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Rathod MK, Nellaepalli S, Ozawa SI, Kuroda H, Kodama N, Bujaldon S, Wollman FA, Takahashi Y. Assembly Apparatus of Light-Harvesting Complexes: Identification of Alb3.1-cpSRP-LHCP Complexes in the Green Alga Chlamydomonas reinhardtii. PLANT & CELL PHYSIOLOGY 2022; 63:70-81. [PMID: 34592750 DOI: 10.1093/pcp/pcab146] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 09/24/2021] [Accepted: 09/30/2021] [Indexed: 06/13/2023]
Abstract
The unicellular green alga, Chlamydomonas reinhardtii, contains many light-harvesting complexes (LHCs) associating chlorophylls a/b and carotenoids; the major LHCIIs (types I, II, III and IV) and minor light-harvesting complexes, CP26 and CP29, for photosystem II, as well as nine LHCIs (LHCA1-9), for photosystem I. A pale green mutant BF4 exhibited impaired accumulation of LHCs due to deficiency in the Alb3.1 gene, which encodes the insertase involved in insertion, folding and assembly of LHC proteins in the thylakoid membranes. To elucidate the molecular mechanism by which ALB3.1 assists LHC assembly, we complemented BF4 to express ALB3.1 fused with no, single or triple Human influenza hemagglutinin (HA) tag at its C-terminus (cAlb3.1, cAlb3.1-HA or cAlb3.1-3HA). The resulting complemented strains accumulated most LHC proteins comparable to wild-type (WT) levels. The affinity purification of Alb3.1-HA and Alb3.1-3HA preparations showed that ALB3.1 interacts with cpSRP43 and cpSRP54 proteins of the chloroplast signal recognition particle (cpSRP) and several LHC proteins; two major LHCII proteins (types I and III), two minor LHCII proteins (CP26 and CP29) and eight LHCI proteins (LHCA1, 2, 3, 4, 5, 6, 8 and 9). Pulse-chase labeling experiments revealed that the newly synthesized major LHCII proteins were transiently bound to the Alb3.1 complex. We propose that Alb3.1 interacts with cpSRP43 and cpSRP54 to form an assembly apparatus for most LHCs in the thylakoid membranes. Interestingly, photosystem I (PSI) proteins were also detected in the Alb3.1 preparations, suggesting that the integration of LHCIs to a PSI core complex to form a PSI-LHCI subcomplex occurs before assembled LHCIs dissociate from the Alb3.1-cpSRP complex.
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Affiliation(s)
- Mithun Kumar Rathod
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530 Japan
| | - Sreedhar Nellaepalli
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530 Japan
| | - Shin-Ichiro Ozawa
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046 Japan
| | - Hiroshi Kuroda
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530 Japan
| | - Natsumi Kodama
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530 Japan
| | - Sandrine Bujaldon
- Institut de Biologie Physico-Chimique, UMR7141 CNRS-Sorbonne Université, Paris 75005, France
| | - Francis-André Wollman
- Institut de Biologie Physico-Chimique, UMR7141 CNRS-Sorbonne Université, Paris 75005, France
| | - Yuichiro Takahashi
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530 Japan
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Kleiner FH, Vesteg M, Steiner JM. An ancient glaucophyte c6-like cytochrome related to higher plant cytochrome c6A is imported into muroplasts. J Cell Sci 2021; 134:261815. [DOI: 10.1242/jcs.255901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/29/2021] [Indexed: 12/13/2022] Open
Abstract
Abstract
Cytochrome c6 is a redox carrier in the thylakoid lumen of cyanobacteria and some eukaryotic algae. Although the isofunctional plastocyanin is present in land plants and the green alga Chlamydomonas reinhardtii, these organisms also possess a cytochrome c6-like protein designated as cytochrome c6A. Two other cytochrome c6-like groups, c6B and c6C, have been identified in cyanobacteria. In this study, we have identified a novel c6-like cytochrome called PetJ2, which is encoded in the nuclear genome of Cyanophora paradoxa, a member of the glaucophytes – the basal branch of the Archaeplastida. We propose that glaucophyte PetJ2 protein is related to cyanobacterial c6B and c6C cytochromes, and that cryptic green algal and land plant cytochromes c6A evolved from an ancestral archaeplastidial PetJ2 protein. In vitro import experiments with isolated muroplasts revealed that PetJ2 is imported into plastids. Although it harbors a twin-arginine motif in its thylakoid-targeting peptide, which is generally indicative of thylakoid import via the Tat import pathway, our import experiments with isolated muroplasts and the heterologous pea thylakoid import system revealed that PetJ2 uses the Sec pathway instead of the Tat import pathway.
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Affiliation(s)
- Friedrich Hans Kleiner
- Institute of Biology – Plant Physiology, Martin Luther University Halle-Wittenberg, Halle/Saale 06099, Germany
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
- School of Ocean and Earth Science, University of Southampton, Southampton SO14 3ZH, UK
| | - Matej Vesteg
- Department of Biology and Ecology, Faculty of Natural Sciences, Matej Bel University, 974 01, Banská Bystrica, Slovakia
| | - Jürgen Michael Steiner
- Institute of Biology – Plant Physiology, Martin Luther University Halle-Wittenberg, Halle/Saale 06099, Germany
- Department of Biology and Ecology, Faculty of Natural Sciences, Matej Bel University, 974 01, Banská Bystrica, Slovakia
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The BF4 and p71 antenna mutants from Chlamydomonas reinhardtii. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148085. [PMID: 31672413 DOI: 10.1016/j.bbabio.2019.148085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 08/28/2019] [Accepted: 09/11/2019] [Indexed: 11/23/2022]
Abstract
Two pale green mutants of the green alga Chlamydomonas reinhardtii, which have been used over the years in many photosynthesis studies, the BF4 and p71 mutants, were characterized and their mutated gene identified in the nuclear genome. The BF4 mutant is defective in the insertase Alb3.1 whereas p71 is defective in cpSRP43. The two mutants showed strikingly similar deficiencies in most of the peripheral antenna proteins associated with either photosystem I or photosystem 2. As a result the two photosystems have a reduced antenna size with photosystem 2 being the most affected. Still up to 20% of the antenna proteins remain in these strains, with the heterodimer Lhca5/Lhca6 showing a lower sensitivity to these mutations. We discuss these phenotypes in light of those of other allelic mutants that have been described in the literature and suggest that eventhough the cpSRP route serves as the main biogenesis pathway for antenna proteins, there should be an escape pathway which remains to be genetically identified.
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Ziehe D, Dünschede B, Schünemann D. Molecular mechanism of SRP-dependent light-harvesting protein transport to the thylakoid membrane in plants. PHOTOSYNTHESIS RESEARCH 2018; 138:303-313. [PMID: 29956039 PMCID: PMC6244792 DOI: 10.1007/s11120-018-0544-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 06/20/2018] [Indexed: 05/26/2023]
Abstract
The light-harvesting chlorophyll a/b binding proteins (LHCP) belong to a large family of membrane proteins. They form the antenna complexes of photosystem I and II and function in light absorption and transfer of the excitation energy to the photosystems. As nuclear-encoded proteins, the LHCPs are imported into the chloroplast and further targeted to their final destination-the thylakoid membrane. Due to their hydrophobicity, the formation of the so-called 'transit complex' in the stroma is important to prevent their aggregation in this aqueous environment. The posttranslational LHCP targeting mechanism is well regulated through the interaction of various soluble and membrane-associated protein components and includes several steps: the binding of the LHCP to the heterodimeric cpSRP43/cpSRP54 complex to form the soluble transit complex; the docking of the transit complex to the SRP receptor cpFtsY and the Alb3 translocase at the membrane followed by the release and integration of the LHCP into the thylakoid membrane in a GTP-dependent manner. This review summarizes the molecular mechanisms and dynamics behind the posttranslational LHCP targeting to the thylakoid membrane of Arabidopsis thaliana.
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Affiliation(s)
- Dominik Ziehe
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Beatrix Dünschede
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Danja Schünemann
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, Universitätsstraße 150, 44780, Bochum, Germany.
