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Coe K, Bostan H, Rolling W, Turner-Hissong S, Macko-Podgórni A, Senalik D, Liu S, Seth R, Curaba J, Mengist MF, Grzebelus D, Van Deynze A, Dawson J, Ellison S, Simon P, Iorizzo M. Population genomics identifies genetic signatures of carrot domestication and improvement and uncovers the origin of high-carotenoid orange carrots. NATURE PLANTS 2023; 9:1643-1658. [PMID: 37770615 PMCID: PMC10581907 DOI: 10.1038/s41477-023-01526-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 08/28/2023] [Indexed: 09/30/2023]
Abstract
Here an improved carrot reference genome and resequencing of 630 carrot accessions were used to investigate carrot domestication and improvement. The study demonstrated that carrot was domesticated during the Early Middle Ages in the region spanning western Asia to central Asia, and orange carrot was selected during the Renaissance period, probably in western Europe. A progressive reduction of genetic diversity accompanied this process. Genes controlling circadian clock/flowering and carotenoid accumulation were under selection during domestication and improvement. Three recessive genes, at the REC, Or and Y2 quantitative trait loci, were essential to select for the high α- and β-carotene orange phenotype. All three genes control high α- and β-carotene accumulation through molecular mechanisms that regulate the interactions between the carotenoid biosynthetic pathway, the photosynthetic system and chloroplast biogenesis. Overall, this study elucidated carrot domestication and breeding history and carotenoid genetics at a molecular level.
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Affiliation(s)
- Kevin Coe
- Plants for Human Health Institute, North Carolina State University, Kannapolis, NC, USA
- Department of Plant and Agroecosystem Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Hamed Bostan
- Plants for Human Health Institute, North Carolina State University, Kannapolis, NC, USA
| | - William Rolling
- Department of Plant and Agroecosystem Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Agricultural Research Service, Vegetable Crops Research Unit, US Department of Agriculture, Madison, WI, USA
| | | | - Alicja Macko-Podgórni
- Department of Plant Biology and Biotechnology, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, Krakow, Poland
| | - Douglas Senalik
- Department of Plant and Agroecosystem Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Agricultural Research Service, Vegetable Crops Research Unit, US Department of Agriculture, Madison, WI, USA
| | - Su Liu
- Plants for Human Health Institute, North Carolina State University, Kannapolis, NC, USA
| | - Romit Seth
- Plants for Human Health Institute, North Carolina State University, Kannapolis, NC, USA
| | - Julien Curaba
- Plants for Human Health Institute, North Carolina State University, Kannapolis, NC, USA
| | - Molla Fentie Mengist
- Plants for Human Health Institute, North Carolina State University, Kannapolis, NC, USA
| | - Dariusz Grzebelus
- Department of Plant Biology and Biotechnology, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, Krakow, Poland
| | - Allen Van Deynze
- Seed Biotechnology Center, University of California, Davis, CA, USA
| | - Julie Dawson
- Department of Plant and Agroecosystem Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Shelby Ellison
- Department of Plant and Agroecosystem Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Philipp Simon
- Department of Plant and Agroecosystem Sciences, University of Wisconsin-Madison, Madison, WI, USA.
- Agricultural Research Service, Vegetable Crops Research Unit, US Department of Agriculture, Madison, WI, USA.
| | - Massimo Iorizzo
- Plants for Human Health Institute, North Carolina State University, Kannapolis, NC, USA.
- Department of Horticultural Science, North Carolina State University, Raleigh, NC, USA.
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2
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Zhao X, Zhao Y, Gou M, Liu CJ. Tissue-preferential recruitment of electron transfer chains for cytochrome P450-catalyzed phenolic biosynthesis. SCIENCE ADVANCES 2023; 9:eade4389. [PMID: 36630494 PMCID: PMC9833660 DOI: 10.1126/sciadv.ade4389] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Cytochrome P450 system consists of P450 monooxygenase and redox pattern(s). While the importance of monooxygenases in plant metabolism is well documented, the metabolic roles of the related redox components have been largely overlooked. Here, we show that distinct electron transfer chains are recruited in phenylpropanoid-monolignol P450 systems to support the synthesis and distribution of different classes of phenolics in different plant tissues. While Arabidopsis cinnamate 4-hydroxylase adopts conventional NADPH-cytochrome P450 oxidoreductase (CPR) electron transfer chain for its para-hydroxylation reaction, ferulate 5-hydroxylase uses both NADPH-CPR-cytochrome b5 (CB5) and NADH-cytochrome b5 reductase-CB5 chains to support benzene ring 5-hydroxylation, in which the former route is primarily recruited in the stem for syringyl lignin synthesis, while the latter dominates in the syntheses of 5-hydroxylated phenolics in seeds and seed coat suberin. Our study unveils an additional layer of complexity and versatility of P450 system that the plants evolved for diversifying phenolic repertoires.
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3
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Liu CJ. Cytochrome b 5: A versatile electron carrier and regulator for plant metabolism. FRONTIERS IN PLANT SCIENCE 2022; 13:984174. [PMID: 36212330 PMCID: PMC9539407 DOI: 10.3389/fpls.2022.984174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/19/2022] [Indexed: 06/16/2023]
Abstract
Cytochrome b 5 (CB5) is a small heme-binding protein, known as an electron donor delivering reducing power to the terminal enzymes involved in oxidative reactions. In plants, the CB5 protein family is substantially expanded both in its isoform numbers and cellular functions, compared to its yeast and mammalian counterparts. As an electron carrier, plant CB5 proteins function not only in fatty acid desaturation, hydroxylation and elongation, but also in the formation of specialized metabolites such as flavonoids, phenolic esters, and heteropolymer lignin. Furthermore, plant CB5s are found to interact with different non-catalytic proteins such as ethylene signaling regulator, cell death inhibitor, and sugar transporters, implicating their versatile regulatory roles in coordinating different metabolic and cellular processes, presumably in respect to the cellular redox status and/or carbon availability. Compared to the plentiful studies on biochemistry and cellular functions of mammalian CB5 proteins, the cellular and metabolic roles of plant CB5 proteins have received far less attention. This article summarizes the fragmentary information pertaining to the discovery of plant CB5 proteins, and discusses the conventional and peculiar functions that plant CB5s might play in different metabolic and cellular processes. Gaining comprehensive insight into the biological functions of CB5 proteins could offer effective biotechnological solutions to tailor plant chemodiversity and cellular responses to environment stimuli.
