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Faisal MB, Gechev TS, Mueller-Roeber B, Dijkwel PP. Putative alternative translation start site-encoding nucleotides of CPR5 regulate growth and resistance. BMC PLANT BIOLOGY 2020; 20:295. [PMID: 32600419 PMCID: PMC7322872 DOI: 10.1186/s12870-020-02485-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The Arabidopsis CONSTITUTIVE EXPRESSER of PATHOGENESIS-RELATED GENES 5 (CPR5) has recently been shown to play a role in gating as part of the nuclear pore complex (NPC). Mutations in CPR5 cause multiple defects, including aberrant trichomes, reduced ploidy levels, reduced growth and enhanced resistance to bacterial and fungal pathogens. The pleiotropic nature of cpr5 mutations implicates that the CPR5 protein affects multiple pathways. However, little is known about the structural features that allow CPR5 to affect the different pathways. RESULTS Our in silico studies suggest that in addition to three clusters of putative nuclear localization signals and four or five transmembrane domains, CPR5 contains two putative alternative translation start sites. To test the role of the methionine-encoding nucleotides implicated in those sites, metCPR5 cDNAs, in which the relevant nucleotides were changed to encode glutamine, were fused to the CPR5 native promoter and the constructs transformed to cpr5-2 plants to complement cpr5-compromised phenotypes. The control and metCPR5 constructs were able to complement all cpr5 phenotypes, although the extent of complementation depended on the specific complementing plant lines. Remarkably, plants transformed with metCPR5 constructs showed larger leaves and displayed reduced resistance when challenged to Pseudomonas syringae pv Pst DC3000, as compared to control plants. Thus, the methionine-encoding nucleotides regulate growth and resistance. We propose that structural features of the CPR5 N-terminus are implicated in selective gating of proteins involved in regulating the balance between growth and resistance. CONCLUSION Plants need to carefully balance the amount of resources used for growth and resistance. The Arabidopsis CPR5 protein regulates plant growth and immunity. Here we show that N-terminal features of CPR5 are involved in the regulation of the balance between growth and resistance. These findings may benefit efforts to improve plant yield, while maintaining optimal levels of disease resistance.
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Affiliation(s)
- Muhammad B Faisal
- School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Tsanko S Gechev
- Center of Plant Systems Biology and Biotechnology, 4000, Plovdiv, Bulgaria
| | - Bernd Mueller-Roeber
- Center of Plant Systems Biology and Biotechnology, 4000, Plovdiv, Bulgaria
- Department of Molecular Biology, Institute of Biochemistry and Biology, University of Potsdam, 14476, Potsdam, Germany
| | - Paul P Dijkwel
- School of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
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2
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Cabout S, Leask MP, Varghese S, Yi J, Peters B, Conze LL, Köhler C, Brownfield L. The meiotic regulator JASON utilizes alternative translation initiation sites to produce differentially localized forms. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:4205-4217. [PMID: 28922756 PMCID: PMC5853252 DOI: 10.1093/jxb/erx222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 06/06/2017] [Indexed: 06/07/2023]
Abstract
The JASON (JAS) protein plays an important role in maintaining an organelle band across the equator of male meiotic cells during the second division, with its loss leading to unreduced pollen in Arabidopsis. In roots cells, JAS localizes to the Golgi, tonoplast and plasma membrane. Here we explore the mechanism underlying the localization of JAS. Overall, our data show that leaky ribosom scanning and alternative translation initiation sites (TISs) likely leads to the formation of two forms of JAS: a long version with an N-terminal Golgi localization signal and a short version with a different N-terminal signal targeting the protein to the plasma membrane. The ratio of the long and short forms of JAS is developmentally regulated, with both being produced in roots but the short form being predominant and functional during meiosis. This regulation of TISs in meiocytes ensures that the short version of JAS is formed during meiosis to ensure separation of chromosome groups and the production of reduced pollen. We hypothesize that increased occurrence of unreduced pollen under stress conditions may be a consequence of altered usage of JAS TISs during stress.
