results indicated that a truncated form of ARC6 (tARC6), representing the stromal portion of ARC6, affects FtsZ2 assembly without forming higher-order structures and exerts its effect via FtsZ2 dynamics. tARC6 prevented GDP-induced FtsZ2 disassembly and caused a significant net increase in FtsZ2 assembly when GDP was present. Single particle analysis and 3D reconstruction were performed to elucidate the structural basis of ARC6 activity. Together, the data reveal that a dimeric form of tARC6 binds to FtsZ2 filaments and does not increase FtsZ polymerization rates but rather inhibits GDP-associated FtsZ2 disassembly.
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Affiliation(s)
- Min Woo Sung
- From the Department of Biology, Texas A&M University, College Station, Texas 77843
| | - Rahamthulla Shaik
- From the Department of Biology, Texas A&M University, College Station, Texas 77843
| | - Allan D TerBush
- the Biochemistry and Molecular Biology Graduate Program and.,Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | | | - Stanislav Vitha
- the Microscopy and Imaging Center, Texas A&M University, College Station, Texas 77843, and
| | - Andreas Holzenburg
- From the Department of Biology, Texas A&M University, College Station, Texas 77843.,the Microscopy and Imaging Center, Texas A&M University, College Station, Texas 77843, and.,the Department of Biomedical Sciences, School of Medicine, University of Texas Rio Grande Valley, Brownsville-Edinburg-Harlingen, Texas 78550
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17
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Irieda H, Shiomi D. Bacterial Heterologous Expression System for Reconstitution of Chloroplast Inner Division Ring and Evaluation of Its Contributors. Int J Mol Sci 2018; 19:ijms19020544. [PMID: 29439474 PMCID: PMC5855766 DOI: 10.3390/ijms19020544] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 02/07/2018] [Accepted: 02/08/2018] [Indexed: 12/23/2022] Open
Abstract
Plant chloroplasts originate from the symbiotic relationship between ancient free-living cyanobacteria and ancestral eukaryotic cells. Since the discovery of the bacterial derivative FtsZ gene—which encodes a tubulin homolog responsible for the formation of the chloroplast inner division ring (Z ring)—in the Arabidopsis genome in 1995, many components of the chloroplast division machinery were successively identified. The knowledge of these components continues to expand; however, the mode of action of the chloroplast dividing system remains unknown (compared to bacterial cell division), owing to the complexities faced in in planta analyses. To date, yeast and bacterial heterologous expression systems have been developed for the reconstitution of Z ring-like structures formed by chloroplast FtsZ. In this review, we especially focus on recent progress of our bacterial system using the model bacterium Escherichia coli to dissect and understand the chloroplast division machinery—an evolutionary hybrid structure composed of both bacterial (inner) and host-derived (outer) components.
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Affiliation(s)
- Hiroki Irieda
- Academic Assembly, Institute of Agriculture, Shinshu University, Nagano 399-4598, Japan.
| | - Daisuke Shiomi
- Department of Life Science, College of Science, Rikkyo University, Tokyo 171-8501, Japan.
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18
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Chloroplast division protein ARC3 acts on FtsZ2 by preventing filament bundling and enhancing GTPase activity. Biochem J 2018; 475:99-115. [PMID: 29138260 DOI: 10.1042/bcj20170697] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 01/28/2023]
Abstract
Chloroplasts evolved from cyanobacterial endosymbiotic ancestors and their division is a complex process initiated by the assembly of cytoskeletal FtsZ (Filamentous temperature sensitive Z) proteins into a ring structure at the division site (Z-ring). The cyanobacterial Z-ring positioning system (MinCDE proteins) is also conserved in chloroplasts, except that MinC was lost and replaced by the eukaryotic ARC3 (accumulation and replication of chloroplasts). Both MinC and ARC3 act as negative regulators of FtsZ assembly, but ARC3 bears little sequence similarity with MinC. Here, light scattering assays, co-sedimentation, GTPase assay and transmission electron microscopy in conjunction with single-particle analysis have been used to elucidate the structure of ARC3 and its effect on its main target in chloroplast division, FtsZ2. Analysis of FtsZ2 in vitro assembly reactions in the presence and absence of GMPCPP showed that ARC3 promotes FtsZ2 debundling and disassembly of existing filaments in a concentration-dependent manner and requires GTP hydrolysis. Three-dimensional reconstruction of ARC3 revealed an almost circular molecule in which the FtsZ-binding N-terminus and the C-terminal PARC6 (paralog of ARC6)-binding MORN (Membrane Occupation and Recognition Nexus) domain are in close proximity and suggest a model for PARC6-enabled binding of ARC3 to FtsZ2. The latter is corroborated by in vivo data.
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19
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TerBush AD, MacCready JS, Chen C, Ducat DC, Osteryoung KW. Conserved Dynamics of Chloroplast Cytoskeletal FtsZ Proteins Across Photosynthetic Lineages. PLANT PHYSIOLOGY 2018; 176:295-306. [PMID: 28814573 PMCID: PMC5761766 DOI: 10.1104/pp.17.00558] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/13/2017] [Indexed: 05/08/2023]
Abstract
The cytoskeletal Filamenting temperature-sensitive Z (FtsZ) ring is critical for cell division in bacteria and chloroplast division in photosynthetic eukaryotes. While bacterial FtsZ rings are composed of a single FtsZ, except in the basal glaucophytes, chloroplast division involves two heteropolymer-forming FtsZ isoforms: FtsZ1 and FtsZ2 in the green lineage and FtsZA and FtsZB in red algae. FtsZ1 and FtsZB probably arose by duplication of the more ancestral FtsZ2 and FtsZA, respectively. We expressed fluorescent fusions of FtsZ from diverse photosynthetic organisms in a heterologous system to compare their intrinsic assembly and dynamic properties. FtsZ2 and FtsZA filaments were morphologically distinct from FtsZ1 and FtsZB filaments. When coexpressed, FtsZ pairs from plants and algae colocalized, consistent with heteropolymerization. Fluorescence recovery after photobleaching experiments demonstrated that subunit exchange was greater from FtsZ1 and FtsZB filaments than from FtsZ2 and FtsZA filaments and that FtsZ1 and FtsZB increased turnover of FtsZ2 and FtsZA, respectively, from heteropolymers. GTPase activity was essential only for turnover of FtsZ2 and FtsZA filaments. Cyanobacterial and glaucophyte FtsZ properties mostly resembled those of FtsZ2 and FtsZA, though the glaucophyte protein exhibited some hybrid features. Our results demonstrate that the more ancestral FtsZ2 and FtsZA have retained functional attributes of their common FtsZ ancestor, while eukaryotic-specific FtsZ1 and FtsZB acquired new but similar dynamic properties, possibly through convergent evolution. Our findings suggest that the evolution of a second FtsZ that could copolymerize with the more ancestral form to enhance FtsZ-ring dynamics may have been essential for plastid evolution in the green and red photosynthetic lineages.