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Iqbal T, Das D. Biochemical Investigation of Membrane-Bound Cytochrome b5 and the Catalytic Domain of Cytochrome b5 Reductase from Arabidopsis thaliana. Biochemistry 2022; 61:909-921. [PMID: 35475372 DOI: 10.1021/acs.biochem.2c00002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The endoplasmic reticulum (ER) membrane of plant cells contains several enzymes responsible for the biosynthesis of a diverse range of molecules essential for plant growth and holds potential for industrial applications. Many of these enzymes are dependent on electron transfer proteins to sustain their catalytic cycles. In plants, two crucial ER-bound electron transfer proteins are cytochrome b5 and cytochrome b5 reductase, which catalyze the stepwise transfer of electrons from NADH to redox enzymes such as fatty acid desaturases, cytochrome P450s, and plant aldehyde decarbonylase. Despite the high significance of plant cytochrome b5 and cytochrome b5 reductase, they have eluded detailed characterization to date. Here, we overexpressed the full-length membrane-bound cytochrome b5 isoform B from the model plant Arabidopsis thaliana in Escherichia coli, purified the protein employing detergents as well as styrene-maleic acid (SMA) copolymers, and biochemically characterized the protein. The SMA-encapsulated cytochrome b5 exhibits a discoidal shape and the characteristic features of the active heme-bound state. We also overexpressed and purified the soluble domain of cytochrome b5 reductase from A. thaliana, establishing its activity, stability, and kinetic parameters. Further, we demonstrated that the plant cytochrome b5, purified in detergents and styrene maleic acid lipid particles (SMALPs), readily accepts electrons from the cognate plant cytochrome b5 reductase and distant electron mediators such as plant NADPH-cytochrome P450 oxidoreductase and cyanobacterial NADPH-ferredoxin reductase. We also measured the kinetic parameters of cytochrome b5 reductase for cytochrome b5. Our studies are the first to report the purification and detailed biochemical characterization of the plant cytochrome b5 and cytochrome b5 reductase from the bacterial overexpression system.
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Affiliation(s)
- Tabish Iqbal
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Debasis Das
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, Karnataka 560012, India
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5
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Zhao X, Liu CJ. Biocatalytic system for comparatively assessing the functional association of monolignol cytochrome P450 monooxygenases with their redox partners. Methods Enzymol 2022; 676:133-158. [DOI: 10.1016/bs.mie.2022.07.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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6
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An endoplasmic reticulum-localized cytochrome b 5 regulates high-affinity K + transport in response to salt stress in rice. Proc Natl Acad Sci U S A 2021; 118:2114347118. [PMID: 34876526 PMCID: PMC8685926 DOI: 10.1073/pnas.2114347118] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2021] [Indexed: 11/18/2022] Open
Abstract
High-affinity K+ (HAK) transporter-mediated K+ uptake has an important role when plants are subjected to stresses. This work identifies a mechanism of HAK regulation. The affinity of HAK at the plasma membrane for K+ depends on the binding of a cytochrome (CYB5) protein at the endoplasmic reticulum. This improves K+ uptake and the ability of plants to survive under saline conditions. The HAK–CYB5 interaction not only constitutes a mechanism of HAK regulation but also reflects interorganelle communication mediated by functional protein interactions under conditions of stress. Potassium (K+) is an essential element for growth and development in both animals and plants, while high levels of environmental sodium (Na+) represent a threat to most plants. The uptake of K+ from high-saline environments is an essential mechanism to maintain intracellular K+/Na+ homeostasis, which can help reduce toxicity caused by Na+ accumulation, thereby improving the salt tolerance of plants. However, the mechanisms and regulation of K+-uptake during salt stress remain poorly understood. In this study, we identified an endoplasmic reticulum–localized cytochrome b5 (OsCYB5-2) that interacted with a high-affinity K+ transporter (OsHAK21) at the plasma membrane. The association of OsCYB5-2 with the OsHAK21 transporter caused an increase in transporter activity by enhancing the apparent affinity for K+-binding but not Na+-binding. Heme binding to OsCYB5-2 was essential for the regulation of OsHAK21. High salinity directly triggered the OsHAK21–OsCYB5-2 interaction, promoting OsHAK21-mediated K+-uptake and restricting Na+ entry into cells; this maintained intracellular K+/Na+ homeostasis in rice cells. Finally, overexpression of OsCYB5-2 increased OsHAK21-mediated K+ transport and improved salt tolerance in rice seedlings. This study revealed a posttranslational regulatory mechanism for HAK transporter activity mediated by a cytochrome b5 and highlighted the coordinated action of two proteins to perceive Na+ in response to salt stress.
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7
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Mehlhorn DG, Asseck LY, Grefen C. Looking for a safe haven: tail-anchored proteins and their membrane insertion pathways. PLANT PHYSIOLOGY 2021; 187:1916-1928. [PMID: 35235667 PMCID: PMC8644595 DOI: 10.1093/plphys/kiab298] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/05/2021] [Indexed: 06/14/2023]
Abstract
Insertion of membrane proteins into the lipid bilayer is a crucial step during their biosynthesis. Eukaryotic cells face many challenges in directing these proteins to their predestined target membrane. The hydrophobic signal peptide or transmembrane domain (TMD) of the nascent protein must be shielded from the aqueous cytosol and its target membrane identified followed by transport and insertion. Components that evolved to deal with each of these challenging steps range from chaperones to receptors, insertases, and sophisticated translocation complexes. One prominent translocation pathway for most proteins is the signal recognition particle (SRP)-dependent pathway which mediates co-translational translocation of proteins across or into the endoplasmic reticulum (ER) membrane. This textbook example of protein insertion is stretched to its limits when faced with secretory or membrane proteins that lack an amino-terminal signal sequence or TMD. Particularly, a large group of so-called tail-anchored (TA) proteins that harbor a single carboxy-terminal TMD require an alternative, post-translational insertion route into the ER membrane. In this review, we summarize the current research in TA protein insertion with a special focus on plants, address challenges, and highlight future research avenues.
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Affiliation(s)
- Dietmar G Mehlhorn
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Lisa Y Asseck
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Christopher Grefen
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
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8
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Wojcik S, Kriechbaumer V. Go your own way: membrane-targeting sequences. PLANT PHYSIOLOGY 2021; 185:608-618. [PMID: 33822216 PMCID: PMC8133554 DOI: 10.1093/plphys/kiaa058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/19/2020] [Indexed: 05/05/2023]
Abstract
Membrane-targeting sequences, connected targeting mechanisms, and co-factors orchestrate primary targeting of proteins to membranes.
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Affiliation(s)
- Stefan Wojcik
- Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Verena Kriechbaumer
- Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
- Author for communication: (V.K.)