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Affiliation(s)
- Simon Cabout
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Megan P Leask
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Shiny Varghese
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Jun Yi
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Benjamin Peters
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Lei Liu Conze
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Claudia Köhler
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
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3
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Gualberto JM, Newton KJ. Plant Mitochondrial Genomes: Dynamics and Mechanisms of Mutation. ANNUAL REVIEW OF PLANT BIOLOGY 2017; 68:225-252. [PMID: 28226235 DOI: 10.1146/annurev-arplant-043015-112232] [Citation(s) in RCA: 231] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The large mitochondrial genomes of angiosperms are unusually dynamic because of recombination activities involving repeated sequences. These activities generate subgenomic forms and extensive genomic variation even within the same species. Such changes in genome structure are responsible for the rapid evolution of plant mitochondrial DNA and for the variants associated with cytoplasmic male sterility and abnormal growth phenotypes. Nuclear genes modulate these processes, and over the past decade, several of these genes have been identified. They are involved mainly in pathways of DNA repair by homologous recombination and mismatch repair, which appear to be essential for the faithful replication of the mitogenome. Mutations leading to the loss of any of these activities release error-prone repair pathways, resulting in increased ectopic recombination, genome instability, and heteroplasmy. We review the present state of knowledge of the genes and pathways underlying mitochondrial genome stability.
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Affiliation(s)
- José M Gualberto
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, 67084 Strasbourg, France;
| | - Kathleen J Newton
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211;
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Kim HJ, Kim HJ, Jeong JE, Baek JY, Jeong J, Kim S, Kim YM, Kim Y, Nam JH, Huh SH, Seo J, Jin BK, Lee KJ. N-terminal truncated UCH-L1 prevents Parkinson's disease associated damage. PLoS One 2014; 9:e99654. [PMID: 24959670 PMCID: PMC4069018 DOI: 10.1371/journal.pone.0099654] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 05/16/2014] [Indexed: 11/20/2022] Open
Abstract
Ubiquitin C-terminal hydrolase-L1 (UCH-L1) has been proposed as one of the Parkinson's disease (PD) related genes, but the possible molecular connection between UCH-L1 and PD is not well understood. In this study, we discovered an N-terminal 11 amino acid truncated variant UCH-L1 that we called NT-UCH-L1, in mouse brain tissue as well as in NCI-H157 lung cancer and SH-SY5Y neuroblastoma cell lines. In vivo experiments and hydrogen-deuterium exchange (HDX) with tandem mass spectrometry (MS) studies showed that NT-UCH-L1 is readily aggregated and degraded, and has more flexible structure than UCH-L1. Post-translational modifications including monoubiquitination and disulfide crosslinking regulate the stability and cellular localization of NT-UCH-L1, as confirmed by mutational and proteomic studies. Stable expression of NT-UCH-L1 decreases cellular ROS levels and protects cells from H2O2, rotenone and CCCP-induced cell death. NT-UCH-L1-expressing transgenic mice are less susceptible to degeneration of nigrostriatal dopaminergic neurons seen in the MPTP mouse model of PD, in comparison to control animals. These results suggest that NT-UCH-L1 may have the potential to prevent neural damage in diseases like PD.