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Chloroplast SRP43 acts as a chaperone for glutamyl-tRNA reductase, the rate-limiting enzyme in tetrapyrrole biosynthesis. Proc Natl Acad Sci U S A 2018; 115:E3588-E3596. [PMID: 29581280 DOI: 10.1073/pnas.1719645115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Assembly of light-harvesting complexes requires synchronization of chlorophyll (Chl) biosynthesis with biogenesis of light-harvesting Chl a/b-binding proteins (LHCPs). The chloroplast signal recognition particle (cpSRP) pathway is responsible for transport of nucleus-encoded LHCPs in the stroma of the plastid and their integration into the thylakoid membranes. Correct folding and assembly of LHCPs require the incorporation of Chls, whose biosynthesis must therefore be precisely coordinated with membrane insertion of LHCPs. How the spatiotemporal coordination between the cpSRP machinery and Chl biosynthesis is achieved is poorly understood. In this work, we demonstrate a direct interaction between cpSRP43, the chaperone that mediates LHCP targeting and insertion, and glutamyl-tRNA reductase (GluTR), a rate-limiting enzyme in tetrapyrrole biosynthesis. Concurrent deficiency for cpSRP43 and the GluTR-binding protein (GBP) additively reduces GluTR levels, indicating that cpSRP43 and GBP act nonredundantly to stabilize GluTR. The substrate-binding domain of cpSRP43 binds to the N-terminal region of GluTR, which harbors aggregation-prone motifs, and the chaperone activity of cpSRP43 efficiently prevents aggregation of these regions. Our work thus reveals a function of cpSRP43 in Chl biosynthesis and suggests a striking mechanism for posttranslational coordination of LHCP insertion with Chl biosynthesis.
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Jeong J, Baek K, Yu J, Kirst H, Betterle N, Shin W, Bae S, Melis A, Jin E. Deletion of the chloroplast LTD protein impedes LHCI import and PSI-LHCI assembly in Chlamydomonas reinhardtii. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:1147-1158. [PMID: 29300952 PMCID: PMC6018721 DOI: 10.1093/jxb/erx457] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 12/12/2017] [Indexed: 05/26/2023]
Abstract
Nuclear-encoded light-harvesting chlorophyll- and carotenoid-binding proteins (LHCPs) are imported into the chloroplast and transported across the stroma to thylakoid membrane assembly sites by the chloroplast signal recognition particle (CpSRP) pathway. The LHCP translocation defect (LTD) protein is essential for the delivery of imported LHCPs to the CpSRP pathway in Arabidopsis. However, the function of the LTD protein in Chlamydomonas reinhardtii has not been investigated. Here, we generated a C. reinhardtii ltd (Crltd) knockout mutant by using CRISPR-Cas9, a new target-specific knockout technology. The Crltd1 mutant showed a low chlorophyll content per cell with an unusual increase in appressed thylakoid membranes and enlarged cytosolic vacuoles. Profiling of thylakoid membrane proteins in the Crltd1 mutant showed a more severe reduction in the levels of photosystem I (PSI) core proteins and absence of functional LHCI compared with those of photosystem II, resulting in a much smaller PSI pool size and diminished chlorophyll antenna size. The lack of CrLTD did not prevent photoautotrophic growth of the cells. These results are substantially different from those for Arabidopsis ltd null mutant, indicating LTD function in LHCP delivery and PSI assembly may not be as stringent in C. reinhardtii as it is in higher plants.
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Affiliation(s)
- Jooyeon Jeong
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, Korea
| | - Kwangryul Baek
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, Korea
| | - Jihyeon Yu
- School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Henning Kirst
- Department of Plant and Microbial Biology, University of California, Berkeley, California USA
| | - Nico Betterle
- Department of Plant and Microbial Biology, University of California, Berkeley, California USA
| | - Woongghi Shin
- Department of Biology, Chungnam National University, Daejeon, Korea
| | - Sangsu Bae
- Department of Chemistry, Hanyang University, Seoul, Korea
| | - Anastasios Melis
- Department of Plant and Microbial Biology, University of California, Berkeley, California USA
| | - EonSeon Jin
- Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul, Korea
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Króliczewski J, Bartoszewski R, Króliczewska B. Chloroplast PetD protein: evidence for SRP/Alb3-dependent insertion into the thylakoid membrane. BMC PLANT BIOLOGY 2017; 17:213. [PMID: 29162052 PMCID: PMC5697057 DOI: 10.1186/s12870-017-1176-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 11/13/2017] [Indexed: 05/24/2023]
Abstract
BACKGROUND In thylakoid membrane, each monomer of the dimeric complex of cytochrome b 6 f is comprised of eight subunits that are both nucleus- and plastid-encoded. Proper cytochrome b 6 f complex integration into the thylakoid membrane requires numerous regulatory factors for coordinated transport, insertion and assembly of the subunits. Although, the chloroplast-encoded cytochrome b 6 f subunit IV (PetD) consists of three transmembrane helices, the signal and the mechanism of protein integration into the thylakoid membrane have not been identified. RESULTS Here, we demonstrate that the native PetD subunit cannot incorporate into the thylakoid membranes spontaneously, but that proper integration occurs through the post-translational signal recognition particle (SRP) pathway. Furthermore, we show that PetD insertion into thylakoid membrane involves the coordinated action of cpFTSY, cpSRP54 and ALB3 insertase. CONCLUSIONS PetD subunit integration into the thylakoid membrane is a post-translational and an SRP-dependent process that requires the formation of the cpSRP-cpFtsY-ALB3-PetD complex. This data provides a new insight into the molecular mechanisms by which membrane proteins integration into the thylakoid membrane is accomplished and is not limited to PetD.
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Affiliation(s)
- Jarosław Króliczewski
- Faculty of Biotechnology, University of Wrocław, Fryderyka Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Rafał Bartoszewski
- Department of Biology and Pharmaceutical Botany Medical University of Gdańsk, Hallera 107, 80-416 Gdansk, Poland
| | - Bożena Króliczewska
- Department of Animal Physiology and Biostructure, Faculty of Veterinary Medicine Wroclaw University of Environmental and Life Sciences, C.K Norwida 31, 50-375 Wrocław, Poland
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8
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Ziehe D, Dünschede B, Schünemann D. From bacteria to chloroplasts: evolution of the chloroplast SRP system. Biol Chem 2017; 398:653-661. [PMID: 28076289 DOI: 10.1515/hsz-2016-0292] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 01/04/2017] [Indexed: 02/02/2023]
Abstract
Chloroplasts derive from a prokaryotic symbiont that lost most of its genes during evolution. As a result, the great majority of chloroplast proteins are encoded in the nucleus and are posttranslationally imported into the organelle. The chloroplast genome encodes only a few proteins. These include several multispan thylakoid membrane proteins which are synthesized on thylakoid-bound ribosomes and cotranslationally inserted into the membrane. During evolution, ancient prokaryotic targeting machineries were adapted and combined with novel targeting mechanisms to facilitate post- and cotranslational protein transport in chloroplasts. This review focusses on the chloroplast signal recognition particle (cpSRP) protein transport system, which has been intensively studied in higher plants. The cpSRP system derived from the prokaryotic SRP pathway, which mediates the cotranslational protein transport to the bacterial plasma membrane. Chloroplasts contain homologs of several components of the bacterial SRP system. The function of these conserved components in post- and/or cotranslational protein transport and chloroplast-specific modifications of these transport mechanisms are described. Furthermore, recent studies of cpSRP systems in algae and lower plants are summarized and their impact on understanding the evolution of the cpSRP system are discussed.