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9
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Sandor A, Fricker MD, Kriechbaumer V, Sweetlove LJ. IntEResting structures: formation and applications of organized smooth endoplasmic reticulum in plant cells. PLANT PHYSIOLOGY 2021; 185:550-561. [PMID: 33822222 PMCID: PMC8892044 DOI: 10.1104/pp.20.00719] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 07/21/2020] [Indexed: 06/12/2023]
Abstract
The endoplasmic reticulum (ER) is an organelle with remarkable plasticity, capable of rapidly changing its structure to accommodate different functions based on intra- and extracellular cues. One of the ER structures observed in plants is known as "organized smooth endoplasmic reticulum" (OSER), consisting of symmetrically stacked ER membrane arrays. In plants, these structures were first described in certain specialized tissues, e.g. the sieve elements of the phloem, and more recently in transgenic plants overexpressing ER membrane resident proteins. To date, much of the investigation of OSER focused on yeast and animal cells but research into plant OSER has started to grow. In this update, we give a succinct overview of research into the OSER phenomenon in plant cells with case studies highlighting both native and synthetic occurrences of OSER. We also assess the primary driving forces that trigger the formation of OSER, collating evidence from the literature to compare two competing theories for the origin of OSER: that OSER formation is initiated by oligomerizing protein accumulation in the ER membrane or that OSER is the result of ER membrane proliferation. This has long been a source of controversy in the field and here we suggest a way to integrate arguments from both sides into a single unifying theory. Finally, we discuss the potential biotechnological uses of OSER as a tool for the nascent plant synthetic biology field with possible applications as a synthetic microdomain for metabolic engineering and as an extensive membrane surface for synthetic chemistry or protein accumulation.
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Affiliation(s)
- Andras Sandor
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Mark D Fricker
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Verena Kriechbaumer
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Lee J Sweetlove
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
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10
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Nagano M, Ueda H, Fukao Y, Kawai-Yamada M, Hara-Nishimura I. Generation of Arabidopsis lines with a red fluorescent marker for endoplasmic reticulum using a tail-anchored protein cytochrome b5 -B. PLANT SIGNALING & BEHAVIOR 2020; 15:1790196. [PMID: 32633191 PMCID: PMC8550181 DOI: 10.1080/15592324.2020.1790196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/22/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
The endoplasmic reticulum (ER) is a multifunctional organelle that performs multiple cellular activities in eukaryotes. Visualizing ER using fluorescent proteins is a powerful method of analyzing its dynamics and to understand its functions. However, red fluorescent proteins with both an N-terminal signal peptide (SP) and a C-terminal ER retention tetrapeptide (HDEL) often cause mislocalization to vacuoles or extracellular spaces when they are constitutively expressed in Arabidopsis. To obtain a red fluorescent ER marker, we selected Arabidopsis cytochrome b5 -B (Cb5-B), a tail-anchored (TA) protein on the ER membrane. Its localization is determined by the transmembrane domain (TMD) and tail domain at the C-terminus. We fused the TMD and the tail domain of Cb5-B to the C-terminus of a red fluorescent protein, tdTomato (tdTomato-CTT). When tdTomato-CTT was constitutively expressed under the ubiquitin10 promoter in Arabidopsis, the fluorescent signal was exclusively detected at the ER by means of the reliable ER marker SP-GFP-HDEL. Therefore, tdTomato-CTT can accurately visualize the ER in stable Arabidopsis lines. Additionally, transient assays showed that tdTomato-CTT can also be used as an ER marker in onion, rice, and Nicotiana benthamiana. We believe that TA proteins could be used to generate various organellar membrane markers in plants.
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Affiliation(s)
- Minoru Nagano
- College of Life Sciences, Ritsumeikan University, Kusatsu, Japan
| | - Haruko Ueda
- Faculty of Science and Engineering, Konan University, Kobe, Japan
| | - Yoichiro Fukao
- College of Life Sciences, Ritsumeikan University, Kusatsu, Japan
| | - Maki Kawai-Yamada
- Graduate School of Science and Engineering, Saitama University, Saitama, Japan
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11
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Lin TW, Chen CC, Wu SM, Chang YC, Li YC, Su YW, Hsiao CD, Chang HY. Structural analysis of chloroplast tail-anchored membrane protein recognition by ArsA1. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 99:128-143. [PMID: 30891827 DOI: 10.1111/tpj.14316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 02/26/2019] [Accepted: 03/11/2019] [Indexed: 06/09/2023]
Abstract
In mammals and yeast, tail-anchored (TA) membrane proteins destined for the post-translational pathway are safely delivered to the endoplasmic reticulum (ER) membrane by a well-known targeting factor, TRC40/Get3. In contrast, the underlying mechanism for translocation of TA proteins in plants remains obscure. How this unique eukaryotic membrane-trafficking system correctly distinguishes different subsets of TA proteins destined for various organelles, including mitochondria, chloroplasts and the ER, is a key question of long standing. Here, we present crystal structures of algal ArsA1 (the Get3 homolog) in a distinct nucleotide-free open state and bound to adenylyl-imidodiphosphate. This approximately 80-kDa protein possesses a monomeric architecture, with two ATPase domains in a single polypeptide chain. It is capable of binding chloroplast (TOC34 and TOC159) and mitochondrial (TOM7) TA proteins based on features of its transmembrane domain as well as the regions immediately before and after the transmembrane domain. Several helices located above the TA-binding groove comprise the interlocking hook-like motif implicated by mutational analyses in TA substrate recognition. Our data provide insights into the molecular basis of the highly specific selectivity of interactions of algal ArsA1 with the correct sets of TA substrates before membrane targeting in plant cells.
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Affiliation(s)
- Tai-Wen Lin
- Molecular and Cell Biology, International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan
- Institute of Molecular Biology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - Chi-Chih Chen
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
- The Asia-Pacific Ocean Research Center, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
- Doctoral Degree Program in Marine Biotechnology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-Sen University, 70 Lien-Hai Road, Kaohsiung, 80424, Taiwan
| | - Shu-Mei Wu
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Yu-Ching Chang
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Yi-Chuan Li
- Molecular and Cell Biology, International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Wang Su
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Chwan-Deng Hsiao
- Molecular and Cell Biology, International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan
- Institute of Molecular Biology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
- Doctoral Degree Program in Marine Biotechnology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - Hsin-Yang Chang
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
- The Asia-Pacific Ocean Research Center, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-Sen University, 70 Lien-Hai Road, Kaohsiung, 80424, Taiwan
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12
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Teresinski HJ, Gidda SK, Nguyen TND, Howard NJM, Porter BK, Grimberg N, Smith MD, Andrews DW, Dyer JM, Mullen RT. An RK/ST C-Terminal Motif is Required for Targeting of OEP7.2 and a Subset of Other Arabidopsis Tail-Anchored Proteins to the Plastid Outer Envelope Membrane. PLANT & CELL PHYSIOLOGY 2019; 60:516-537. [PMID: 30521026 DOI: 10.1093/pcp/pcy234] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 12/03/2018] [Indexed: 06/09/2023]
Abstract
Tail-anchored (TA) proteins are a unique class of integral membrane proteins that possess a single C-terminal transmembrane domain and target post-translationally to the specific organelles at which they function. While significant advances have been made in recent years in elucidating the mechanisms and molecular targeting signals involved in the proper sorting of TA proteins, particularly to the endoplasmic reticulum and mitochondria, relatively little is known about the targeting of TA proteins to the plastid outer envelope. Here we show that several known or predicted plastid TA outer envelope proteins (OEPs) in Arabidopsis possess a C-terminal RK/ST sequence motif that serves as a conserved element of their plastid targeting signal. Evidence for this conclusion comes primarily from experiments with OEP7.2, which is a member of the Arabidopsis 7 kDa OEP family. We confirmed that OEP7.2 is localized to the plastid outer envelope and possesses a TA topology, and its C-terminal sequence (CTS), which includes the RK/ST motif, is essential for proper targeting to plastids. The CTS of OEP7.2 is functionally interchangeable with the CTSs of other TA OEPs that possess similar RK/ST motifs, but not with those that lack the motif. Further, a bioinformatics search based on a consensus sequence led to the identification of several new OEP TA proteins. Collectively, this study provides new insight into the mechanisms of TA protein sorting in plant cells, defines a new targeting signal element for a subset of TA OEPs and expands the number and repertoire of TA proteins at the plastid outer envelope.