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Affiliation(s)
- Hee-Jung Kim
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
| | - Hyun Jung Kim
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
| | - Jae-Eun Jeong
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
| | - Jeong Yeob Baek
- Department of Biochemistry and Molecular Biology, Neurodegeneration Control Research Center, School of Medicine, Kyung Hee University, Seoul, Korea
| | - Jaeho Jeong
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
| | - Sun Kim
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
| | - Young-Mee Kim
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
| | - Youhwa Kim
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
| | - Jin Han Nam
- Department of Biochemistry and Molecular Biology, Neurodegeneration Control Research Center, School of Medicine, Kyung Hee University, Seoul, Korea
| | - Sue Hee Huh
- Department of Biochemistry and Molecular Biology, Neurodegeneration Control Research Center, School of Medicine, Kyung Hee University, Seoul, Korea
| | - Jawon Seo
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
| | - Byung Kwan Jin
- Department of Biochemistry and Molecular Biology, Neurodegeneration Control Research Center, School of Medicine, Kyung Hee University, Seoul, Korea
- * E-mail: (KJL); (BKJ)
| | - Kong-Joo Lee
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, Korea
- * E-mail: (KJL); (BKJ)
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Moriyama T, Sato N. Enzymes involved in organellar DNA replication in photosynthetic eukaryotes. FRONTIERS IN PLANT SCIENCE 2014; 5:480. [PMID: 25278952 PMCID: PMC4166229 DOI: 10.3389/fpls.2014.00480] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 08/30/2014] [Indexed: 05/18/2023]
Abstract
Plastids and mitochondria possess their own genomes. Although the replication mechanisms of these organellar genomes remain unclear in photosynthetic eukaryotes, several organelle-localized enzymes related to genome replication, including DNA polymerase, DNA primase, DNA helicase, DNA topoisomerase, single-stranded DNA maintenance protein, DNA ligase, primer removal enzyme, and several DNA recombination-related enzymes, have been identified. In the reference Eudicot plant Arabidopsis thaliana, the replication-related enzymes of plastids and mitochondria are similar because many of them are dual targeted to both organelles, whereas in the red alga Cyanidioschyzon merolae, plastids and mitochondria contain different replication machinery components. The enzymes involved in organellar genome replication in green plants and red algae were derived from different origins, including proteobacterial, cyanobacterial, and eukaryotic lineages. In the present review, we summarize the available data for enzymes related to organellar genome replication in green plants and red algae. In addition, based on the type and distribution of replication enzymes in photosynthetic eukaryotes, we discuss the transitional history of replication enzymes in the organelles of plants.
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Affiliation(s)
- Takashi Moriyama
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of TokyoTokyo, Japan
- Japan Science and Technology Agency – Core Research for Evolutional Science and TechnologyTokyo, Japan
| | - Naoki Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of TokyoTokyo, Japan
- Japan Science and Technology Agency – Core Research for Evolutional Science and TechnologyTokyo, Japan
- *Correspondence: Naoki Sato, Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan e-mail:
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Kang M, Abdelmageed H, Lee S, Reichert A, Mysore KS, Allen RD. AtMBP-1, an alternative translation product of LOS2, affects abscisic acid responses and is modulated by the E3 ubiquitin ligase AtSAP5. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 76:481-93. [PMID: 23952686 DOI: 10.1111/tpj.12312] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 08/06/2013] [Accepted: 08/09/2013] [Indexed: 05/19/2023]
Abstract
The LOS2 gene in Arabidopsis encodes an enolase with 72% amino acid sequence identity with human ENO1. In mammalian cells, the α-enolase (ENO1) gene encodes both a 48 kDa glycolytic enzyme and a 37 kDa transcriptional suppressor protein that are targeted to different cellular compartments. The tumor suppressor c-myc binding protein (MBP-1), which is alternatively translated from the second start codon of ENO1 transcripts, is preferentially localized in nuclei while α-enolase is found in the cytoplasm. We report here that an Arabidopsis MBP-1-like protein (AtMBP-1) is alternatively translated from full-length LOS2 transcripts using a second start codon. Like mammalian MBP-1, this truncated form of LOS2 has little, if any, enolase activity, indicating that an intact N-terminal region of LOS2 is critical for catalysis. AtMBP-1 has a short half-life in vivo and is stabilized by the proteasome inhibitor MG132, indicating that it is degraded via the ubiquitin-dependent proteasome pathway. Arabidopsis plants that over-express AtMBP-1 are hypersensitive to abscisic acid (ABA) during seed germination and show defects in vegetative growth and lateral stem development. AtMBP-1 interacts directly with the E3 ubiquitin ligase AtSAP5 and co-expression of these proteins resulted in destabilization of AtMBP-1 in vivo and abolished the developmental defects associated with AtMBP-1 over-expression. Thus, AtMBP-1 is as a bona fide alternative translation product of LOS2. Accumulation of this factor is limited by ubiquitin-dependent destabilization, apparently mediated by AtSAP5.