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Affiliation(s)
- Dominik Ziehe
- Molecular Biology of Plant Organelles, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum
| | - Beatrix Dünschede
- Molecular Biology of Plant Organelles, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum
| | - Danja Schünemann
- Molecular Biology of Plant Organelles, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum
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Jeong J, Baek K, Kirst H, Melis A, Jin E. Loss of CpSRP54 function leads to a truncated light-harvesting antenna size in Chlamydomonas reinhardtii. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:45-55. [DOI: 10.1016/j.bbabio.2016.10.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 10/14/2016] [Accepted: 10/14/2016] [Indexed: 10/20/2022]
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10
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Bieri P, Leibundgut M, Saurer M, Boehringer D, Ban N. The complete structure of the chloroplast 70S ribosome in complex with translation factor pY. EMBO J 2016; 36:475-486. [PMID: 28007896 PMCID: PMC5694952 DOI: 10.15252/embj.201695959] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 11/24/2016] [Accepted: 11/28/2016] [Indexed: 01/21/2023] Open
Abstract
Chloroplasts are cellular organelles of plants and algae that are responsible for energy conversion and carbon fixation by the photosynthetic reaction. As a consequence of their endosymbiotic origin, they still contain their own genome and the machinery for protein biosynthesis. Here, we present the atomic structure of the chloroplast 70S ribosome prepared from spinach leaves and resolved by cryo‐EM at 3.4 Å resolution. The complete structure reveals the features of the 4.5S rRNA, which probably evolved by the fragmentation of the 23S rRNA, and all five plastid‐specific ribosomal proteins. These proteins, required for proper assembly and function of the chloroplast translation machinery, bind and stabilize rRNA including regions that only exist in the chloroplast ribosome. Furthermore, the structure reveals plastid‐specific extensions of ribosomal proteins that extensively remodel the mRNA entry and exit site on the small subunit as well as the polypeptide tunnel exit and the putative binding site of the signal recognition particle on the large subunit. The translation factor pY, involved in light‐ and temperature‐dependent control of protein synthesis, is bound to the mRNA channel of the small subunit and interacts with 16S rRNA nucleotides at the A‐site and P‐site, where it protects the decoding centre and inhibits translation by preventing tRNA binding. The small subunit is locked by pY in a non‐rotated state, in which the intersubunit bridges to the large subunit are stabilized.
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Affiliation(s)
- Philipp Bieri
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Marc Leibundgut
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Martin Saurer
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Daniel Boehringer
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
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Chandrasekar S, Shan SO. Anionic Phospholipids and the Albino3 Translocase Activate Signal Recognition Particle-Receptor Interaction during Light-harvesting Chlorophyll a/b-binding Protein Targeting. J Biol Chem 2016; 292:397-406. [PMID: 27895124 DOI: 10.1074/jbc.m116.752956] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/14/2016] [Indexed: 01/12/2023] Open
Abstract
The universally conserved signal recognition particle (SRP) co-translationally delivers newly synthesized membrane and secretory proteins to the target cellular membrane. The only exception is found in the chloroplast of green plants, where the chloroplast SRP (cpSRP) post-translationally targets light-harvesting chlorophyll a/b-binding proteins (LHCP) to the thylakoid membrane. The mechanism and regulation of this post-translational mode of targeting by cpSRP remain unclear. Using biochemical and biophysical methods, here we show that anionic phospholipids activate the cpSRP receptor cpFtsY to promote rapid and stable cpSRP54·cpFtsY complex assembly. Furthermore, the stromal domain of the Alb3 translocase binds with high affinity to and regulates GTP hydrolysis in the cpSRP54·cpFtsY complex, suggesting that cpFtsY is primarily responsible for initial recruitment of the targeting complex to Alb3. These results suggest a new model for the sequential recruitment, remodeling, and unloading of the targeting complex at membrane translocase sites in the post-translational cpSRP pathway.
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Affiliation(s)
- Sowmya Chandrasekar
- From the Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - Shu-Ou Shan
- From the Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
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Ziehe D, Dünschede B, Zenker M, Funke S, Nowaczyk MM, Schünemann D. The Chloroplast SRP Systems of Chaetosphaeridium globosum and Physcomitrella patens as Intermediates in the Evolution of SRP-Dependent Protein Transport in Higher Plants. PLoS One 2016; 11:e0166818. [PMID: 27861610 PMCID: PMC5115805 DOI: 10.1371/journal.pone.0166818] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/05/2016] [Indexed: 11/19/2022] Open
Abstract
The bacterial signal recognition particle (SRP) mediates the cotranslational targeting of membrane proteins and is a high affinity complex consisting of a SRP54 protein subunit (Ffh) and an SRP RNA. The chloroplast SRP (cpSRP) pathway has adapted throughout evolution to enable the posttranslational targeting of the light harvesting chlorophyll a/b binding proteins (LHCPs) to the thylakoid membrane. In spermatophytes (seed plants), the cpSRP lacks the SRP RNA and is instead formed by a high affinity interaction of the conserved 54-kD subunit (cpSRP54) with the chloroplast-specific cpSRP43 protein. This heterodimeric cpSRP recognizes LHCP and delivers it to the thylakoid membrane. However, in contrast to spermatophytes, plastid SRP RNAs were identified within all streptophyte lineages and in all chlorophyte branches. Furthermore, it was shown that cpSRP43 does not interact with cpSRP54 in chlorophytes (e.g., Chlamydomonas reinhardtii). In this study, we biochemically characterized the cpSRP system of the charophyte Chaetosphaeridium globosum and the bryophyte Physcomitrella patens. Interaction studies demonstrate low affinity binding of cpSRP54 to cpSRP43 (Kd ~10 μM) in Chaetosphaeridium globosum and Physcomitrella patens as well as relatively low affinity binding of cpSRP54 to cpSRP RNA (Kd ~1 μM) in Physcomitrella patens. CpSRP54/cpSRP43 complex formation in charophytes is supported by the finding that specific alterations in the second chromodomain of cpSRP43, that are conserved within charophytes and absent in land plants, do not interfere with cpSRP54 binding. Furthermore, our data show that the elongated apical loop structure of the Physcomitrella patens cpSRP RNA contributes to the low binding affinity between cpSRP54 and the cpSRP RNA.
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Affiliation(s)
- Dominik Ziehe
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Beatrix Dünschede
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Mira Zenker
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Silke Funke
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Marc M. Nowaczyk
- Cyanobacterial Membrane Protein Complexes, Ruhr-University Bochum, 44780, Bochum, Germany
| | - Danja Schünemann
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780, Bochum, Germany
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13
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Henderson RC, Gao F, Jayanthi S, Kight A, Sharma P, Goforth RL, Heyes CD, Henry RL, Suresh Kumar TK. Domain Organization in the 54-kDa Subunit of the Chloroplast Signal Recognition Particle. Biophys J 2016; 111:1151-1162. [PMID: 27653474 PMCID: PMC5034345 DOI: 10.1016/j.bpj.2016.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 07/29/2016] [Accepted: 08/02/2016] [Indexed: 10/21/2022] Open
Abstract
Chloroplast signal recognition particle (cpSRP) is a heterodimer composed of an evolutionarily conserved 54-kDa GTPase (cpSRP54) and a unique 43-kDa subunit (cpSRP43) responsible for delivering light-harvesting chlorophyll binding protein to the thylakoid membrane. While a nearly complete three-dimensional structure of cpSRP43 has been determined, no high-resolution structure is yet available for cpSRP54. In this study, we developed and examined an in silico three-dimensional model of the structure of cpSRP54 by homology modeling using cytosolic homologs. Model selection was guided by single-molecule Förster resonance energy transfer experiments, which revealed the presence of at least two distinct conformations. Small angle x-ray scattering showed that the linking region among the GTPase (G-domain) and methionine-rich (M-domain) domains, an M-domain loop, and the cpSRP43 binding C-terminal extension of cpSRP54 are predominantly disordered. Interestingly, the linker and loop segments were observed to play an important role in organizing the domain arrangement of cpSRP54. Further, deletion of the finger loop abolished loading of the cpSRP cargo, light-harvesting chlorophyll binding protein. These data highlight important structural dynamics relevant to cpSRP54's role in the post- and cotranslational signaling processes.