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Affiliation(s)
- Howard J Teresinski
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Thuy N D Nguyen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Naomi J Marty Howard
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Brittany K Porter
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Nicholas Grimberg
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Matthew D Smith
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - David W Andrews
- Sunnybrook Research Institute and Departments of Biochemistry and Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - John M Dyer
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research Center, Maricopa, USA
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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Delfosse K, Wozny MR, Barton KA, Mathur N, Griffiths N, Mathur J. Plastid Envelope-Localized Proteins Exhibit a Stochastic Spatiotemporal Relationship to Stromules. FRONTIERS IN PLANT SCIENCE 2018; 9:754. [PMID: 29915611 PMCID: PMC5995270 DOI: 10.3389/fpls.2018.00754] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 05/16/2018] [Indexed: 05/13/2023]
Abstract
UNLABELLED Plastids in the viridiplantae sporadically form thin tubules called stromules that increase the interactive surface between the plastid and the surrounding cytoplasm. Several recent publications that report observations of certain proteins localizing to the extensions have then used the observations to suggest stromule-specific functions. The mechanisms by which specific localizations on these transient and sporadically formed extensions might occur remain unclear. Previous studies have yet to address the spatiotemporal relationship between a particular protein localization pattern and its distribution on an extended stromules and/or the plastid body. Here, we have used discrete protein patches found in several transgenic plants as fiducial markers to investigate this relationship. While we consider the inner plastid envelope-membrane localized protein patches of the GLUCOSE 6-PHOSPHATE/PHOSPHATE TRANSLOCATOR1 and the TRIOSE-PHOSPHATE/ PHOSPHATE TRANSLOCATOR 1 as artifacts of fluorescent fusion protein over-expression, stromule formation is not compromised in the respective stable transgenic lines that maintain normal growth and development. Our analysis of chloroplasts in the transgenic lines in the Arabidopsis Columbia background, and in the arc6 mutant, under stromule-inducing conditions shows that the possibility of finding a particular protein-enriched domain on an extended stromule or on a region of the main plastid body is stochastic. Our observations provide insights on the behavior of chloroplasts, the relationship between stromules and the plastid-body and strongly challenge claims of stromule-specific functions based solely upon protein localization to plastid extensions. ONE SENTENCE SUMMARY Observations of the spatiotemporal relationship between plastid envelope localized fluorescent protein fusions of two sugar-phosphate transporters and stromules suggest a stochastic rather than specific localization pattern that questions the idea of independent functions for stromules.
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14
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Zheng F, Cui X, Rivarola M, Gao T, Chang C, Dong CH. Molecular association of Arabidopsis RTH with its homolog RTE1 in regulating ethylene signaling. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:2821-2832. [PMID: 28541511 PMCID: PMC5853943 DOI: 10.1093/jxb/erx175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 04/21/2017] [Indexed: 05/29/2023]
Abstract
The plant hormone ethylene affects many biological processes during plant growth and development. Ethylene is perceived by ethylene receptors at the endoplasmic reticulum (ER) membrane. The ETR1 ethylene receptor is positively regulated by the transmembrane protein RTE1, which localizes to the ER and Golgi apparatus. The RTE1 gene family is conserved in animals, plants, and lower eukaryotes. In Arabidopsis, RTE1-HOMOLOG (RTH) is the only homolog of the Arabidopsis RTE1 gene family. The regulatory function of the Arabidopsis RTH in ethylene signaling and plant growth is largely unknown. The present study shows Arabidopsis RTH gene expression patterns, protein co-localization with the ER and Golgi apparatus, and the altered ethylene response phenotype when RTH is knocked out or overexpressed in Arabidopsis. Compared with rte1 mutants, rth mutants exhibit less sensitivity to exogenous ethylene, while RTH overexpression confers ethylene hypersensitivity. Genetic analyses indicate that Arabidopsis RTH might not directly regulate the ethylene receptors. RTH can physically interact with RTE1, and evidence supports that RTH might act via RTE1 in regulating ethylene responses and signaling. The present study advances our understanding of the regulatory function of the Arabidopsis RTE1 gene family members in ethylene signaling.
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Affiliation(s)
- Fangfang Zheng
- College of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - Xiankui Cui
- College of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - Maximo Rivarola
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Ting Gao
- College of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - Caren Chang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Chun-Hai Dong
- College of Life Sciences, Qingdao Agricultural University, Qingdao, China
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15
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Padgett LR, Arrizabalaga G, Sullivan WJ. Targeting of tail-anchored membrane proteins to subcellular organelles in Toxoplasma gondii. Traffic 2017; 18:149-158. [PMID: 27991712 DOI: 10.1111/tra.12464] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 12/12/2016] [Accepted: 12/12/2016] [Indexed: 12/20/2022]
Abstract
Proper protein localization is essential for critical cellular processes, including vesicle-mediated transport and protein translocation. Tail-anchored (TA) proteins are integrated into organellar membranes via the C-terminus, orienting the N-terminus towards the cytosol. Localization of TA proteins occurs posttranslationally and is governed by the C-terminus, which contains the integral transmembrane domain (TMD) and targeting sequence. Targeting of TA proteins is dependent on the hydrophobicity of the TMD as well as the length and composition of flanking amino acid sequences. We previously identified an unusual homologue of elongator protein, Elp3, in the apicomplexan parasite Toxoplasma gondii as a TA protein targeting the outer mitochondrial membrane. We sought to gain further insight into TA proteins and their targeting mechanisms using this early-branching eukaryote as a model. Our bioinformatics analysis uncovered 59 predicted TA proteins in Toxoplasma, 9 of which were selected for follow-up analyses based on representative features. We identified novel TA proteins that traffic to specific organelles in Toxoplasma, including the parasite endoplasmic reticulum, mitochondrion, and Golgi apparatus. Domain swap experiments elucidated that targeting of TA proteins to these specific organelles was strongly influenced by the TMD sequence, including charge of the flanking C-terminal sequence.