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Affiliation(s)
- Allan D TerBush
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Biochemistry and Molecular Biology Graduate Program, Michigan State University, East Lansing, Michigan 48824
| | - Joshua S MacCready
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Microbiology and Molecular Genetics Graduate Program, Michigan State University, East Lansing, Michigan 48824
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
| | - Cheng Chen
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Daniel C Ducat
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
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20
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Chen C, MacCready JS, Ducat DC, Osteryoung KW. The Molecular Machinery of Chloroplast Division. PLANT PHYSIOLOGY 2018; 176:138-151. [PMID: 29079653 PMCID: PMC5761817 DOI: 10.1104/pp.17.01272] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 11/09/2017] [Indexed: 05/17/2023]
Abstract
Recent studies advance understanding of the mechanisms, spatial control, and regulation of chloroplast division, but many questions remain.
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Affiliation(s)
- Cheng Chen
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Joshua S MacCready
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Daniel C Ducat
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
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21
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Geng MT, Min Y, Yao Y, Chen X, Fan J, Yuan S, Wang L, Sun C, Zhang F, Shang L, Wang YL, Li RM, Fu SP, Duan RJ, Liu J, Hu XW, Guo JC. Isolation and Characterization of Ftsz Genes in Cassava. Genes (Basel) 2017; 8:genes8120391. [PMID: 29244730 PMCID: PMC5748709 DOI: 10.3390/genes8120391] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 12/01/2017] [Accepted: 12/12/2017] [Indexed: 11/16/2022] Open
Abstract
The filamenting temperature-sensitive Z proteins (FtsZs) play an important role in plastid division. In this study, three FtsZ genes were isolated from the cassava genome, and named MeFtsZ1, MeFtsZ2-1, and MeFtsZ2-2, respectively. Based on phylogeny, the MeFtsZs were classified into two groups (FtsZ1 and FtsZ2). MeFtsZ1 with a putative signal peptide at N-terminal, has six exons, and is classed to FtsZ1 clade. MeFtsZ2-1 and MeFtsZ2-2 without a putative signal peptide, have seven exons, and are classed to FtsZ2 clade. Subcellular localization found that all the three MeFtsZs could locate in chloroplasts and form a ring in chloroplastids. Structure analysis found that all MeFtsZ proteins contain a conserved guanosine triphosphatase (GTPase) domain in favor of generate contractile force for cassava plastid division. The expression profiles of MeFtsZ genes by quantitative reverse transcription-PCR (qRT-PCR) analysis in photosynthetic and non-photosynthetic tissues found that all of the MeFtsZ genes had higher expression levels in photosynthetic tissues, especially in younger leaves, and lower expression levels in the non-photosynthetic tissues. During cassava storage root development, the expressions of MeFtsZ2-1 and MeFtsZ2-2 were comparatively higher than MeFtsZ1. The transformed Arabidopsis of MeFtsZ2-1 and MeFtsZ2-2 contained abnormally shape, fewer number, and larger volume chloroplasts. Phytohormones were involved in regulating the expressions of MeFtsZ genes. Therefore, we deduced that all of the MeFtsZs play an important role in chloroplast division, and that MeFtsZ2 (2-1, 2-2) might be involved in amyloplast division and regulated by phytohormones during cassava storage root development.
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Affiliation(s)
- Meng-Ting Geng
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Yi Min
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Yuan Yao
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
| | - Xia Chen
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Jie Fan
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Shuai Yuan
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Lei Wang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Chong Sun
- College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
| | - Fan Zhang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Lu Shang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Yun-Lin Wang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Rui-Mei Li
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
| | - Shao-Ping Fu
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
| | - Rui-Jun Duan
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
| | - Jiao Liu
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
| | - Xin-Wen Hu
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
| | - Jian-Chun Guo
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
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22
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Abstract
FtsZ, a homolog of tubulin, is found in almost all bacteria and archaea where it has a primary role in cytokinesis. Evidence for structural homology between FtsZ and tubulin came from their crystal structures and identification of the GTP box. Tubulin and FtsZ constitute a distinct family of GTPases and show striking similarities in many of their polymerization properties. The differences between them, more so, the complexities of microtubule dynamic behavior in comparison to that of FtsZ, indicate that the evolution to tubulin is attributable to the incorporation of the complex functionalities in higher organisms. FtsZ and microtubules function as polymers in cell division but their roles differ in the division process. The structural and partial functional homology has made the study of their dynamic properties more interesting. In this review, we focus on the application of the information derived from studies on FtsZ dynamics to study microtubule dynamics and vice versa. The structural and functional aspects that led to the establishment of the homology between the two proteins are explained to emphasize the network of FtsZ and microtubule studies and how they are connected.
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Affiliation(s)
- Rachana Rao Battaje
- Department of Biosciences and BioengineeringIndian Institute of Technology Bombay, Mumbai, India
| | - Dulal Panda
- Department of Biosciences and BioengineeringIndian Institute of Technology Bombay, Mumbai, India
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Dutta S, Cruz JA, Imran SM, Chen J, Kramer DM, Osteryoung KW. Variations in chloroplast movement and chlorophyll fluorescence among chloroplast division mutants under light stress. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3541-3555. [PMID: 28645163 PMCID: PMC5853797 DOI: 10.1093/jxb/erx203] [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: 03/10/2017] [Accepted: 05/25/2017] [Indexed: 05/18/2023]
Abstract
Chloroplasts divide to maintain consistent size, shape, and number in leaf mesophyll cells. Altered expression of chloroplast division proteins in Arabidopsis results in abnormal chloroplast morphology. To better understand the influence of chloroplast morphology on chloroplast movement and photosynthesis, we compared the chloroplast photorelocation and photosynthetic responses of a series of Arabidopsis chloroplast division mutants with a wide variety of chloroplast phenotypes. Chloroplast movement was monitored by red light reflectance imaging of whole plants under increasing intensities of white light. The accumulation and avoidance responses were differentially affected in different mutants and depended on both chloroplast number and morphological heterogeneity. Chlorophyll fluorescence measurements during 5 d light experiments demonstrated that mutants with large-chloroplast phenotypes generally exhibited greater PSII photodamage than those with intermediate phenotypes. No abnormalities in photorelocation efficiency or photosynthetic capacity were observed in plants with small-chloroplast phenotypes. Simultaneous measurement of chloroplast movement and chlorophyll fluorescence indicated that the energy-dependent (qE) and long-lived components of non-photochemical quenching that reflect photoinhibition are affected differentially in different division mutants exposed to high or fluctuating light intensities. We conclude that chloroplast division mutants with abnormal chloroplast morphologies differ markedly from the wild type in their light adaptation capabilities, which may decrease their relative fitness in nature.