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Affiliation(s)
- Rory C Henderson
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas
| | - Feng Gao
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas
| | - Srinivas Jayanthi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas
| | - Alicia Kight
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas
| | - Priyanka Sharma
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas
| | - Robyn L Goforth
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas
| | - Colin D Heyes
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas
| | - Ralph L Henry
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas
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Nymark M, Sharma AK, Sparstad T, Bones AM, Winge P. A CRISPR/Cas9 system adapted for gene editing in marine algae. Sci Rep 2016; 6:24951. [PMID: 27108533 PMCID: PMC4842962 DOI: 10.1038/srep24951] [Citation(s) in RCA: 207] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 04/07/2016] [Indexed: 12/15/2022] Open
Abstract
Here we report that the CRISPR/Cas9 technology can be used to efficiently generate stable targeted gene mutations in microalgae, using the marine diatom Phaeodactylum tricornutum as a model species. Our vector design opens for rapid and easy adaption of the construct to the target chosen. To screen for CRISPR/Cas9 mutants we employed high resolution melting based PCR assays, mutants were confirmed by sequencing and further validated by functional analyses.
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Affiliation(s)
- Marianne Nymark
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Amit Kumar Sharma
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Torfinn Sparstad
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Atle M Bones
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Per Winge
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
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15
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Wang P, Grimm B. Organization of chlorophyll biosynthesis and insertion of chlorophyll into the chlorophyll-binding proteins in chloroplasts. PHOTOSYNTHESIS RESEARCH 2015; 126:189-202. [PMID: 25957270 DOI: 10.1007/s11120-015-0154-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/30/2015] [Indexed: 05/23/2023]
Abstract
Oxygenic photosynthesis requires chlorophyll (Chl) for the absorption of light energy, and charge separation in the reaction center of photosystem I and II, to feed electrons into the photosynthetic electron transfer chain. Chl is bound to different Chl-binding proteins assembled in the core complexes of the two photosystems and their peripheral light-harvesting antenna complexes. The structure of the photosynthetic protein complexes has been elucidated, but mechanisms of their biogenesis are in most instances unknown. These processes involve not only the assembly of interacting proteins, but also the functional integration of pigments and other cofactors. As a precondition for the association of Chl with the Chl-binding proteins in both photosystems, the synthesis of the apoproteins is synchronized with Chl biosynthesis. This review aims to summarize the present knowledge on the posttranslational organization of Chl biosynthesis and current attempts to envision the proceedings of the successive synthesis and integration of Chl into Chl-binding proteins in the thylakoid membrane. Potential auxiliary factors, contributing to the control and organization of Chl biosynthesis and the association of Chl with the Chl-binding proteins during their integration into photosynthetic complexes, are discussed in this review.
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Affiliation(s)
- Peng Wang
- Institute of Biology/Plant Physiology, Humboldt-University Berlin, Philippstraße 13, 10115, Berlin, Germany
| | - Bernhard Grimm
- Institute of Biology/Plant Physiology, Humboldt-University Berlin, Philippstraße 13, 10115, Berlin, Germany.
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16
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Breiman A, Fieulaine S, Meinnel T, Giglione C. The intriguing realm of protein biogenesis: Facing the green co-translational protein maturation networks. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1864:531-50. [PMID: 26555180 DOI: 10.1016/j.bbapap.2015.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/05/2015] [Indexed: 01/13/2023]
Abstract
The ribosome is the cell's protein-making factory, a huge protein-RNA complex, that is essential to life. Determining the high-resolution structures of the stable "core" of this factory was among the major breakthroughs of the past decades, and was awarded the Nobel Prize in 2009. Now that the mysteries of the ribosome appear to be more traceable, detailed understanding of the mechanisms that regulate protein synthesis includes not only the well-known steps of initiation, elongation, and termination but also the less comprehended features of the co-translational events associated with the maturation of the nascent chains. The ribosome is a platform for co-translational events affecting the nascent polypeptide, including protein modifications, folding, targeting to various cellular compartments for integration into membrane or translocation, and proteolysis. These events are orchestrated by ribosome-associated protein biogenesis factors (RPBs), a group of a dozen or more factors that act as the "welcoming committee" for the nascent chain as it emerges from the ribosome. In plants these factors have evolved to fit the specificity of different cellular compartments: cytoplasm, mitochondria and chloroplast. This review focuses on the current state of knowledge of these factors and their interaction around the exit tunnel of dedicated ribosomes. Particular attention has been accorded to the plant system, highlighting the similarities and differences with other organisms.
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Affiliation(s)
- Adina Breiman
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Univ. Paris-Saclay 91198 Gif-sur-Yvette cedex, France; Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel
| | - Sonia Fieulaine
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Univ. Paris-Saclay 91198 Gif-sur-Yvette cedex, France
| | - Thierry Meinnel
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Univ. Paris-Saclay 91198 Gif-sur-Yvette cedex, France
| | - Carmela Giglione
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Univ. Paris-Saclay 91198 Gif-sur-Yvette cedex, France.
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17
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Walter B, Hristou A, Nowaczyk MM, Schünemann D. In vitro reconstitution of co-translational D1 insertion reveals a role of the cpSec-Alb3 translocase and Vipp1 in photosystem II biogenesis. Biochem J 2015; 468:315-24. [PMID: 25803492 DOI: 10.1042/bj20141425] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Photosystem II (PS II) is a multi-subunit complex localized in the thylakoid membrane that performs the light-dependent photosynthetic charge separation. The PS II reaction centre comprises, among others, the D1 protein. De novo synthesis and repair of PS II require efficient mechanisms for transport and insertion of plastid encoded D1 into the thylakoid membrane. To elucidate the process of D1 insertion, we used an in vitro translation system derived from pea chloroplasts to reconstitute the D1 insertion. Thereby, truncated D1 encoding psbA mRNAs lacking a stop codon were translated in the presence of thylakoid membranes and the translation was stalled by addition of chloramphenicol. The generated ribosome nascent chain complexes (RNCs) were tightly associated with the thylakoids. Subsequently, these D1 insertion intermediates were enriched from solubilized thylakoids by sucrose cushion centrifugation. Immunological analyses demonstrated the presence of the cpSec translocase, Alb3, cpFtsY, cpSRP54 and Vipp1 (vesicle-inducing protein in plastids 1) in the enriched D1 insertion intermediates. A complex formation between cpSecY, Alb3, cpFtsY and Vipp1 in thylakoid membranes was shown by gel filtration chromatography, BN (Blue Native)/SDS-PAGE and co-immunoprecipitation experiments. Furthermore, a stimulating effect of recombinant Vipp1 on the formation of a D1 insertion intermediate was observed in vitro. These results suggest a co-operative function of these proteins in D1 insertion.
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Affiliation(s)
- Björn Walter
- *Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Athina Hristou
- *Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Marc M Nowaczyk
- †Plant Biochemistry, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Danja Schünemann
- *Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780 Bochum, Germany
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18
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Schöttler MA, Tóth SZ, Boulouis A, Kahlau S. Photosynthetic complex stoichiometry dynamics in higher plants: biogenesis, function, and turnover of ATP synthase and the cytochrome b6f complex. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2373-400. [PMID: 25540437 DOI: 10.1093/jxb/eru495] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
During plant development and in response to fluctuating environmental conditions, large changes in leaf assimilation capacity and in the metabolic consumption of ATP and NADPH produced by the photosynthetic apparatus can occur. To minimize cytotoxic side reactions, such as the production of reactive oxygen species, photosynthetic electron transport needs to be adjusted to the metabolic demand. The cytochrome b6f complex and chloroplast ATP synthase form the predominant sites of photosynthetic flux control. Accordingly, both respond strongly to changing environmental conditions and metabolic states. Usually, their contents are strictly co-regulated. Thereby, the capacity for proton influx into the lumen, which is controlled by electron flux through the cytochrome b6f complex, is balanced with proton efflux through ATP synthase, which drives ATP synthesis. We discuss the environmental, systemic, and metabolic signals triggering the stoichiometry adjustments of ATP synthase and the cytochrome b6f complex. The contribution of transcriptional and post-transcriptional regulation of subunit synthesis, and the importance of auxiliary proteins required for complex assembly in achieving the stoichiometry adjustments is described. Finally, current knowledge on the stability and turnover of both complexes is summarized.