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Affiliation(s)
- Leah R Padgett
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Gustavo Arrizabalaga
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana
| | - William J Sullivan
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana
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16
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Vik D, Crocoll C, Andersen TG, Burow M, Halkier BA. CB5C affects the glucosinolate profile in Arabidopsis thaliana. PLANT SIGNALING & BEHAVIOR 2016; 11:e1160189. [PMID: 27454255 PMCID: PMC5022417 DOI: 10.1080/15592324.2016.1160189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 02/23/2016] [Accepted: 02/24/2016] [Indexed: 05/26/2023]
Abstract
Cytochrome b5 (CB5) proteins are small heme-binding proteins, that influence cytochrome P450 activity. While only one CB5 isoform is found in mammals, higher plants have several isoforms of these proteins. The roles of the many CB5 isoforms in plants remain unknown. We hypothesized that CB5 proteins support the cytochrome P450 enzymes of plant specialized metabolism and found CB5C from Arabidopsis thaliana to co-express with glucosinolate biosynthetic genes. We characterized the glucosinolate profiles of 2 T-DNA insertion mutants of CB5C, and found that long-chained aliphatic glucosinolates were reduced in one of the mutant lines - a phenotype that was exaggerated upon methyl-jasmonate treatment. These results support the hypothesis, that CB5C influences glucosinolate biosynthesis, however, the mode of action remains unknown. Furthermore, the mutants differed in their biomass response to methyl jasmonate treatment. Thereby, our results highlight the varying effects of T-DNA insertion sites, as the 2 analyzed alleles show different phenotypes.
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Affiliation(s)
- Daniel Vik
- Department of Plant and Environmental Sciences, DynaMo Center of Excellence & Copenhagen Plant Science Center, University of Copenhagen, Denmark
| | - Christoph Crocoll
- Department of Plant and Environmental Sciences, DynaMo Center of Excellence & Copenhagen Plant Science Center, University of Copenhagen, Denmark
| | | | - Meike Burow
- Department of Plant and Environmental Sciences, DynaMo Center of Excellence & Copenhagen Plant Science Center, University of Copenhagen, Denmark
| | - Barbara Ann Halkier
- Department of Plant and Environmental Sciences, DynaMo Center of Excellence & Copenhagen Plant Science Center, University of Copenhagen, Denmark
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17
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Pedrazzini E, Caprera A, Fojadelli I, Stella A, Rocchetti A, Bassin B, Martinoia E, Vitale A. The Arabidopsis tonoplast is almost devoid of glycoproteins with complex N-glycans, unlike the rat lysosomal membrane. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:1769-81. [PMID: 26748395 PMCID: PMC4783361 DOI: 10.1093/jxb/erv567] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The distribution of the N-glycoproteome in integral membrane proteins of the vacuolar membrane (tonoplast) or the plasma membrane of Arabidopsis thaliana and, for further comparison, of the Rattus norvegicus lysosomal and plasma membranes, was analyzed. In silico analysis showed that potential N-glycosylation sites are much less frequent in tonoplast proteins. Biochemical analysis of Arabidopsis subcellular fractions with the lectin concanavalin A, which recognizes mainly unmodified N-glycans, or with antiserum against Golgi-modified N-glycans confirmed the in silico results and showed that, unlike the plant plasma membrane, the tonoplast is almost or totally devoid of N-glycoproteins with Golgi-modified glycans. Lysosomes share with vacuoles the hydrolytic functions and the position along the secretory pathway; however, our results indicate that their membranes had a divergent evolution. We propose that protection against the luminal hydrolases that are abundant in inner hydrolytic compartments, which seems to have been achieved in many lysosomal membrane proteins by extensive N-glycosylation of the luminal domains, has instead been obtained in the vast majority of tonoplast proteins by limiting the length of such domains.
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Affiliation(s)
| | | | | | | | | | - Barbara Bassin
- Institute of Plant Biology, University of Zurich, Zurich, Switzerland
| | - Enrico Martinoia
- Institute of Plant Biology, University of Zurich, Zurich, Switzerland
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18
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Nagano M, Ishikawa T, Ogawa Y, Iwabuchi M, Nakasone A, Shimamoto K, Uchimiya H, Kawai-Yamada M. Arabidopsis Bax inhibitor-1 promotes sphingolipid synthesis during cold stress by interacting with ceramide-modifying enzymes. PLANTA 2014; 240:77-89. [PMID: 24687220 DOI: 10.1007/s00425-014-2065-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Accepted: 03/13/2014] [Indexed: 05/04/2023]
Abstract
Bax inhibitor-1 (BI-1) is a widely conserved cell death suppressor localized in the endoplasmic reticulum membrane. Our previous results revealed that Arabidopsis BI-1 (AtBI-1) interacts with not only Arabidopsis cytochrome b 5 (Cb5), an electron transfer protein, but also a Cb5-like domain (Cb5LD)-containing protein, Saccharomyces cerevisiae fatty acid 2-hydroxylase 1, which 2-hydroxylates sphingolipid fatty acids. We have now found that AtBI-1 binds Arabidopsis sphingolipid Δ8 long-chain base (LCB) desaturases AtSLD1 and AtSLD2, which are Cb5LD-containing proteins. The expression of both AtBI-1 and AtSLD1 was increased by cold exposure. However, different phenotypes were observed in response to cold treatment between an atbi-1 mutant and a sld1sld2 double mutant. To elucidate the reasons behind the difference, we analyzed sphingolipids and found that unsaturated LCBs in atbi-1 were not altered compared to wild type, whereas almost all LCBs in sld1sld2 were saturated, suggesting that AtBI-1 may not be necessary for the desaturation of LCBs. On the other hand, the sphingolipid content in wild type increased in response to low temperature, whereas total sphingolipid levels in atbi-1 were unaltered. In addition, the ceramide-modifying enzymes AtFAH1, sphingolipid base hydroxylase 2 (AtSBH2), acyl lipid desaturase 2 (AtADS2) and AtSLD1 were highly expressed under cold stress, and all are likely to be related to AtBI-1 function. These findings suggest that AtBI-1 contributes to synthesis of sphingolipids during cold stress by interacting with AtSLD1, AtFAH1, AtSBH2 and AtADS2.