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Affiliation(s)
- Siddhartha Dutta
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Jeffrey A Cruz
- MSU-DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
- Department of Biochemistry and Molecular Biology Michigan State University, East Lansing, MI, USA
| | - Saif M Imran
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, USA
| | - Jin Chen
- MSU-DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
- Department of Computer Sciences and Engineering, Michigan State University, East Lansing, MI, USA
| | - David M Kramer
- MSU-DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
- Department of Biochemistry and Molecular Biology Michigan State University, East Lansing, MI, USA
- Correspondence: or
| | - Katherine W Osteryoung
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
- Correspondence: or
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24
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ARC6-mediated Z ring-like structure formation of prokaryote-descended chloroplast FtsZ in Escherichia coli. Sci Rep 2017; 7:3492. [PMID: 28615720 PMCID: PMC5471200 DOI: 10.1038/s41598-017-03698-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/04/2017] [Indexed: 12/04/2022] Open
Abstract
Plant chloroplasts proliferate through binary fission, and the stromal-side molecules that are involved in chloroplast division are bacterial derivatives. As in bacteria, the prokaryotic tubulin homolog FtsZ assembles into a ring-like structure (Z ring) at mid-chloroplast, and this process is followed by constriction. However, the properties of chloroplast FtsZs remain unclarified. Here, we employed Escherichia coli as a novel heterologous system for expressing chloroplast FtsZs and their regulatory components. Fluorescently labelled Arabidopsis FtsZ2 efficiently assembled into long filaments in E. coli cells, and artificial membrane tethering conferred FtsZ2 filaments with the ability to form Z ring-like structures resembling the bacterial Z ring. A negative regulator of chloroplast FtsZ assembly, ARC3, retained its inhibitory effects on FtsZ2 filamentation and Z ring-like structure formation in E. coli cells. Thus, we provide a novel heterologous system by using bacterial cells to study the regulation of the chloroplast divisome. Furthermore, we demonstrated that the FtsZ2-interacting protein ARC6, which is a potential candidate for Z ring tethering to the chloroplast inner envelope membrane, genuinely targeted FtsZ2 to the membrane components and supported its morphological shift from linear filaments to Z ring-like structures in a manner dependent on the C-terminal ARC6-interacting domain of FtsZ2.
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25
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Chang N, Sun Q, Li Y, Mu Y, Hu J, Feng Y, Liu X, Gao H. PDV2 has a dosage effect on chloroplast division in Arabidopsis. PLANT CELL REPORTS 2017; 36:471-480. [PMID: 27988788 DOI: 10.1007/s00299-016-2096-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/07/2016] [Indexed: 05/10/2023]
Abstract
PDV2 has a dosage effect on chloroplast division in Arabidopsis thaliana , but this effect may vary in different plants. Chloroplasts have to be divided as plants grow to maintain an optimized number in the cell. Chloroplasts are divided by protein complexes across the double membranes from the stroma side to the cytosolic side. PDV2 is a chloroplast division protein on the chloroplast outer membrane. It recruits the dynamin-related GTPase ARC5 to the division site. The C-terminus of PDV2 and the C-terminus of ARC6 interact in the intermembrane space, which is important for the localization of PDV2. Previously, it was shown that overexpression of PDV2 can increase the division of chloroplasts in Arabidopsis and moss, so the authors concluded that PDV2 determines the rate of chloroplast division in land plants. PDV2 was also shown to inhibit the GTPase activity of ARC5 by in vitro experiment. These results look to be contradictory. Here, we identified a null allele of PDV2 in Arabidopsis and studied plants with different levels of PDV2. Our results suggested that the chloroplast division phenotype in Arabidopsis is sensitive to the level of PDV2, while this is not the case for ARC6. The level of PDV2 protein is reduced sharply in fast-growing leaves, while the level of ARC6 is not. The levels of PDV2 and ARC6 in several other plant species at different developmental stages were also investigated. The results indicated that their expression pattern varies in different species. Thus, PDV2 is an important positive factor of chloroplast division with an apparent dosage effect in Arabidopsis, but this effect for different chloroplast division proteins in different plants may vary.
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Affiliation(s)
- Ning Chang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Qingqing Sun
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Yiqiong Li
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Yajuan Mu
- Beijing Key Lab of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Jinglei Hu
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Yue Feng
- Beijing Key Lab of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Xiaomin Liu
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China.
| | - Hongbo Gao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
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26
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Chen Y, Porter K, Osawa M, Augustus AM, Milam SL, Joshi C, Osteryoung KW, Erickson HP. The Chloroplast Tubulin Homologs FtsZA and FtsZB from the Red Alga Galdieria sulphuraria Co-assemble into Dynamic Filaments. J Biol Chem 2017; 292:5207-5215. [PMID: 28174299 DOI: 10.1074/jbc.m116.767715] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/06/2017] [Indexed: 01/09/2023] Open
Abstract
FtsZ is a homolog of eukaryotic tubulin and is present in almost all bacteria and many archaea, where it is the major cytoskeletal protein in the Z ring, required for cell division. Unlike some other cell organelles of prokaryotic origin, chloroplasts have retained FtsZ as an essential component of the division machinery. However, chloroplast FtsZs have been challenging to study because they are difficult to express and purify. To this end, we have used a FATT tag expression system to produce as soluble proteins the two chloroplast FtsZs from Galdieria sulphuraria, a thermophilic red alga. GsFtsZA and GsFtsZB assembled individually in the presence of GTP, forming large bundles of protofilaments. GsFtsZA also assembled in the presence of GDP, the first member of the FtsZ/tubulin superfamily to do so. Mixtures of GsFtsZA and GsFtsZB assembled protofilament bundles and hydrolyzed GTP at a rate approximately equal to the sum of their individual rates, suggesting a random co-assembly. GsFtsZA assembly by itself in limiting GTP gave polymers that remained stable for a prolonged time. However, when GsFtsZB was added, the co-polymers disassembled with enhanced kinetics, suggesting that the GsFtsZB regulates and enhances disassembly dynamics. GsFtsZA-mts (where mts is a membrane-targeting amphipathic helix) formed Z ring-like helices when expressed in Escherichia coli Co-expression of GsFtsZB (without an mts) gave co-assembly of both into similar helices. In summary, we provide biochemical evidence that GsFtsZA assembles as the primary scaffold of the chloroplast Z ring and that GsFtsZB co-assembly enhances polymer disassembly and dynamics.