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Affiliation(s)
- Mark Aurel Schöttler
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Szilvia Z Tóth
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Alix Boulouis
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Sabine Kahlau
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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19
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Walter B, Pieta T, Schünemann D. Arabidopsis thaliana mutants lacking cpFtsY or cpSRP54 exhibit different defects in photosystem II repair. FRONTIERS IN PLANT SCIENCE 2015; 6:250. [PMID: 25918516 PMCID: PMC4394663 DOI: 10.3389/fpls.2015.00250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/27/2015] [Indexed: 05/24/2023]
Abstract
Photosystem II (PS II) is a multi subunit protein complex embedded in the thylakoid membrane of cyanobacteria and chloroplasts. As the PS II reaction center protein D1 is prone to a light induced damage that inhibits PS II function especially at elevated light intensities, a highly ordered repair process including synthesis, targeting and insertion of D1 has evolved. To elucidate the function of the chloroplast signal recognition particle subunits, cpSRP43 and cpSRP54, and the cpSRP-receptor cpFtsY in D1 biogenesis we investigated the efficiency of the PS II repair cycle in the corresponding mutants of Arabidopsis thaliana. Immunological analyses, PAM measurements and in vivo labeling experiments demonstrate an impaired replacement of damaged D1 in the cpftsy mutant, while the chaos and the ffc mutant lacking cpSRP43 and cpSRP54, respectively, were not or hardly affected. The defect in cpftsy was neither caused by an impaired psbA transcript accumulation, D1 translation initiation nor by an enhanced D1 degradation. Further experiments revealed a decreased amount of salt stable, thylakoid membrane-associated translating ribosomes in the cpftsy mutant, while the amount of membrane-associated translating ribosomes is unaltered in the chaos and the ffc mutants. Therefore, our data indicate that the lack of cpFtsY leads to an inefficient PS II repair cycle caused by an impaired binding of translating ribosomes to the thylakoid membrane.
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Affiliation(s)
- Björn Walter
- Molecular Biology of Plant Organelles, Ruhr-University BochumBochum, Germany
| | - Thomas Pieta
- Plant Cell Physiology and Molecular Biology, Ruhr-University BochumBochum, Germany
| | - Danja Schünemann
- Molecular Biology of Plant Organelles, Ruhr-University BochumBochum, Germany
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20
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Dünschede B, Träger C, Schröder CV, Ziehe D, Walter B, Funke S, Hofmann E, Schünemann D. Chloroplast SRP54 Was Recruited for Posttranslational Protein Transport via Complex Formation with Chloroplast SRP43 during Land Plant Evolution. J Biol Chem 2015; 290:13104-14. [PMID: 25833951 DOI: 10.1074/jbc.m114.597922] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Indexed: 01/05/2023] Open
Abstract
In bacteria, membrane proteins are targeted cotranslationally via a signal recognition particle (SRP). During the evolution of higher plant chloroplasts from cyanobacteria, the SRP pathway underwent striking adaptations that enable the posttranslational transport of the abundant light-harvesting chlorophyll-a/b-binding proteins (LHCPs). The conserved 54-kDa SRP subunit in higher plant chloroplasts (cpSRP54) is not bound to an SRP RNA, an essential SRP component in bacteria, but forms a stable heterodimer with the chloroplast-specific cpSRP43. This heterodimeric cpSRP recognizes LHCP and delivers it to the thylakoid membrane whereby cpSRP43 plays a central role. This study shows that the cpSRP system in the green alga Chlamydomonas reinhardtii differs significantly from that of higher plants as cpSRP43 is not complexed to cpSRP54 in Chlamydomonas and cpSRP54 is not involved in LHCP recognition. This divergence is attributed to altered residues within the cpSRP54 tail and the second chromodomain of cpSRP43 that are crucial for the formation of the binding interface in Arabidopsis. These changes are highly conserved among chlorophytes, whereas all land plants contain cpSRP proteins with typical interaction motifs. These data demonstrate that the coevolution of LHCPs and cpSRP43 occurred independently of complex formation with cpSRP54 and that the interaction between cpSRP54 and cpSRP43 evolved later during the transition from chlorophytes to land plants. Furthermore, our data show that in higher plants a heterodimeric form of cpSRP is required for the formation of a low molecular weight transit complex with LHCP.
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Affiliation(s)
| | | | | | | | - Björn Walter
- From the Molecular Biology of Plant Organelles and
| | - Silke Funke
- From the Molecular Biology of Plant Organelles and
| | - Eckhard Hofmann
- Protein Crystallography, Ruhr University Bochum, 44780 Bochum, Germany
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21
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Guo P, Qi YP, Yang LT, Ye X, Jiang HX, Huang JH, Chen LS. cDNA-AFLP analysis reveals the adaptive responses of citrus to long-term boron-toxicity. BMC PLANT BIOLOGY 2014; 14:284. [PMID: 25348611 PMCID: PMC4219002 DOI: 10.1186/s12870-014-0284-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Accepted: 10/14/2014] [Indexed: 05/02/2023]
Abstract
BACKGROUND Boron (B)-toxicity is an important disorder in agricultural regions across the world. Seedlings of 'Sour pummelo' (Citrus grandis) and 'Xuegan' (Citrus sinensis) were fertigated every other day until drip with 10 μM (control) or 400 μM (B-toxic) H3BO3 in a complete nutrient solution for 15 weeks. The aims of this study were to elucidate the adaptive mechanisms of citrus plants to B-toxicity and to identify B-tolerant genes. RESULTS B-toxicity-induced changes in seedlings growth, leaf CO2 assimilation, pigments, total soluble protein, malondialdehyde (MDA) and phosphorus were less pronounced in C. sinensis than in C. grandis. B concentration was higher in B-toxic C. sinensis leaves than in B-toxic C. grandis ones. Here we successfully used cDNA-AFLP to isolate 67 up-regulated and 65 down-regulated transcript-derived fragments (TDFs) from B-toxic C. grandis leaves, whilst only 31 up-regulated and 37 down-regulated TDFs from B-toxic C. sinensis ones, demonstrating that gene expression is less affected in B-toxic C. sinensis leaves than in B-toxic C. grandis ones. These differentially expressed TDFs were related to signal transduction, carbohydrate and energy metabolism, nucleic acid metabolism, protein and amino acid metabolism, lipid metabolism, cell wall and cytoskeleton modification, stress responses and cell transport. The higher B-tolerance of C. sinensis might be related to the findings that B-toxic C. sinensis leaves had higher expression levels of genes involved in photosynthesis, which might contribute to the higher photosyntheis and light utilization and less excess light energy, and in reactive oxygen species (ROS) scavenging compared to B-toxic C. grandis leaves, thus preventing them from photo-oxidative damage. In addition, B-toxicity-induced alteration in the expression levels of genes encoding inorganic pyrophosphatase 1, AT4G01850 and methionine synthase differed between the two species, which might play a role in the B-tolerance of C. sinensis. CONCLUSIONS C. sinensis leaves could tolerate higher level of B than C. grandis ones, thus improving the B-tolerance of C. sinensis plants. Our findings reveal some novel mechanisms on the tolerance of plants to B-toxicity at the gene expression level.