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Affiliation(s)
- Minoru Nagano
- Graduate School of Biological Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, 630-0192, Japan
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19
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Chang J, Clay JM, Chang C. Association of cytochrome b5 with ETR1 ethylene receptor signaling through RTE1 in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:558-67. [PMID: 24635651 PMCID: PMC4040253 DOI: 10.1111/tpj.12401] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 11/26/2013] [Accepted: 11/29/2013] [Indexed: 05/20/2023]
Abstract
Ethylene plays important roles in plant growth, development and stress responses, and is perceived by a family of receptors that repress ethylene responses when ethylene is absent. Repression by the ethylene receptor ETR1 depends on an integral membrane protein, REVERSION TO ETHYLENE SENSITIVITY1 (RTE1), which acts upstream of ETR1 in the endoplasmic reticulum (ER) membrane and Golgi apparatus. To investigate RTE1 function, we screened for RTE1-interacting proteins using the yeast split-ubiquitin assay, which yielded the ER-localized cytochrome b(5) (Cb5) isoform D. Cb5s are small hemoproteins that perform electron transfer reactions in all eukaryotes, but their roles in plants are relatively uncharacterized. Using bimolecular fluorescence complementation (BiFC), we found that all four ER-localized Arabidopsis Cb5 isoforms (AtCb5–B, -C, -D and -E) interact with RTE1 in plant cells. In support of this interaction, atcb5 mutants exhibited phenotypic parallels with rte1 mutants in Arabidopsis. Phenotypes included partial suppression of etr1–2 ethylene insensitivity, and no suppression of RTE1-independent ethylene receptor isoforms. The single loss-of-function mutants atcb5–b, -c and -d appeared similar to the wild-type, but double mutant combinations displayed slight ethylene hypersensitivity. Over-expression of AtCb5–D conferred reduced ethylene sensitivity similar to that conferred by RTE1 over-expression, and genetic analyses suggested that AtCb5–D acts upstream of RTE1 in the ethylene response. These findings suggest an unexpected role for Cb5, in which Cb5 and RTE1 are functional partners in promoting ETR1-mediated repression of ethylene signaling.
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Affiliation(s)
| | | | - Caren Chang
- Corresponding author: Caren Chang, Department of Cell Biology and Molecular Genetics, Bioscience Research Building, Bldg 413, University of Maryland, College Park, MD 20742, USA, Phone: 301-405-1643, Fax: 301-314-1248,
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20
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Marty NJ, Teresinski HJ, Hwang YT, Clendening EA, Gidda SK, Sliwinska E, Zhang D, Miernyk JA, Brito GC, Andrews DW, Dyer JM, Mullen RT. New insights into the targeting of a subset of tail-anchored proteins to the outer mitochondrial membrane. FRONTIERS IN PLANT SCIENCE 2014; 5:426. [PMID: 25237314 PMCID: PMC4154396 DOI: 10.3389/fpls.2014.00426] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/12/2014] [Indexed: 05/21/2023]
Abstract
Tail-anchored (TA) proteins are a unique class of functionally diverse membrane proteins defined by their single C-terminal membrane-spanning domain and their ability to insert post-translationally into specific organelles with an Ncytoplasm-Corganelle interior orientation. The molecular mechanisms by which TA proteins are sorted to the proper organelles are not well-understood. Herein we present results indicating that a dibasic targeting motif (i.e., -R-R/K/H-X({X≠E})) identified previously in the C terminus of the mitochondrial isoform of the TA protein cytochrome b 5, also exists in many other A. thaliana outer mitochondrial membrane (OMM)-TA proteins. This motif is conspicuously absent, however, in all but one of the TA protein subunits of the translocon at the outer membrane of mitochondria (TOM), suggesting that these two groups of proteins utilize distinct biogenetic pathways. Consistent with this premise, we show that the TA sequences of the dibasic-containing proteins are both necessary and sufficient for targeting to mitochondria, and are interchangeable, while the TA regions of TOM proteins lacking a dibasic motif are necessary, but not sufficient for localization, and cannot be functionally exchanged. We also present results from a comprehensive mutational analysis of the dibasic motif and surrounding sequences that not only greatly expands the functional definition and context-dependent properties of this targeting signal, but also led to the identification of other novel putative OMM-TA proteins. Collectively, these results provide important insight to the complexity of the targeting pathways involved in the biogenesis of OMM-TA proteins and help define a consensus targeting motif that is utilized by at least a subset of these proteins.
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Affiliation(s)
- Naomi J. Marty
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Howard J. Teresinski
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Yeen Ting Hwang
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Eric A. Clendening
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Elwira Sliwinska
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
- Department of Plant Genetics, Physiology and Biotechnology, University of Technology and Life Sciences in BydgoszczBydgoszcz, Poland
| | - Daiyuan Zhang
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research CenterMaricopa, AZ, USA
| | - Ján A. Miernyk
- United States Department of Agriculture, Agricultural Research Service, Plant Genetics Research Unit, University of MissouriColumbia, MO, USA
| | - Glauber C. Brito
- Instituto do Cancer do Estado de Sao Paulo, Fundacao Faculdade de Medicina, Universidade de Sao PauloSao Paulo, Brazil
| | - David W. Andrews
- Sunnybrook Research Institute and Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - John M. Dyer
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research CenterMaricopa, AZ, USA
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
- *Correspondence: Robert T. Mullen, Department of Molecular and Cellular, Biology, University of Guelph, Room 4470 Science Complex, 488 Gordon Street, Guelph, ON N1G 2W1, Canada e-mail:
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21
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Virgili-López G, Langhans M, Bubeck J, Pedrazzini E, Gouzerh G, Neuhaus JM, Robinson DG, Vitale A. Comparison of membrane targeting strategies for the accumulation of the human immunodeficiency virus p24 protein in transgenic tobacco. Int J Mol Sci 2013; 14:13241-65. [PMID: 23803657 PMCID: PMC3742185 DOI: 10.3390/ijms140713241] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 05/28/2013] [Accepted: 06/17/2013] [Indexed: 01/09/2023] Open
Abstract
Membrane anchorage was tested as a strategy to accumulate recombinant proteins in transgenic plants. Transmembrane domains of different lengths and topology were fused to the cytosolic HIV antigen p24, to promote endoplasmic reticulum (ER) residence or traffic to distal compartments of the secretory pathway in transgenic tobacco. Fusions to a domain of the maize seed storage protein γ-zein were also expressed, as a reference strategy that leads to very high stability via the formation of large polymers in the ER lumen. Although all the membrane anchored constructs were less stable compared to the zein fusions, residence at the ER membrane either as a type I fusion (where the p24 sequence is luminal) or a tail-anchored fusion (where the p24 sequence is cytosolic) resulted in much higher stability than delivery to the plasma membrane or intermediate traffic compartments. Delivery to the tonoplast was never observed. The inclusion of a thrombin cleavage site allowed for the quantitative in vitro recovery of p24 from all constructs. These results point to the ER as suitable compartment for the accumulation of membrane-anchored recombinant proteins in plants.
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Affiliation(s)
- Goretti Virgili-López
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg D-69120, Germany; E-Mails: (G.V.-L.); (M.L.); (J.B.)