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Affiliation(s)
- Yaodong Chen
- From the College of Life Science, Northwest University, Xi'an, ShaanXi, China 710069.,the Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710-3709, and
| | - Katie Porter
- the Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824-1312
| | - Masaki Osawa
- the Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710-3709, and
| | - Anne Marie Augustus
- the Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710-3709, and
| | - Sara L Milam
- the Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710-3709, and
| | - Chandra Joshi
- the Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710-3709, and
| | - Katherine W Osteryoung
- the Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824-1312
| | - Harold P Erickson
- the Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710-3709, and
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27
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Yoshida Y, Mogi Y, TerBush AD, Osteryoung KW. Chloroplast FtsZ assembles into a contractible ring via tubulin-like heteropolymerization. NATURE PLANTS 2016; 2:16095. [PMID: 27322658 DOI: 10.1038/nplants.2016.95] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 05/24/2016] [Indexed: 05/10/2023]
Abstract
Chloroplast division is driven by a ring containing FtsZ1 and FtsZ2 proteins, which originated from bacterial FtsZ, a tubulin-like protein; however, mechanistic details of the chloroplast FtsZ ring remain unclear. Here, we report that FtsZ1 and FtsZ2 can heteropolymerize into a contractible ring ex vivo. Fluorescently labelled FtsZ1 and/or FtsZ2 formed single rings in cells of the yeast Pichia pastoris. Photobleaching experiments indicated that co-assembly of FtsZ1 and FtsZ2 imparts polarity to polymerization. Assembly of FtsZ chimaeras revealed that the protofilaments assemble via heteropolymerization of FtsZ2 and FtsZ1. Contraction of the ring was accompanied by an increase in the filament turnover rate. Our findings suggest that the evolutionary duplication of FtsZ in plants may have increased the mobility and kinetics of FtsZ ring dynamics in chloroplast division. Thus, the gene duplication and heteropolymerization of chloroplast FtsZs may represent convergent evolution with eukaryotic tubulin.
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Affiliation(s)
- Yamato Yoshida
- Department of Plant Biology, Michigan State University, East Lansing 48824-1312, Michigan, USA
| | - Yuko Mogi
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Allan D TerBush
- Department of Plant Biology, Michigan State University, East Lansing 48824-1312, Michigan, USA
| | - Katherine W Osteryoung
- Department of Plant Biology, Michigan State University, East Lansing 48824-1312, Michigan, USA
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28
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TerBush AD, Porzondek CA, Osteryoung KW. Functional Analysis of the Chloroplast Division Complex Using Schizosaccharomyces pombe as a Heterologous Expression System. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:275-289. [PMID: 26917361 DOI: 10.1017/s1431927616000143] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Chloroplast division is driven by a macromolecular complex that assembles at the midplastid. The FtsZ ring (Z ring) is the central structure in this complex, and is composed of the functionally distinct cytoskeletal proteins FtsZ1 and FtsZ2. Recent studies in the heterologous Schizosaccharomyces pombe system showed that Arabidopsis FtsZ1 and FtsZ2 filaments have distinct assembly and turnover characteristics. To further analyze these FtsZs, we employed this system to compare the assembly and dynamic properties of FtsZ1 and FtsZ2 lacking their N- and/or C-termini with those of their full-length counterparts. Our data provide evidence that the N-terminus of FtsZ2 is critical for its structural dominance over FtsZ1, and that the N- and C-termini promote polymer bundling and turnover of both FtsZs and contribute to their distinct behaviors. We also assessed how ARC6 affects FtsZ2 filament dynamics, and found that it interacts with and stabilizes FtsZ2 filaments in S. pombe independent of its presumed Z-ring tethering function in planta. Finally, we generated FtsZ1-FtsZ2 coexpression constructs to facilitate reconstitution of more complex interaction networks. Our experiments yield new insight into factors influencing FtsZ behavior and highlight the utility of S. pombe for analyzing chloroplast FtsZs and their assembly regulators.
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Affiliation(s)
- Allan D TerBush
- 1Biochemistry and Molecular Biology Graduate Program,Michigan State University,East Lansing,MI 48824,USA
| | - Chris A Porzondek
- 3Biochemistry and Molecular Biology Undergraduate Program,Michigan State University,East Lansing,MI 48824,USA
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29
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Zhang M, Chen C, Froehlich JE, TerBush AD, Osteryoung KW. Roles of Arabidopsis PARC6 in Coordination of the Chloroplast Division Complex and Negative Regulation of FtsZ Assembly. PLANT PHYSIOLOGY 2016; 170:250-62. [PMID: 26527658 PMCID: PMC4704591 DOI: 10.1104/pp.15.01460] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/02/2015] [Indexed: 05/08/2023]
Abstract
Chloroplast division is driven by the simultaneous constriction of the inner FtsZ ring (Z ring) and the outer DRP5B ring. The assembly and constriction of these rings in Arabidopsis (Arabidopsis thaliana) are coordinated partly through the inner envelope membrane protein ACCUMULATION AND REPLICATION OF CHLOROPLASTS6 (ARC6). Previously, we showed that PARC6 (PARALOG OF ARC6), also in the inner envelope membrane, negatively regulates FtsZ assembly and acts downstream of ARC6 to position the outer envelope membrane protein PLASTID DIVISION1 (PDV1), which functions together with its paralog PDV2 to recruit DYNAMIN-RELATED PROTEIN 5B (DRP5B) from a cytosolic pool to the outer envelope membrane. However, whether PARC6, like ARC6, also functions in coordination of the chloroplast division contractile complexes was unknown. Here, we report a detailed topological analysis of Arabidopsis PARC6, which shows that PARC6 has a single transmembrane domain and a topology resembling that of ARC6. The newly identified stromal region of PARC6 interacts not only with ARC3, a direct inhibitor of Z-ring assembly, but also with the Z-ring protein FtsZ2. Overexpression of PARC6 inhibits FtsZ assembly in Arabidopsis but not in a heterologous yeast system (Schizosaccharomyces pombe), suggesting that the negative regulation of FtsZ assembly by PARC6 is a consequence of its interaction with ARC3. A conserved carboxyl-terminal peptide in FtsZ2 mediates FtsZ2 interaction with both PARC6 and ARC6. Consistent with its role in the positioning of PDV1, the intermembrane space regions of PARC6 and PDV1 interact. These findings provide new insights into the functions of PARC6 and suggest that PARC6 coordinates the inner Z ring and outer DRP5B ring through interaction with FtsZ2 and PDV1 during chloroplast division.