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Affiliation(s)
- Peng Guo
- />College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- />Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Yi-Ping Qi
- />Institute of Materia Medica, Fujian Academy of Medical Sciences, Fuzhou, 350001 China
| | - Lin-Tong Yang
- />College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- />Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Xin Ye
- />College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Huan-Xin Jiang
- />Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- />College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Jing-Hao Huang
- />Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- />College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- />Institute of Fruit Tree Science, Fujian Academy of Agricultural Sciences, Fuzhou, 350013 China
| | - Li-Song Chen
- />College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- />Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- />Fujian Key Laboratory for Plant Molecular and Cell Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- />The Higher Educational Key Laboratory of Fujian Province for Soil Ecosystem Health and Regulation, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
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22
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The chloroplast signal recognition particle (CpSRP) pathway as a tool to minimize chlorophyll antenna size and maximize photosynthetic productivity. Biotechnol Adv 2014; 32:66-72. [DOI: 10.1016/j.biotechadv.2013.08.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/28/2013] [Accepted: 08/29/2013] [Indexed: 11/21/2022]
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23
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Rosenblad MA, Träger C, Träger C, Schünemann D, Schünemann D. Structural diversity of signal recognition particle RNAs in plastids. PLANT SIGNALING & BEHAVIOR 2013; 8:doi: 10.4161/psb.26848. [PMID: 24494244 PMCID: PMC4091067 DOI: 10.4161/psb.26848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 10/17/2013] [Indexed: 06/03/2023]
Abstract
One of the pathways for protein targeting to the plasma membrane in bacteria utilizes the co-translationally acting signal recognition particle (SRP), a universally conserved ribonucleoprotein complex consisting of a 54 kDa protein and a functional RNA. An interesting exception is the higher plant chloroplast SRP, which lacks the otherwise essential RNA component. Furthermore, green plant chloroplasts have an additional post-translational SRP-dependent transport system in which the chloroplast-specific cpSRP43 protein binds to imported substrate proteins and to the conserved 54 kDa SRP subunit (cpSRP54). While homologs to the bacterial SRP protein and RNA component previously have been identified in genome sequences of red algae and diatoms, a recent study investigated the evolution of the green plant SRP system.1 Analysis of hundreds of plastid and nuclear genomes showed a surprising pattern of multiple losses of the plastid SRP RNA during evolution and a widespread presence in all non-spermatophyte plants and green algae. Contrary to expectations, all green organisms that have an identified cpSRP RNA also contain a cpSRP43. Notably, the structure of the plastid SRP RNAs is much more diverse than that of bacterial SRP RNAs. The apical GNRA tetraloop is only conserved in organisms of the red lineage and basal organisms of the green lineage, whereas further chloroplast SRP RNAs are characterized by atypical, mostly enlarged apical loops.
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Affiliation(s)
- Magnus Alm Rosenblad
- Department of Chemistry and Molecular Biology; University of Gothenburg; Gothenburg, Sweden
| | - Chantal Träger
- Molecular Biology of Plant Organelles; Ruhr-University Bochum; Bochum, Germany
| | - Chantal Träger
- Molecular Biology of Plant Organelles; Ruhr-University Bochum; Bochum, Germany
| | - Danja Schünemann
- Molecular Biology of Plant Organelles; Ruhr-University Bochum; Bochum, Germany
| | - Danja Schünemann
- Molecular Biology of Plant Organelles; Ruhr-University Bochum; Bochum, Germany
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24
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Zhang F, Luo X, Hu B, Wan Y, Xie J. YGL138(t), encoding a putative signal recognition particle 54 kDa protein, is involved in chloroplast development of rice. RICE (NEW YORK, N.Y.) 2013; 6:7. [PMID: 24280537 PMCID: PMC4883693 DOI: 10.1186/1939-8433-6-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 03/20/2013] [Indexed: 05/18/2023]
Abstract
BACKGROUND Normal development of chloroplast is vitally important to plants, but its biological mechanism is still far from fully being understood, especially in rice. RESULTS In this study, a novel yellow-green leaf mutant, ygl138, derived from Nipponbare (Oryza sativa L. ssp. japonica) treated by ethyl methanesulfonate (EMS), was isolated. The mutant exhibited a distinct yellow-green leaf phenotype throughout development, reduced chlorophyll level, and arrested chloroplast development. The phenotype of the ygl138 mutant was caused by a single nuclear gene, which was tentatively designed as YGL138(t). The YGL138(t) locus was mapped to chromosome 11 and isolated into a confined region of 91.8 kb by map-based cloning. Sequencing analysis revealed that, Os11g05552, which was predicted to encode a signal recognition particle 54 kDa (SRP54) protein and act as a chloroplast precursor, had 18 bp nucleotides deletion in the coding region of ygl138 and led to a frameshift. Furthermore, the identity of Os11g05552 was verified by transgenic complementation. CONCLUSIONS These results are very valuable for further study on YGL138(t) gene and illuminating the mechanism of SRP54 protein involving in chloroplast development of rice.
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Affiliation(s)
- Fantao Zhang
- />College of Life Sciences, Jiangxi Normal University, Nanchang, 330022 China
| | - Xiangdong Luo
- />College of Life Sciences, Jiangxi Normal University, Nanchang, 330022 China
| | - Biaolin Hu
- />Biotechnology Research Institute, Jiangxi Academy of Agricultural Sciences, Nanchang, 330200 China
| | - Yong Wan
- />Biotechnology Research Institute, Jiangxi Academy of Agricultural Sciences, Nanchang, 330200 China
| | - Jiankun Xie
- />College of Life Sciences, Jiangxi Normal University, Nanchang, 330022 China
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25
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Abstract
The signal recognition particle (SRP) and its receptor compose a universally conserved and essential cellular machinery that couples the synthesis of nascent proteins to their proper membrane localization. The past decade has witnessed an explosion in in-depth mechanistic investigations of this targeting machine at increasingly higher resolutions. In this review, we summarize recent work that elucidates how the SRP and SRP receptor interact with the cargo protein and the target membrane, respectively, and how these interactions are coupled to a novel GTPase cycle in the SRP·SRP receptor complex to provide the driving force and enhance the fidelity of this fundamental cellular pathway. We also discuss emerging frontiers in which important questions remain to be addressed.
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Affiliation(s)
- David Akopian
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Kuang Shen
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Xin Zhang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Shu-ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
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26
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Benz M, Soll J, Ankele E. Arabidopsis thaliana Oxa proteins locate to mitochondria and fulfill essential roles during embryo development. PLANTA 2013; 237:573-88. [PMID: 23179441 DOI: 10.1007/s00425-012-1793-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 10/19/2012] [Indexed: 05/12/2023]
Abstract
Members of the Alb3/Oxa1/YidC protein family function as insertases in chloroplasts, mitochondria, and bacteria. Due to independent gene duplications, all organisms possess two isoforms, Oxa1 and Oxa2 except gram-negative bacteria, which encode only for one YidC-like protein. The genome of Arabidopsis thaliana however, encodes for eight different isoforms. The localization of three of these isoforms has been identified earlier: Alb3 and Alb4 located in thylakoid membranes of chloroplasts while AtOxa1 was found in the inner membrane of mitochondria. Here, we show that the second Oxa1 protein, Oxa1b as well as two Oxa2 proteins are also localized in mitochondria. The last two isoforms most likely encode truncated versions of Oxa-like proteins, which might be inoperable pseudogenes. Homozygous mutant lines were only obtained for Oxa1b, which did not reveal any significant phenotypes, while T-DNA insertion lines of Oxa1a, Oxa2a and Oxa2b resulted only in heterozygous plants indicating that these genes are indispensable for plant development. Phenotyping heterozygous lines showed that embryos are either retarded in growth, display an albino phenotype or embryo formation was entirely abolished suggesting that Oxa1a and both Oxa2 proteins function in embryo formation although at different developmental stages as indicated by the various phenotypes observed.
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Affiliation(s)
- Monique Benz
- Energy Biosciences Institute, University of California, 2151 Berkeley Way, Berkeley, CA 94720-5230, USA.