- Institute of Agricultural Biology and Biotechnology, National Research Council (CNR), via Bassini 15, Milano 20133, Italy; E-Mail:
- Laboratory of Cell and Molecular Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchâtel CH-2000, Switzerland; E-Mail:
| | - Markus Langhans
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg D-69120, Germany; E-Mails: (G.V.-L.); (M.L.); (J.B.)
| | - Julia Bubeck
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg D-69120, Germany; E-Mails: (G.V.-L.); (M.L.); (J.B.)
| | - Emanuela Pedrazzini
- Institute of Agricultural Biology and Biotechnology, National Research Council (CNR), via Bassini 15, Milano 20133, Italy; E-Mail:
| | - Guillaume Gouzerh
- Laboratory of Cell and Molecular Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchâtel CH-2000, Switzerland; E-Mail:
| | - Jean-Marc Neuhaus
- Laboratory of Cell and Molecular Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchâtel CH-2000, Switzerland; E-Mail:
| | - David G. Robinson
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg D-69120, Germany; E-Mails: (G.V.-L.); (M.L.); (J.B.)
| | - Alessandro Vitale
- Institute of Agricultural Biology and Biotechnology, National Research Council (CNR), via Bassini 15, Milano 20133, Italy; E-Mail:
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22
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Formighieri C, Cazzaniga S, Kuras R, Bassi R. Biogenesis of photosynthetic complexes in the chloroplast of Chlamydomonas reinhardtii requires ARSA1, a homolog of prokaryotic arsenite transporter and eukaryotic TRC40 for guided entry of tail-anchored proteins. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:850-61. [PMID: 23167510 DOI: 10.1111/tpj.12077] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 11/13/2012] [Accepted: 11/15/2012] [Indexed: 05/08/2023]
Abstract
as1, for antenna size mutant 1, was obtained by insertion mutagenesis of the unicellular green alga Chlamydomonas reinhardtii. This strain has a low chlorophyll content, 8% with respect to the wild type, and displays a general reduction in thylakoid polypeptides. The mutant was found to carry an insertion into a homologous gene, prokaryotic arsenite transporter (ARSA), whose yeast and mammal counterparts were found to be involved in the targeting of tail-anchored (TA) proteins to cytosol-exposed membranes, essential for several cellular functions. Here we present the characterization in a photosynthetic organism of an insertion mutant in an ARSA-homolog gene. The ARSA1 protein was found to be localized in the cytosol, and yet its absence in as1 leads to a small chloroplast and a strongly decreased chlorophyll content per cell. ARSA1 appears to be required for optimal biogenesis of photosynthetic complexes because of its involvement in the accumulation of TOC34, an essential component of the outer chloroplast membrane translocon (TOC) complex, which, in turn, catalyzes the import of nucleus-encoded precursor polypeptides into the chloroplast. Remarkably, the effect of the mutation appears to be restricted to biogenesis of chlorophyll-binding polypeptides and is not compensated by the other ARSA homolog encoded by the C. reinhardtii genome, implying a non-redundant function.
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Affiliation(s)
- Cinzia Formighieri
- Dipartimento di Biotecnologie, Università di Verona, 15, Strada Le Grazie, I-37134 Verona, Italy
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23
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Nagano M, Uchimiya H, Kawai-Yamada M. Plant sphingolipid fatty acid 2-hydroxylases have unique characters unlike their animal and fungus counterparts. PLANT SIGNALING & BEHAVIOR 2012; 7:1388-1392. [PMID: 22918503 PMCID: PMC3548854 DOI: 10.4161/psb.21825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
2-Hydroxy fatty acids mainly contained in sphingolipids are synthesized by a sphingolipid fatty acid 2-hydroxylase (FAH). Recently, two FAH homologs in Arabidopsis thaliana (AtFAH1 and AtFAH2), without any cytochrome b₅(Cb5)-like domains, which are essential for the function of Saccharomyces cerevisiae and mammalian FAH, were identified and both AtFAHs were shown to be activated by the interaction with Cb5. In this study, we compared FAHs of various plants, animals and fungi. Interestingly, only plants had two FAH homologs and none of plant FAHs had any Cb5-like domains. In addition, we showed from the interaction and expression analyses that AtFAHs interacted with multiple Cb5s probably in various tissues. Thus, plant FAHs may have evolved unlike animal and fungus FAHs.
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Affiliation(s)
- Minoru Nagano
- Graduate School of Biological Science; Nara Institute of Science and Technology; Takayama, Ikoma, Japan
| | - Hirofumi Uchimiya
- Institute for Environmental Science and Technology; Saitama University; Sakura-ku, Saitama, Japan
| | - Maki Kawai-Yamada
- Institute for Environmental Science and Technology; Saitama University; Sakura-ku, Saitama, Japan
- Graduate School of Science and Engineering; Saitama University; Sakura-ku, Saitama, Japan
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24
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Li Y, Li LL, Fan RC, Peng CC, Sun HL, Zhu SY, Wang XF, Zhang LY, Zhang DP. Arabidopsis sucrose transporter SUT4 interacts with cytochrome b5-2 to regulate seed germination in response to sucrose and glucose. MOLECULAR PLANT 2012; 5:1029-41. [PMID: 22311778 DOI: 10.1093/mp/sss001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
It remains unknown whether a sucrose transporter mediates sugar signaling. Here, we report that the Arabidopsis (Arabidopsis thaliana) sucrose transporter SUT4 interacts with five members of the Arabidopsis cytochrome b5 (Cyb5) family, and sucrose represses the interaction between SUT4 and a Cyb5 member Cyb5-2/A. We observed that down-regulation of SUT4 and three cytochrome b5 members (Cyb5-2, Cyb5-4, and Cyb5-6) confers the sucrose- and glucose-insensitive phenotypes in the sucrose/glucose-induced inhibition of seed germination. The sut4 cyb5-2 double mutant displays slightly stronger sucrose/glucose-insensitive phenotypes than either the sut4 or cyb5-2 single mutant. We showed that the SUT4/Cyb5-2-mediated signaling in the sucrose/glucose-induced inhibition of seed germination does not require ABA or the currently known ABI2/ABI4/ABI5-mediated signaling pathway(s). These data provide evidence that the sucrose transporter SUT4 interacts with Cyb5 to positively mediate sucrose and glucose signaling in the sucrose/glucose-induced inhibition of seed germination.
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Affiliation(s)
- Yan Li
- College of Biological Sciences, China Agricultural University, Beijing 100094, China
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25
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Sun F, Carrie C, Law S, Murcha MW, Zhang R, Law YS, Suen PK, Whelan J, Lim BL. AtPAP2 is a tail-anchored protein in the outer membrane of chloroplasts and mitochondria. PLANT SIGNALING & BEHAVIOR 2012; 7:927-32. [PMID: 22751362 PMCID: PMC3474687 DOI: 10.4161/psb.20769] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
To date, Arabidopsis purple acid phosphatase 2 (AtPAP2) is the only known plant protein that is dual-targeted to chloroplasts and mitochondria by a C-terminal targeting signal. Using in vitro organelle import and green fluorescence protein (GFP) localization assays, we showed that AtPAP2 is located on, but not imported across the outer membrane (OM) of chloroplasts and mitochondria and exposed its N-terminal enzymatic domain to the cytosol. It was also found that a short stretch of 30 amino acids (a.a.) at the C-terminal region (a.a. 615-644) that contains a stretch of 18 hydrophobic residues, a WYAK motif and 8 hydrophilic residues is sufficient for dual-targeting. Mutation of WYAK to WYAE had no effect on dual-targeting ability suggesting that the charge within this flanking region alone is not an important determinant for dual-targeting.