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Affiliation(s)
- Min Zhang
- Department of Plant Biology (M.Z., C.C., A.D.T., K.W.O.), Michigan State University-Department of Energy Plant Research Laboratory (J.E.F.), and Department of Biochemistry and Molecular Biology (J.E.F.), Michigan State University, East Lansing, Michigan 48824; andCollege of Life Sciences, Capital Normal University, Beijing 100048, China (M.Z.)
| | - Cheng Chen
- Department of Plant Biology (M.Z., C.C., A.D.T., K.W.O.), Michigan State University-Department of Energy Plant Research Laboratory (J.E.F.), and Department of Biochemistry and Molecular Biology (J.E.F.), Michigan State University, East Lansing, Michigan 48824; andCollege of Life Sciences, Capital Normal University, Beijing 100048, China (M.Z.)
| | - John E Froehlich
- Department of Plant Biology (M.Z., C.C., A.D.T., K.W.O.), Michigan State University-Department of Energy Plant Research Laboratory (J.E.F.), and Department of Biochemistry and Molecular Biology (J.E.F.), Michigan State University, East Lansing, Michigan 48824; andCollege of Life Sciences, Capital Normal University, Beijing 100048, China (M.Z.)
| | - Allan D TerBush
- Department of Plant Biology (M.Z., C.C., A.D.T., K.W.O.), Michigan State University-Department of Energy Plant Research Laboratory (J.E.F.), and Department of Biochemistry and Molecular Biology (J.E.F.), Michigan State University, East Lansing, Michigan 48824; andCollege of Life Sciences, Capital Normal University, Beijing 100048, China (M.Z.)
| | - Katherine W Osteryoung
- Department of Plant Biology (M.Z., C.C., A.D.T., K.W.O.), Michigan State University-Department of Energy Plant Research Laboratory (J.E.F.), and Department of Biochemistry and Molecular Biology (J.E.F.), Michigan State University, East Lansing, Michigan 48824; andCollege of Life Sciences, Capital Normal University, Beijing 100048, China (M.Z.)
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30
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Hirakawa Y, Ishida KI. Prospective function of FtsZ proteins in the secondary plastid of chlorarachniophyte algae. BMC PLANT BIOLOGY 2015; 15:276. [PMID: 26556725 PMCID: PMC4641359 DOI: 10.1186/s12870-015-0662-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 11/03/2015] [Indexed: 05/15/2023]
Abstract
BACKGROUND Division of double-membraned plastids (primary plastids) is performed by constriction of a ring-like division complex consisting of multiple plastid division proteins. Consistent with the endosymbiotic origin of primary plastids, some of the plastid division proteins are descended from cyanobacterial cell division machinery, and the others are of host origin. In several algal lineages, complex plastids, the "secondary plastids", have been acquired by the endosymbiotic uptake of primary plastid-bearing algae, and are surrounded by three or four membranes. Although homologous genes for primary plastid division proteins have been found in genome sequences of secondary plastid-bearing organisms, little is known about the function of these proteins or the mechanism of secondary plastid division. RESULTS To gain insight into the mechanism of secondary plastid division, we characterized two plastid division proteins, FtsZD-1 and FtsZD-2, in chlorarachniophyte algae. FtsZ homologs were encoded by the nuclear genomes and carried an N-terminal plastid targeting signal. Immunoelectron microscopy revealed that both FtsZD-1 and FtsZD-2 formed a ring-like structure at the midpoint of bilobate plastids with a projecting pyrenoid in Bigelowiella natans. The ring was always associated with a shallow plate-like invagination of the two innermost plastid membranes. Furthermore, gene expression analysis confirmed that transcripts of ftsZD genes were periodically increased soon after cell division during the B. natans cell cycle, which is not consistent with the timing of plastid division. CONCLUSIONS Our findings suggest that chlorarachniophyte FtsZD proteins are involved in partial constriction of the inner pair of plastid membranes, but not in the whole process of plastid division. It is uncertain how the outer pair of plastid membranes is constricted, and as-yet-unknown mechanism is required for the secondary plastid division in chlorarachniophytes.
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Affiliation(s)
- Yoshihisa Hirakawa
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
| | - Ken-ichiro Ishida
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
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31
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Johnson CB, Shaik R, Abdallah R, Vitha S, Holzenburg A. FtsZ1/FtsZ2 Turnover in Chloroplasts and the Role of ARC3. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2015; 21:313-23. [PMID: 25731613 DOI: 10.1017/s1431927615000082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Chloroplast division requires filamentation temperature-sensitive Z (FtsZ), a tubulin-like GTPase of cyanobacterial endosymbiotic origin. Plants and algae possess two distinct FtsZ protein families, FtsZ1 and FtsZ2 that co-assemble into a ring (Z-ring) at the division site. Z-ring assembly and disassembly and division site positioning is controlled by both positive and negative factors via their specific interactions with FtsZ1 and FtsZ2. Here we present the in planta analysis of Arabidopsis FtsZ1 and FtsZ2 turnover in the context of a native chloroplast division machinery. Fluorescence recovery after photobleaching analysis was conducted using fluorescently tagged FtsZ at wild-type (WT)-like levels. Rapid photobleaching, low signal-to-noise ratio, and phototropic movements of chloroplasts were overcome by (i) using progressive intervals in time-lapse imaging, (ii) analyzing epidermal rather than stromal chloroplasts, and (iii) employing image stack alignment during postprocessing. In plants of WT background, fluorescence recovery half-times averaged 117 and 325 s for FtsZ1 and FtsZ2, respectively. In plants lacking ARC3, the key negative regulator of FtsZ assembly, the turnover was threefold slower. The findings are discussed in the context of previous results conducted in a heterologous system.