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27
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Meierhoff K, Westhoff P. The Biogenesis of the Thylakoid Membrane: Photosystem II, a Case Study. PLASTID DEVELOPMENT IN LEAVES DURING GROWTH AND SENESCENCE 2013. [DOI: 10.1007/978-94-007-5724-0_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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28
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Huang M, Friso G, Nishimura K, Qu X, Olinares PDB, Majeran W, Sun Q, van Wijk KJ. Construction of Plastid Reference Proteomes for Maize and Arabidopsis and Evaluation of Their Orthologous Relationships; The Concept of Orthoproteomics. J Proteome Res 2012. [DOI: 10.1021/pr300952g] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mingshu Huang
- Department
of Plant Biology and ‡Computational Biology Service Unit, Cornell University, Ithaca, New York 14853, United States
| | - Giulia Friso
- Department
of Plant Biology and ‡Computational Biology Service Unit, Cornell University, Ithaca, New York 14853, United States
| | - Kenji Nishimura
- Department
of Plant Biology and ‡Computational Biology Service Unit, Cornell University, Ithaca, New York 14853, United States
| | - Xian Qu
- Department
of Plant Biology and ‡Computational Biology Service Unit, Cornell University, Ithaca, New York 14853, United States
| | - Paul Dominic B. Olinares
- Department
of Plant Biology and ‡Computational Biology Service Unit, Cornell University, Ithaca, New York 14853, United States
| | - Wojciech Majeran
- Department
of Plant Biology and ‡Computational Biology Service Unit, Cornell University, Ithaca, New York 14853, United States
| | - Qi Sun
- Department
of Plant Biology and ‡Computational Biology Service Unit, Cornell University, Ithaca, New York 14853, United States
| | - Klaas J. van Wijk
- Department
of Plant Biology and ‡Computational Biology Service Unit, Cornell University, Ithaca, New York 14853, United States
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Steiner JM, Bhattacharya D, Löffelhardt W. Conservative sorting in the muroplasts of Cyanophora paradoxa: a reevaluation based on the completed genome sequence. Symbiosis 2012. [DOI: 10.1007/s13199-012-0203-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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30
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Träger C, Rosenblad MA, Ziehe D, Garcia-Petit C, Schrader L, Kock K, Vera Richter C, Klinkert B, Narberhaus F, Herrmann C, Hofmann E, Aronsson H, Schünemann D. Evolution from the prokaryotic to the higher plant chloroplast signal recognition particle: the signal recognition particle RNA is conserved in plastids of a wide range of photosynthetic organisms. THE PLANT CELL 2012; 24:4819-36. [PMID: 23275580 PMCID: PMC3556960 DOI: 10.1105/tpc.112.102996] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The protein targeting signal recognition particle (SRP) pathway in chloroplasts of higher plants has undergone dramatic evolutionary changes. It disposed of its RNA, which is an essential SRP component in bacteria, and uses a unique chloroplast-specific protein cpSRP43. Nevertheless, homologs of the conserved SRP54 and the SRP receptor, FtsY, are present in higher plant chloroplasts. In this study, we analyzed the phylogenetic distribution of SRP components in photosynthetic organisms to elucidate the evolution of the SRP system. We identified conserved plastid SRP RNAs within all nonspermatophyte land plant lineages and in all chlorophyte branches. Furthermore, we show the simultaneous presence of cpSRP43 in these organisms. The function of this novel SRP system was biochemically and structurally characterized in the moss Physcomitrella patens. We show that P. patens chloroplast SRP (cpSRP) RNA binds cpSRP54 but has lost the ability to significantly stimulate the GTPase cycle of SRP54 and FtsY. Furthermore, the crystal structure at 1.8-Å resolution and the nucleotide specificity of P. patens cpFtsY was determined and compared with bacterial FtsY and higher plant chloroplast FtsY. Our data lead to the view that the P. patens cpSRP system occupies an intermediate position in the evolution from bacterial-type SRP to higher plant-type cpSRP system.
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Affiliation(s)
- Chantal Träger
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Magnus Alm Rosenblad
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Dominik Ziehe
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Christel Garcia-Petit
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Lukas Schrader
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Klaus Kock
- Physical Chemistry I, Ruhr-University Bochum, 44780 Bochum, Germany
| | | | - Birgit Klinkert
- Microbial Biology, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Franz Narberhaus
- Microbial Biology, Ruhr-University Bochum, 44780 Bochum, Germany
| | | | - Eckhard Hofmann
- Protein Crystallography, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Henrik Aronsson
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Danja Schünemann
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780 Bochum, Germany
- Address correspondence to
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31
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Albus CA, Salinas A, Czarnecki O, Kahlau S, Rothbart M, Thiele W, Lein W, Bock R, Grimm B, Schöttler MA. LCAA, a novel factor required for magnesium protoporphyrin monomethylester cyclase accumulation and feedback control of aminolevulinic acid biosynthesis in tobacco. PLANT PHYSIOLOGY 2012; 160:1923-39. [PMID: 23085838 PMCID: PMC3510121 DOI: 10.1104/pp.112.206045] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 10/18/2012] [Indexed: 05/03/2023]
Abstract
Low Chlorophyll Accumulation A (LCAA) antisense plants were obtained from a screen for genes whose partial down-regulation results in a strong chlorophyll deficiency in tobacco (Nicotiana tabacum). The LCAA mutants are affected in a plastid-localized protein of unknown function, which is conserved in cyanobacteria and all photosynthetic eukaryotes. They suffer from drastically reduced light-harvesting complex (LHC) contents, while the accumulation of all other photosynthetic complexes per leaf area is less affected. As the disturbed accumulation of LHC proteins could be either attributable to a defect in LHC biogenesis itself or to a bottleneck in chlorophyll biosynthesis, chlorophyll synthesis rates and chlorophyll synthesis intermediates were measured. LCAA antisense plants accumulate magnesium (Mg) protoporphyrin monomethylester and contain reduced protochlorophyllide levels and a reduced content of CHL27, a subunit of the Mg protoporphyrin monomethylester cyclase. Bimolecular fluorescence complementation assays confirm a direct interaction between LCAA and CHL27. 5-Aminolevulinic acid synthesis rates are increased and correlate with an increased content of glutamyl-transfer RNA reductase. We suggest that LCAA encodes an additional subunit of the Mg protoporphyrin monomethylester cyclase, is required for the stability of CHL27, and contributes to feedback-control of 5-aminolevulinic acid biosynthesis, the rate-limiting step of chlorophyll biosynthesis.
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Affiliation(s)
| | - Annabel Salinas
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany (C.A.A., S.K., W.T., W.L., R.B., M.A.S.); and Plant Physiology Group, Institute of Biology, Humboldt University Berlin, D–10115 Berlin, Germany (A.S., O.C., M.R., B.G.)
| | - Olaf Czarnecki
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany (C.A.A., S.K., W.T., W.L., R.B., M.A.S.); and Plant Physiology Group, Institute of Biology, Humboldt University Berlin, D–10115 Berlin, Germany (A.S., O.C., M.R., B.G.)
| | - Sabine Kahlau
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany (C.A.A., S.K., W.T., W.L., R.B., M.A.S.); and Plant Physiology Group, Institute of Biology, Humboldt University Berlin, D–10115 Berlin, Germany (A.S., O.C., M.R., B.G.)
| | - Maxi Rothbart
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany (C.A.A., S.K., W.T., W.L., R.B., M.A.S.); and Plant Physiology Group, Institute of Biology, Humboldt University Berlin, D–10115 Berlin, Germany (A.S., O.C., M.R., B.G.)
| | - Wolfram Thiele
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany (C.A.A., S.K., W.T., W.L., R.B., M.A.S.); and Plant Physiology Group, Institute of Biology, Humboldt University Berlin, D–10115 Berlin, Germany (A.S., O.C., M.R., B.G.)
| | | | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany (C.A.A., S.K., W.T., W.L., R.B., M.A.S.); and Plant Physiology Group, Institute of Biology, Humboldt University Berlin, D–10115 Berlin, Germany (A.S., O.C., M.R., B.G.)
| | - Bernhard Grimm
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany (C.A.A., S.K., W.T., W.L., R.B., M.A.S.); and Plant Physiology Group, Institute of Biology, Humboldt University Berlin, D–10115 Berlin, Germany (A.S., O.C., M.R., B.G.)
| | - Mark Aurel Schöttler
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D–14476 Potsdam-Golm, Germany (C.A.A., S.K., W.T., W.L., R.B., M.A.S.); and Plant Physiology Group, Institute of Biology, Humboldt University Berlin, D–10115 Berlin, Germany (A.S., O.C., M.R., B.G.)