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Affiliation(s)
- Miyoung Kang
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, 74078, USA; Institute for Agricultural Bioscience, Oklahoma State University, Ardmore, OK, 79413, USA
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7
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New universal rules of eukaryotic translation initiation fidelity. PLoS Comput Biol 2013; 9:e1003136. [PMID: 23874179 PMCID: PMC3708879 DOI: 10.1371/journal.pcbi.1003136] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/28/2013] [Indexed: 11/26/2022] Open
Abstract
The accepted model of eukaryotic translation initiation begins with the scanning of the transcript by the pre-initiation complex from the 5′end until an ATG codon with a specific nucleotide (nt) context surrounding it is recognized (Kozak rule). According to this model, ATG codons upstream to the beginning of the ORF should affect translation. We perform for the first time, a genome-wide statistical analysis, uncovering a new, more comprehensive and quantitative, set of initiation rules for improving the cost of translation and its efficiency. Analyzing dozens of eukaryotic genomes, we find that in all frames there is a universal trend of selection for low numbers of ATG codons; specifically, 16–27 codons upstream, but also 5–11 codons downstream of the START ATG, include less ATG codons than expected. We further suggest that there is selection for anti optimal ATG contexts in the vicinity of the START ATG. Thus, the efficiency and fidelity of translation initiation is encoded in the 5′UTR as required by the scanning model, but also at the beginning of the ORF. The observed nt patterns suggest that in all the analyzed organisms the pre-initiation complex often misses the START ATG of the ORF, and may start translation from an alternative initiation start-site. Thus, to prevent the translation of undesired proteins, there is selection for nucleotide sequences with low affinity to the pre-initiation complex near the beginning of the ORF. With the new suggested rules we were able to obtain a twice higher correlation with ribosomal density and protein levels in comparison to the Kozak rule alone (e.g. for protein levels r = 0.7 vs. r = 0.31; p<10−12). Gene translation is an important step of the intra-cellular protein synthesis, which is a central process in all living organisms. Thus, understanding how translation efficiency is encoded in transcripts has ramifications to every biomedical discipline. The aim of the current study is to decipher the way translation initiation fidelity is encoded in eukaryotic transcripts, and how evolution shapes the beginning of transcripts. Based on the genomes of dozens of organisms we were able to derive a new, more precise, set of rules related to this process, facilitating a high resolution view of the mechanisms aiding translation initiation fidelity. Among others, we show that there is a universal trend of selection for low numbers of ATG codons upstream, but also in the 5–11 codons downstream of the START ATG, presumably to prevent translation of alternative ORFs over the main one. With the new suggested rules we were able to obtain a twice higher correlation with ribosomal density and protein levels in comparison to the previous translation initiation efficiency rule.
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8
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Abstract
Cotranslational protein N-terminal modifications, including proteolytic maturation such as initiator methionine excision by methionine aminopeptidases and N-terminal blocking, occur universally. Protein alpha-N-acetylation, or the transfer of the acetyl moiety of acetyl-coenzyme A to nascent protein N-termini, catalysed by multisubunit N-terminal acetyltransferase complexes, generally takes place during protein translation. Nearly all protein modifications are known to influence different protein aspects such as folding, stability, activity and localization, and several studies have indicated similar functions for protein alpha-N-acetylation. However, until recently, protein alpha-N-acetylation remained poorly explored, mainly due to the absence of targeted proteomics technologies. The recent emergence of N-terminomics technologies that allow isolation of protein N-terminal peptides, together with proteogenomics efforts combining experimental and informational content have greatly boosted the field of alpha-N-acetylation. In this review, we report on such emerging technologies as well as on breakthroughs in our understanding of protein N-terminal biology.
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Affiliation(s)
- Petra Van Damme
- Department of Medical Protein Research, VIB, Ghent, Belgium.
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9
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Bazykin GA, Kochetov AV. Alternative translation start sites are conserved in eukaryotic genomes. Nucleic Acids Res 2010; 39:567-77. [PMID: 20864444 PMCID: PMC3025576 DOI: 10.1093/nar/gkq806] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Alternative start AUG codons within a single transcript can contribute to diversity of the proteome; however, their functional significance remains controversial. Here, we provide comparative genomics evidence that alternative start codons are under negative selection in vertebrates, insects and yeast. In genes where the annotated start codon (sAUG) resides within the suboptimal nucleotide context, the downstream in-frame AUG codons (dAUG) among the first ∼30 codon sites are significantly more conserved between species than in genes where the sAUG resides within the optimal context. Proteomics data show that this difference is not an annotation artifact and that dAUGs are in fact under selection as alternative start sites. The key optimal, and sometimes suboptimal, context-determining nucleotides of both the sAUG and dAUGs are conserved. Selection for secondary start sites is stronger in genes with the weak primary start site. Genes with multiple conserved start sites are enriched for transcription factors, and tend to have longer 5'UTRs and higher degree of alternative splicing. Together, these results imply that the use of alternative start sites by means of leaky mRNA scanning is a functional mechanism under selection for increased efficiency of translation and/or for translation of different N-terminal protein variants.