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Affiliation(s)
- Carol B Johnson
- 1Microscopy & Imaging Center,Texas A&M University,College Station,TX 77843-2257,USA
| | - Rahamthulla Shaik
- 2Department of Biology,Texas A&M University,College Station,TX 77843-3258,USA
| | - Rehab Abdallah
- 2Department of Biology,Texas A&M University,College Station,TX 77843-3258,USA
| | - Stanislav Vitha
- 1Microscopy & Imaging Center,Texas A&M University,College Station,TX 77843-2257,USA
| | - Andreas Holzenburg
- 1Microscopy & Imaging Center,Texas A&M University,College Station,TX 77843-2257,USA
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Kamau PK, Sano S, Takami T, Matsushima R, Maekawa M, Sakamoto W. A Mutation in GIANT CHLOROPLAST Encoding a PARC6 Homolog Affects Spikelet Fertility in Rice. ACTA ACUST UNITED AC 2015; 56:977-91. [DOI: 10.1093/pcp/pcv024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 02/04/2015] [Indexed: 01/07/2023]
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Abstract
Plastid division is fundamental to the biology of plant cells. Division by binary fission entails the coordinated assembly and constriction of four concentric rings, two internal and two external to the organelle. The internal FtsZ ring and external dynamin-like ARC5/DRP5B ring are connected across the two envelopes by the membrane proteins ARC6, PARC6, PDV1, and PDV2. Assembly-stimulated GTPase activity drives constriction of the FtsZ and ARC5/DRP5B rings, which together with the plastid-dividing rings pull and squeeze the envelope membranes until the two daughter plastids are formed, with the final separation requiring additional proteins. The positioning of the division machinery is controlled by the chloroplast Min system, which confines FtsZ-ring formation to the plastid midpoint. The dynamic morphology of plastids, especially nongreen plastids, is also considered here, particularly in relation to the production of stromules and plastid-derived vesicles and their possible roles in cellular communication and plastid functionality.
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34
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The FtsZ-like protein FtsZm of Magnetospirillum gryphiswaldense likely interacts with its generic homolog and is required for biomineralization under nitrate deprivation. J Bacteriol 2013; 196:650-9. [PMID: 24272781 DOI: 10.1128/jb.00804-13] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Midcell selection, septum formation, and cytokinesis in most bacteria are orchestrated by the eukaryotic tubulin homolog FtsZ. The alphaproteobacterium Magnetospirillum gryphiswaldense (MSR-1) septates asymmetrically, and cytokinesis is linked to splitting and segregation of an intracellular chain of membrane-enveloped magnetite crystals (magnetosomes). In addition to a generic, full-length ftsZ gene, MSR-1 contains a truncated ftsZ homolog (ftsZm) which is located adjacent to genes controlling biomineralization and magnetosome chain formation. We analyzed the role of FtsZm in cell division and biomineralization together with the full-length MSR-1 FtsZ protein. Our results indicate that loss of FtsZm has a strong effect on microoxic magnetite biomineralization which, however, could be rescued by the presence of nitrate in the medium. Fluorescence microscopy revealed that FtsZm-mCherry does not colocalize with the magnetosome-related proteins MamC and MamK but is confined to asymmetric spots at midcell and at the cell pole, coinciding with the FtsZ protein position. In Escherichia coli, both FtsZ homologs form distinct structures but colocalize when coexpressed, suggesting an FtsZ-dependent recruitment of FtsZm. In vitro analyses indicate that FtsZm is able to interact with the FtsZ protein. Together, our data suggest that FtsZm shares key features with its full-length homolog but is involved in redox control for magnetite crystallization.
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35
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TerBush AD, Yoshida Y, Osteryoung KW. FtsZ in chloroplast division: structure, function and evolution. Curr Opin Cell Biol 2013; 25:461-70. [DOI: 10.1016/j.ceb.2013.04.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 04/06/2013] [Accepted: 04/23/2013] [Indexed: 11/30/2022]
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36
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Zhang M, Schmitz AJ, Kadirjan-Kalbach DK, TerBush AD, Osteryoung KW. Chloroplast division protein ARC3 regulates chloroplast FtsZ-ring assembly and positioning in arabidopsis through interaction with FtsZ2. THE PLANT CELL 2013; 25:1787-802. [PMID: 23715471 PMCID: PMC3694706 DOI: 10.1105/tpc.113.111047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Chloroplast division is initiated by assembly of a mid-chloroplast FtsZ (Z) ring comprising two cytoskeletal proteins, FtsZ1 and FtsZ2. The division-site regulators ACCUMULATION AND REPLICATION OF CHLOROPLASTS3 (ARC3), MinD1, and MinE1 restrict division to the mid-plastid, but their roles are poorly understood. Using genetic analyses in Arabidopsis thaliana, we show that ARC3 mediates division-site placement by inhibiting Z-ring assembly, and MinD1 and MinE1 function through ARC3. ftsZ1 null mutants exhibited some mid-plastid FtsZ2 rings and constrictions, whereas neither constrictions nor FtsZ1 rings were observed in mutants lacking FtsZ2, suggesting FtsZ2 is the primary determinant of Z-ring assembly in vivo. arc3 ftsZ1 double mutants exhibited multiple parallel but no mid-plastid FtsZ2 rings, resembling the Z-ring phenotype in arc3 single mutants and showing that ARC3 affects positioning of FtsZ2 rings as well as Z rings. ARC3 overexpression in the wild type and ftsZ1 inhibited Z-ring and FtsZ2-ring assembly, respectively. Consistent with its effects in vivo, ARC3 interacted with FtsZ2 in two-hybrid assays and inhibited FtsZ2 assembly in a heterologous system. Our studies are consistent with a model wherein ARC3 directly inhibits Z-ring assembly in vivo primarily through interaction with FtsZ2 in heteropolymers and suggest that ARC3 activity is spatially regulated by MinD1 and MinE1 to permit Z-ring assembly at the mid-plastid.
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Affiliation(s)
- Min Zhang
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Aaron J. Schmitz
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Cell and Molecular Biology Graduate Program, Michigan State University, East Lansing, Michigan 48824
- Department of Energy–Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
| | | | - Allan D. TerBush
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Biochemistry and Molecular Biology Graduate Program, Michigan State University, East Lansing, Michigan 48824
| | - Katherine W. Osteryoung
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Address correspondence to
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Basak I, Møller SG. Emerging facets of plastid division regulation. PLANTA 2013; 237:389-98. [PMID: 22965912 DOI: 10.1007/s00425-012-1743-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 08/19/2012] [Indexed: 05/08/2023]
Abstract
Plastids are complex organelles that are integrated into the plant host cell where they differentiate and divide in tune with plant differentiation and development. In line with their prokaryotic origin, plastid division involves both evolutionary conserved proteins and proteins of eukaryotic origin where the host has acquired control over the process. The plastid division apparatus is spatially separated between the stromal and the cytosolic space but where clear coordination mechanisms exist between the two machineries. Our knowledge of the plastid division process has increased dramatically during the past decade and recent findings have not only shed light on plastid division enzymology and the formation of plastid division complexes but also on the integration of the division process into a multicellular context. This review summarises our current knowledge of plastid division with an emphasis on biochemical features, the functional assembly of protein complexes and regulatory features of the overall process.