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Celedon JM, Cline K. Intra-plastid protein trafficking: how plant cells adapted prokaryotic mechanisms to the eukaryotic condition. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:341-51. [PMID: 22750312 DOI: 10.1016/j.bbamcr.2012.06.028] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 06/11/2012] [Accepted: 06/20/2012] [Indexed: 12/14/2022]
Abstract
Protein trafficking and localization in plastids involve a complex interplay between ancient (prokaryotic) and novel (eukaryotic) translocases and targeting machineries. During evolution, ancient systems acquired new functions and novel translocation machineries were developed to facilitate the correct localization of nuclear encoded proteins targeted to the chloroplast. Because of its post-translational nature, targeting and integration of membrane proteins posed the biggest challenge to the organelle to avoid aggregation in the aqueous compartments. Soluble proteins faced a different kind of problem since some had to be transported across three membranes to reach their destination. Early studies suggested that chloroplasts addressed these issues by adapting ancient-prokaryotic machineries and integrating them with novel-eukaryotic systems, a process called 'conservative sorting'. In the last decade, detailed biochemical, genetic, and structural studies have unraveled the mechanisms of protein targeting and localization in chloroplasts, suggesting a highly integrated scheme where ancient and novel systems collaborate at different stages of the process. In this review we focus on the differences and similarities between chloroplast ancestral translocases and their prokaryotic relatives to highlight known modifications that adapted them to the eukaryotic situation. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
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Affiliation(s)
- Jose M Celedon
- Horticultural Sciences Department and Plant Molecular and Cellular Biology, University of Florida, Gainesville, FL 32611, USA
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Chromodomains read the arginine code of post-translational targeting. Nat Struct Mol Biol 2012; 19:260-3. [PMID: 22231402 DOI: 10.1038/nsmb.2196] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 11/07/2011] [Indexed: 11/08/2022]
Abstract
Chromodomains typically recruit protein complexes to chromatin and read the epigenetic histone code by recognizing lysine methylation in histone tails. We report the crystal structure of the chloroplast signal recognition particle (cpSRP) core from Arabidopsis thaliana, with the cpSRP54 tail comprising an arginine-rich motif bound to the second chromodomain of cpSRP43. A twinned aromatic cage reads out two neighboring nonmethylated arginines and adapts chromodomains to a non-nuclear function in post-translational targeting.
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Majeran W, Friso G, Asakura Y, Qu X, Huang M, Ponnala L, Watkins KP, Barkan A, van Wijk KJ. Nucleoid-enriched proteomes in developing plastids and chloroplasts from maize leaves: a new conceptual framework for nucleoid functions. PLANT PHYSIOLOGY 2012; 158:156-89. [PMID: 22065420 PMCID: PMC3252073 DOI: 10.1104/pp.111.188474] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 11/06/2011] [Indexed: 05/18/2023]
Abstract
Plastids contain multiple copies of the plastid chromosome, folded together with proteins and RNA into nucleoids. The degree to which components of the plastid gene expression and protein biogenesis machineries are nucleoid associated, and the factors involved in plastid DNA organization, repair, and replication, are poorly understood. To provide a conceptual framework for nucleoid function, we characterized the proteomes of highly enriched nucleoid fractions of proplastids and mature chloroplasts isolated from the maize (Zea mays) leaf base and tip, respectively, using mass spectrometry. Quantitative comparisons with proteomes of unfractionated proplastids and chloroplasts facilitated the determination of nucleoid-enriched proteins. This nucleoid-enriched proteome included proteins involved in DNA replication, organization, and repair as well as transcription, mRNA processing, splicing, and editing. Many proteins of unknown function, including pentatricopeptide repeat (PPR), tetratricopeptide repeat (TPR), DnaJ, and mitochondrial transcription factor (mTERF) domain proteins, were identified. Strikingly, 70S ribosome and ribosome assembly factors were strongly overrepresented in nucleoid fractions, but protein chaperones were not. Our analysis strongly suggests that mRNA processing, splicing, and editing, as well as ribosome assembly, take place in association with the nucleoid, suggesting that these processes occur cotranscriptionally. The plastid developmental state did not dramatically change the nucleoid-enriched proteome but did quantitatively shift the predominating function from RNA metabolism in undeveloped plastids to translation and homeostasis in chloroplasts. This study extends the known maize plastid proteome by hundreds of proteins, including more than 40 PPR and mTERF domain proteins, and provides a resource for targeted studies on plastid gene expression. Details of protein identification and annotation are provided in the Plant Proteome Database.
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35
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Welte T, Kudva R, Kuhn P, Sturm L, Braig D, Müller M, Warscheid B, Drepper F, Koch HG. Promiscuous targeting of polytopic membrane proteins to SecYEG or YidC by the Escherichia coli signal recognition particle. Mol Biol Cell 2011; 23:464-79. [PMID: 22160593 PMCID: PMC3268725 DOI: 10.1091/mbc.e11-07-0590] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The YidC insertase also integrates multispanning membrane proteins that had been considered to be exclusively SecYEG dependent. Only membrane proteins that require SecA can be inserted only via SecYEG. Targeting to YidC is SRP dependent, and the C-terminus of YidC cross-links to SRP, FtsY, and ribosomal subunits. Protein insertion into the bacterial inner membrane is facilitated by SecYEG or YidC. Although SecYEG most likely constitutes the major integration site, small membrane proteins have been shown to integrate via YidC. We show that YidC can also integrate multispanning membrane proteins such as mannitol permease or TatC, which had been considered to be exclusively integrated by SecYEG. Only SecA-dependent multispanning membrane proteins strictly require SecYEG for integration, which suggests that SecA can only interact with the SecYEG translocon, but not with the YidC insertase. Targeting of multispanning membrane proteins to YidC is mediated by signal recognition particle (SRP), and we show by site-directed cross-linking that the C-terminus of YidC is in contact with SRP, the SRP receptor, and ribosomal proteins. These findings indicate that SRP recognizes membrane proteins independent of the downstream integration site and that many membrane proteins can probably use either SecYEG or YidC for integration. Because protein synthesis is much slower than protein transport, the use of YidC as an additional integration site for multispanning membrane proteins may prevent a situation in which the majority of SecYEG complexes are occupied by translating ribosomes during cotranslational insertion, impeding the translocation of secretory proteins.
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Affiliation(s)
- Thomas Welte
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany
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36
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Dünschede B, Bals T, Funke S, Schünemann D. Interaction studies between the chloroplast signal recognition particle subunit cpSRP43 and the full-length translocase Alb3 reveal a membrane-embedded binding region in Alb3 protein. J Biol Chem 2011; 286:35187-95. [PMID: 21832051 DOI: 10.1074/jbc.m111.250746] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Posttranslational targeting of the light-harvesting chlorophyll a,b-binding proteins depends on the function of the chloroplast signal recognition particle, its receptor cpFtsY, and the translocase Alb3. The thylakoid membrane protein Alb3 of Arabidopsis chloroplasts belongs to the evolutionarily conserved YidC/Oxa1/Alb3 protein family; the members of this family facilitate the insertion, folding, and assembly of membrane proteins in bacteria, mitochondria, and chloroplasts. Here, we analyzed the interaction sites of full-length Alb3 with the cpSRP pathway component cpSRP43 by using in vitro and in vivo studies. Bimolecular fluorescence complementation and Alb3 proteoliposome studies showed that the interaction of cpSRP43 is dependent on a binding domain in the C terminus of Alb3 as well as an additional membrane-embedded binding site in the fifth transmembrane domain (TMD5) of Alb3. The C-terminal binding domain was mapped to residues 374-388, and the binding domain within TMD5 was mapped to residues 314-318 located close to the luminal end of TMD5. A direct binding between cpSRP43 and these binding motifs was shown by pepspot analysis. Further studies using blue-native gel electrophoresis revealed that full-length Alb3 is able to form dimers. This finding and the identification of a membrane-embedded cpSRP43 binding site in Alb3 support a model in which cpSRP43 inserts into a dimeric Alb3 translocation pore during cpSRP-dependent delivery of light-harvesting chlorophyll a,b-binding proteins.
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Affiliation(s)
- Beatrix Dünschede
- Molecular Biology of Plant Organelles, Ruhr-University Bochum, 44780 Bochum, Germany
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37
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LTD is a protein required for sorting light-harvesting chlorophyll-binding proteins to the chloroplast SRP pathway. Nat Commun 2011; 2:277. [DOI: 10.1038/ncomms1278] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 03/16/2011] [Indexed: 11/08/2022] Open
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