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Affiliation(s)
- Georgii A Bazykin
- Institute for Information Transmission Problems of the Russian Academy of Sciences (Kharkevich Institute), Moscow, Russia.
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10
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Kochetov AV. Alternative translation start sites and hidden coding potential of eukaryotic mRNAs. Bioessays 2008; 30:683-91. [PMID: 18536038 DOI: 10.1002/bies.20771] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It is widely suggested that a eukaryotic mRNA typically contains one translation start site and encodes a single functional protein product. However, according to current points of view on translation initiation mechanisms, eukaryotic ribosomes can recognize several alternative translation start sites and the number of experimentally verified examples of alternative translation is growing rapidly. Also, the frequent occurrence of alternative translation events and their functional significance are supported by the results of computational evaluations. The functional role of alternative translation and its contribution to eukaryotic proteome complexity are discussed.
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11
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Millar AH, Small ID, Day DA, Whelan J. Mitochondrial biogenesis and function in Arabidopsis. THE ARABIDOPSIS BOOK 2008; 6:e0111. [PMID: 22303236 PMCID: PMC3243404 DOI: 10.1199/tab.0111] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Mitochondria represent the powerhouse of cells through their synthesis of ATP. However, understanding the role of mitochondria in the growth and development of plants will rely on a much deeper appreciation of the complexity of this organelle. Arabidopsis research has provided clear identification of mitochondrial components, allowed wide-scale analysis of gene expression, and has aided reverse genetic manipulation to test the impact of mitochondrial component loss on plant function. Forward genetics in Arabidopsis has identified mitochondrial involvement in mutations with notable impacts on plant metabolism, growth and development. Here we consider the evidence for components involved in mitochondria biogenesis, metabolism and signalling to the nucleus.
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Affiliation(s)
- A. Harvey Millar
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009
| | - Ian D. Small
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009
| | - David A. Day
- School of Biological Sciences, The University of Sydney 2006, NSW, Australia
| | - James Whelan
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009
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Habala L, Dworak C, Nazarov AA, Hartinger CG, Abramkin SA, Arion VB, Lindner W, Galanski M, Keppler BK. Methyl-substituted trans-1,2-cyclohexanediamines as new ligands for oxaliplatin-type complexes. Tetrahedron 2008. [DOI: 10.1016/j.tet.2007.10.069] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Shultz RW, Tatineni VM, Hanley-Bowdoin L, Thompson WF. Genome-wide analysis of the core DNA replication machinery in the higher plants Arabidopsis and rice. PLANT PHYSIOLOGY 2007; 144:1697-714. [PMID: 17556508 PMCID: PMC1949880 DOI: 10.1104/pp.107.101105] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 05/29/2007] [Indexed: 05/15/2023]
Abstract
Core DNA replication proteins mediate the initiation, elongation, and Okazaki fragment maturation functions of DNA replication. Although this process is generally conserved in eukaryotes, important differences in the molecular architecture of the DNA replication machine and the function of individual subunits have been reported in various model systems. We have combined genome-wide bioinformatic analyses of Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) with published experimental data to provide a comprehensive view of the core DNA replication machinery in plants. Many components identified in this analysis have not been studied previously in plant systems, including the GINS (go ichi ni san) complex (PSF1, PSF2, PSF3, and SLD5), MCM8, MCM9, MCM10, NOC3, POLA2, POLA3, POLA4, POLD3, POLD4, and RNASEH2. Our results indicate that the core DNA replication machinery from plants is more similar to vertebrates than single-celled yeasts (Saccharomyces cerevisiae), suggesting that animal models may be more relevant to plant systems. However, we also uncovered some important differences between plants and vertebrate machinery. For example, we did not identify geminin or RNASEH1 genes in plants. Our analyses also indicate that plants may be unique among eukaryotes in that they have multiple copies of numerous core DNA replication genes. This finding raises the question of whether specialized functions have evolved in some cases. This analysis establishes that the core DNA replication machinery is highly conserved across plant species and displays many features in common with other eukaryotes and some characteristics that are unique to plants.