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Affiliation(s)
- Indranil Basak
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, NY 11439, USA
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Gargano D, Maple-Grødem J, Reisinger V, Eichacker LA, Møller SG. Analysis of the chloroplast proteome in arc mutants and identification of novel protein components associated with FtsZ2. PLANT MOLECULAR BIOLOGY 2013; 81:235-44. [PMID: 23225155 DOI: 10.1007/s11103-012-9994-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 11/28/2012] [Indexed: 05/21/2023]
Abstract
Chloroplasts are descendants of cyanobacteria and divide by binary fission. The number of chloroplasts is regulated in a cell type-specific manner to ensure that specialized cell types can perform their functions optimally. Several protein components of the chloroplast division apparatus have been identified in the past several years, but how this process is regulated in response to developmental status, environmental signals and stress is still unknown. To begin to address this we undertook a proteomic analysis of three accumulation and replication of chloroplasts mutants that show a spectrum of plastid division perturbations. We show that defects in the chloroplast division process results in changes in the abundance of proteins when compared to wild type, but that the profile of the native stromal and membrane complexes remains unchanged. Furthermore, by combining BN-PAGE with protein interaction assays we show that AtFtsZ2-1 and AtFtsZ2-2 assemble together with rpl12A and EF-Tu into a novel chloroplast membrane complex.
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Affiliation(s)
- Daniela Gargano
- Centre for Organelle Research, University of Stavanger, Stavanger, Norway
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Ludueña RF. A Hypothesis on the Origin and Evolution of Tubulin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 302:41-185. [DOI: 10.1016/b978-0-12-407699-0.00002-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Abstract
The tubulin-like FtsZ protein initiates assembly of the bacterial and plastid division machineries. In bacteria, phosphorylation of FtsZ impairs GTPase activity, polymerization and interactions with other division proteins. Using a proteomics approach, we have shown that AtFtsZ2 is phosphorylated in vivo in Arabidopsis and that PGK1 (phosphoglycerate kinase 1) interacts with AtFtsZ2 in planta, suggesting a possible role in FtsZ phosphorylation.
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TerBush AD, Osteryoung KW. Distinct functions of chloroplast FtsZ1 and FtsZ2 in Z-ring structure and remodeling. J Cell Biol 2012; 199:623-37. [PMID: 23128242 PMCID: PMC3494859 DOI: 10.1083/jcb.201205114] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 10/12/2012] [Indexed: 12/19/2022] Open
Abstract
FtsZ, a cytoskeletal GTPase, forms a contractile ring for cell division in bacteria and chloroplast division in plants. Whereas bacterial Z rings are composed of a single FtsZ, those in chloroplasts contain two distinct FtsZ proteins, FtsZ1 and FtsZ2, whose functional relationship is poorly understood. We expressed fluorescently tagged FtsZ1 and FtsZ2 in fission yeast to investigate their intrinsic assembly and dynamic properties. FtsZ1 and FtsZ2 formed filaments with differing morphologies when expressed separately. FRAP showed that FtsZ2 filaments were less dynamic than FtsZ1 filaments and that GTPase activity was essential for FtsZ2 filament turnover but may not be solely responsible for FtsZ1 turnover. When coexpressed, the proteins colocalized, consistent with coassembly, but exhibited an FtsZ2-like morphology. However, FtsZ1 increased FtsZ2 exchange into coassembled filaments. Our findings suggest that FtsZ2 is the primary determinant of chloroplast Z-ring structure, whereas FtsZ1 facilitates Z-ring remodeling. We also demonstrate that ARC3, a regulator of chloroplast Z-ring positioning, functions as an FtsZ1 assembly inhibitor.
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Affiliation(s)
- Allan D. TerBush
- Biochemistry and Molecular Biology Graduate Program and Department of Plant Biology, Michigan State University, East Lansing, MI 48824
| | - Katherine W. Osteryoung
- Biochemistry and Molecular Biology Graduate Program and Department of Plant Biology, Michigan State University, East Lansing, MI 48824
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Structure, regulation, and evolution of the plastid division machinery. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 291:115-53. [PMID: 22017975 DOI: 10.1016/b978-0-12-386035-4.00004-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Plastids have evolved from a cyanobacterial endosymbiont, and their continuity is maintained by the plastid division and segregation which is regulated by the eukaryotic host cell. Plastids divide by constriction of the inner- and outer-envelope membranes. Recent studies revealed that this constriction is performed by a large protein and glucan complex at the division site that spans the two envelope membranes. The division complex has retained certain components of the cyanobacterial division complex along with components developed by the host cell. Based on the information on the division complex at the molecular level, we are beginning to understand how the division complex has evolved and how it is assembled, constricted, and regulated in the host cell. This chapter reviews the current understanding of the plastid division machinery and some of the questions that will be addressed in the near future.
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Wilson ME, Jensen GS, Haswell ES. Two mechanosensitive channel homologs influence division ring placement in Arabidopsis chloroplasts. THE PLANT CELL 2011; 23:2939-49. [PMID: 21810996 PMCID: PMC3180802 DOI: 10.1105/tpc.111.088112] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 07/14/2011] [Accepted: 07/18/2011] [Indexed: 05/18/2023]
Abstract
Chloroplasts must divide repeatedly to maintain their population during plant growth and development. A number of proteins required for chloroplast division have been identified, and the functional relationships between them are beginning to be elucidated. In both chloroplasts and bacteria, the future site of division is specified by placement of the Filamentous temperature sensitive Z (FtsZ) ring, and the Min system serves to restrict FtsZ ring formation to mid-chloroplast or mid-cell. How the Min system is regulated in response to environmental and developmental factors is largely unstudied. Here, we investigated the role in chloroplast division played by two Arabidopsis thaliana homologs of the bacterial mechanosensitive (MS) channel MscS: MscS-Like 2 (MSL2) and MSL3. Immunofluorescence microscopy and live imaging approaches demonstrated that msl2 msl3 double mutants have enlarged chloroplasts containing multiple FtsZ rings. Genetic analyses indicate that MSL2, MSL3, and components of the Min system function in the same pathway to regulate chloroplast size and FtsZ ring formation. In addition, an Escherichia coli strain lacking MS channels also showed aberrant FtsZ ring assembly. These results establish MS channels as components of the chloroplast division machinery and suggest that their role is evolutionarily conserved.
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Smith AG, Johnson CB, Vitha S, Holzenburg A. Oligomerization of plant FtsZ1 and FtsZ2 plastid division proteins. Arch Biochem Biophys 2011; 513:94-101. [PMID: 21781955 DOI: 10.1016/j.abb.2011.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/22/2011] [Accepted: 07/01/2011] [Indexed: 11/26/2022]
Abstract
FtsZ was identified in bacteria as the first protein to localize mid-cell prior to division and homologs have been found in many plant species. Bacterial studies demonstrated that FtsZ forms a ring structure that is dynamically exchanged with a soluble pool of FtsZ. Our previous work established that Arabidopsis FtsZ1 and FtsZ2-1 are capable of in vitro self-assembly into two distinct filament types, termed type-I and type-II and noted the presence of filament precursor molecules which prompted this investigation. Using a combination of electron microscopy, gel chromatography and native PAGE revealed that (i) prior to FtsZ assembly initiation the pool consists solely of dimers and (ii) during assembly of the Arabidopsis FtsZ type-II filaments the most common intermediate between the dimer and filament state is a tetramer. Three-dimensional reconstructions of the observed dimer and tetramer suggest these oligomeric forms may represent consecutive steps in type-II filament assembly and a mechanism is proposed, which is expanded to include FtsZ assembly into type-I filaments. Finally, the results permit a discussion of the oligomeric nature of the soluble pool in plants.
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Affiliation(s)
- Aaron G Smith
- Microscopy and Imaging Center, Texas A&M University, College Station, TX 77843-2257, USA
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Hanson MR, Sattarzadeh A. Stromules: recent insights into a long neglected feature of plastid morphology and function. PLANT PHYSIOLOGY 2011; 155:1486-92. [PMID: 21330493 PMCID: PMC3091082 DOI: 10.1104/pp.110.170852] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 02/16/2011] [Indexed: 05/20/2023]
Affiliation(s)
- Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA.
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Karamoko M, El-Kafafi ES, Mandaron P, Lerbs-Mache S, Falconet D. Multiple FtsZ2 isoforms involved in chloroplast division and biogenesis are developmentally associated with thylakoid membranes in Arabidopsis. FEBS Lett 2011; 585:1203-8. [PMID: 21439281 DOI: 10.1016/j.febslet.2011.03.041] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 03/11/2011] [Accepted: 03/18/2011] [Indexed: 11/17/2022]
Abstract
Seed plants and algae have two distinct FtsZ protein families, FtsZ1 and FtsZ2, involved in plastid division. Distinctively, seed plants and mosses contain two FtsZ2 family members (FtsZ2-1 and FtsZ2-2) thus raising the question of the role of these FtsZ2 paralogs in plants. We show that both FtsZ2 paralogs, in addition to being present in the stroma, are associated with the thylakoid membranes and that association is developmentally regulated. We also show that several FtsZ2-1 isoforms are present with distinct intra-plastidial localization. Mutant analyses show that FtsZ2-1 is essential for chloroplast division and that FtsZ2-2 plays a specific role in chloroplast morphology and internal organisation in addition to participating in chloroplast partition.
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Affiliation(s)
- Mohamed Karamoko
- Laboratoire de Physiologie Cellulaire Végétale, CNRS-(UMR5168)/INRA-(UMR1200)/UJF-Grenoble 1/CEA-iRTSV, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 Rue des Martyrs, F-38054 Grenoble, France
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Aylett CH, Löwe J, Amos LA. New Insights into the Mechanisms of Cytomotive Actin and Tubulin Filaments. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 292:1-71. [DOI: 10.1016/b978-0-12-386033-0.00001-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Miyagishima SY, Kabeya Y. Chloroplast division: squeezing the photosynthetic captive. Curr Opin Microbiol 2010; 13:738-46. [PMID: 21041111 DOI: 10.1016/j.mib.2010.10.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 09/28/2010] [Accepted: 10/06/2010] [Indexed: 10/18/2022]
Abstract
Chloroplasts have evolved from a cyanobacterial endosymbiont and have been retained in eukaryotic cells for more than one billion years via chloroplast division and inheritance by daughter cells during cell division. Recent studies revealed that chloroplast division is performed by a large protein complex at the division site, encompassing both the inside and the outside of the two envelope membranes. The division complex has retained a few components of the cyanobacterial division complex to go along with other components supplied by the host cell. On the basis of the information about the division complex, we are beginning to understand how the division complex evolved, and how eukaryotic host cells regulate chloroplast division during proliferation and differentiation.
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Affiliation(s)
- Shin-Ya Miyagishima
- Initiative Research Program, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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Pyke KA. Plastid division. AOB PLANTS 2010; 2010:plq016. [PMID: 22476074 PMCID: PMC2995336 DOI: 10.1093/aobpla/plq016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 08/19/2010] [Accepted: 09/28/2010] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Plastids undergo a process of binary fission in order to replicate. Plastid replication is required at two distinct stages of plant growth: during cell division to ensure correct plastid segregation, and during cell expansion and development to generate large populations of functional plastids, as in leaf mesophyll cells. This review considers some of the recent advances in the understanding of how plastids undergo binary fission, a process which uses several different proteins, both internal and external to the plastid, which have been derived from the original endosymbiont's genome as well as new proteins that have been recruited from the host genome. KEY POINTS Several of the proteins currently used in this process in higher plants have homologues in modern-day bacteria. An alternative mode of replication by a budding-type mechanism also appears to be used in some circumstances. The review also highlights how most of our knowledge of plastid division is centred on the chloroplast developing in leaf mesophyll cells and a role for plastid division during the development of other plastid types is poorly understood. Whilst models for a protein-based mechanism have been devised, exactly how the division process is controlled at the plastid level and at the plastid population level is poorly understood.
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Affiliation(s)
- Kevin Andrew Pyke
- Plant and Crop Sciences Division , School of Biosciences, University of Nottingham , Sutton Bonington Campus, Loughborough LE12 5RD , UK
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