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Affiliation(s)
- Randall W Shultz
- Department of Plant Biology , North Carolina State University, Raleigh, North Carolina 27695, USA
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Schwacke R, Fischer K, Ketelsen B, Krupinska K, Krause K. Comparative survey of plastid and mitochondrial targeting properties of transcription factors in Arabidopsis and rice. Mol Genet Genomics 2007; 277:631-46. [PMID: 17295027 DOI: 10.1007/s00438-007-0214-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 01/14/2007] [Indexed: 12/24/2022]
Abstract
A group of nuclear transcription factors, the Whirly proteins, were recently shown to be targeted also to chloroplasts and mitochondria. In order to find out whether other proteins might share this feature, an in silico-based screening of transcription factors from Arabidopsis and rice was carried out with the aim of identifying putative N-terminal chloroplast and mitochondrial targeting sequences. For this, the individual predictions of several independent programs were combined to a consensus prediction using a naïve Bayes method. This consensus prediction shows a higher specificity at a given sensitivity value than each of the single programs. In both species, transcription factors from a variety of protein families that possess putative N-terminal plastid or mitochondrial target peptides as well as nuclear localization sequences, were found. A search for homologues within members of the AP2/EREBP protein family revealed that target peptide-containing proteins are conserved among monocotyledonous and dicotyledonous species. Fusion of one of these proteins to GFP revealed, indeed, a dual targeting activity of this protein. We propose that dually targeted transcription factors might be involved in the communication between the nucleus and the organelles in plant cells. We further discuss how recent results on the physical interaction between the organelles and the nucleus could have significance for the regulation of the localization of these proteins.
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Affiliation(s)
- Rainer Schwacke
- Institute of Botany, University of Cologne, Gyrhofstr. 15, 50931 Cologne, Germany
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15
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Kochetov AV. Alternative translation start sites and their significance for eukaryotic proteomes. Mol Biol 2006. [DOI: 10.1134/s0026893306050049] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Sunderland PA, West CE, Waterworth WM, Bray CM. An evolutionarily conserved translation initiation mechanism regulates nuclear or mitochondrial targeting of DNA ligase 1 in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 47:356-67. [PMID: 16790030 DOI: 10.1111/j.1365-313x.2006.02791.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The Arabidopsis DNA ligase 1 gene (AtLIG1) is indispensable for cell viability. AtLIG1 expresses one major and two minor mRNA transcripts differing only in the length of the 5' untranslated leader sequences preceding a common ORF. Control of AtLIG1 isoform production and intracellular targeting depends upon mechanisms controlling the choice of translation initiation site within the AtLIG1 ORF. Confocal laser scanning microscopy of green fluorescent protein-tagged AtLIG1 isoforms expressed in Arabidopsis revealed that translation of AtLIG1 mRNA transcripts from the first in-frame start codon produces an AtLIG1 isoform that is targeted exclusively to the mitochondria. Translation initiation from the second in-frame start codon produces an AtLIG1 isoform targeted only to the nucleus. There is no evidence for AtLIG1-GFP being targeted to chloroplasts. The mitochondrial AtLIG1 isoform possesses both an N-terminal mitochondrial-targeting signal and an internal bipartite nuclear localization signal (NLS) yet is targeted only to mitochondria, demonstrating a hierarchical dominance of the mitochondrial presequence over the NLS. The length of the 5'-UTR and more significantly the nucleotide context around alternative start codons in the AtLIG1 transcripts affect translation initiation to ensure a balanced synthesis of both nuclear and mitochondrial AtLIG1 isoforms, probably via a context-dependent leaky ribosome scanning mechanism.
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Affiliation(s)
- Paul A Sunderland
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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