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Affiliation(s)
- Feng Sun
- School of Biological Sciences; The University of Hong Kong; Pokfulam, Hong Kong, China
| | - Chris Carrie
- Australian Research Council Centre of Excellence in Plant Energy Biology; University of Western Australia; Crawley, WA Australia
| | - Simon Law
- Australian Research Council Centre of Excellence in Plant Energy Biology; University of Western Australia; Crawley, WA Australia
| | - Monika W. Murcha
- Australian Research Council Centre of Excellence in Plant Energy Biology; University of Western Australia; Crawley, WA Australia
| | - Renshan Zhang
- School of Biological Sciences; The University of Hong Kong; Pokfulam, Hong Kong, China
| | - Yee Song Law
- School of Biological Sciences; The University of Hong Kong; Pokfulam, Hong Kong, China
| | - Pui Kit Suen
- School of Biological Sciences; The University of Hong Kong; Pokfulam, Hong Kong, China
| | - James Whelan
- Australian Research Council Centre of Excellence in Plant Energy Biology; University of Western Australia; Crawley, WA Australia
| | - Boon Leong Lim
- School of Biological Sciences; The University of Hong Kong; Pokfulam, Hong Kong, China
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26
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A cytochrome b5-containing plastid-located fatty acid desaturase from Chlamydomonas reinhardtii. EUKARYOTIC CELL 2012; 11:856-63. [PMID: 22562471 DOI: 10.1128/ec.00079-12] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Monogalactosyldiacylglycerol (MGDG) in Chlamydomonas reinhardtii and other green algae contains hexadeca-4,7,10,13-tetraenoic acid (16:4) in the glycerol sn-2 position. While many genes necessary for the introduction of acyl chain double bonds have been functionally characterized, the Δ4-desaturase remained unknown. Using a phylogenetic comparison, a candidate gene encoding the MGDG-specific Δ4-desaturase from Chlamydomonas (CrΔ4FAD) was identified. CrΔ4FAD shows all characteristic features of a membrane-bound desaturase, including three histidine boxes and a transit peptide for chloroplast targeting. But it also has an N-terminal cytochrome b(5) domain, distinguishing it from other known plastid desaturases. Cytochrome b(5) is the primary electron donor for endoplasmic reticulum (ER) desaturases and is often fused to the desaturase domain in desaturases modifying the carboxyl end of the acyl group. Difference absorbance spectra of the recombinant cytochrome b(5) domain of CrΔ4FAD showed that it is functional in vitro. Green fluorescent protein fusions of CrΔ4FAD localized to the plastid envelope in Chlamydomonas. Interestingly, overproduction of CrΔ4FAD in Chlamydomonas not only increased levels of 16:4 acyl groups in cell extracts but specifically increased the total amount of MGDG. Vice versa, the amount of MGDG was lowered in lines with reduced levels of CrΔ4FAD. These data suggest a link between MGDG molecular species composition and galactolipid abundance in the alga, as well as a specific function for this fatty acid in MGDG.
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Cytosolic events involved in chloroplast protein targeting. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:245-52. [PMID: 22450030 DOI: 10.1016/j.bbamcr.2012.03.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 02/24/2012] [Accepted: 03/08/2012] [Indexed: 12/12/2022]
Abstract
Chloroplasts are unique organelles that are responsible for photosynthesis. Although chloroplasts contain their own genome, the majority of chloroplast proteins are encoded by the nuclear genome. These proteins are transported to the chloroplasts after translation in the cytosol. Chloroplasts contain three membrane systems (outer/inner envelope and thylakoid membranes) that subdivide the interior into three soluble compartments known as the intermembrane space, stroma, and thylakoid lumen. Several targeting mechanisms are required to deliver proteins to the correct chloroplast membrane or soluble compartment. These mechanisms have been extensively studied using purified chloroplasts in vitro. Prior to targeting these proteins to the various compartments of the chloroplast, they must be correctly sorted in the cytosol. To date, it is not clear how these proteins are sorted in the cytosol and then targeted to the chloroplasts. Recently, the cytosolic carrier protein AKR2 and its associated cofactor Hsp17.8 for outer envelope membrane proteins of chloroplasts were identified. Additionally, a mechanism for controlling unimported plastid precursors in the cytosol has been discovered. This review will mainly focus on recent findings concerning the possible cytosolic events that occur prior to protein targeting to the chloroplasts. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
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Kumar R, Tran LSP, Neelakandan AK, Nguyen HT. Higher plant cytochrome b5 polypeptides modulate fatty acid desaturation. PLoS One 2012; 7:e31370. [PMID: 22384013 PMCID: PMC3285619 DOI: 10.1371/journal.pone.0031370] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 01/09/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Synthesis of polyunsaturated fatty acids (PUFAs) in the endoplasmic reticulum of plants typically involves the fatty acid desaturases FAD2 and FAD3, which use cytochrome b(5) (Cb5) as an electron donor. Higher plants are reported to have multiple isoforms of Cb5, in contrast to a single Cb5 in mammals and yeast. Despite the wealth of information available on the roles of FAD2 and FAD3 in PUFA synthesis, information regarding the contributions of various Cb5 isoforms in desaturase-mediated reactions is limited. RESULTS The present functional characterization of Cb5 polypeptides revealed that all Arabidopsis Cb5 isoforms are not similarly efficient in ω-6 desaturation, as evidenced by significant variation in their product outcomes in yeast-based functional assays. On the other hand, characterization of Cb5 polypeptides of soybean (Glycine max) suggested that similar ω-6 desaturation efficiencies were shared by various isoforms. With regard to ω-3 desaturation, certain Cb5 genes of both Arabidopsis and soybean were shown to facilitate the accumulation of more desaturation products than others when co-expressed with their native FAD3. Additionally, similar trends of differential desaturation product accumulation were also observed with most Cb5 genes of both soybean and Arabidopsis even if co-expressed with non-native FAD3. CONCLUSIONS The present study reports the first description of the differential nature of the Cb5 genes of higher plants in fatty acid desaturation and further suggests that ω-3/ω-6 desaturation product outcome is determined by the nature of both the Cb5 isoform and the fatty acid desaturases.
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Affiliation(s)
- Rajesh Kumar
- Division of Plant Sciences and National Center for Soybean Biotechnology, University of Missouri, Columbia, Missouri, United States of America
| | - Lam-Son Phan Tran
- Division of Plant Sciences and National Center for Soybean Biotechnology, University of Missouri, Columbia, Missouri, United States of America
| | - Anjanasree K. Neelakandan
- Division of Plant Sciences and National Center for Soybean Biotechnology, University of Missouri, Columbia, Missouri, United States of America
| | - Henry T. Nguyen
- Division of Plant Sciences and National Center for Soybean Biotechnology, University of Missouri, Columbia, Missouri, United States of America
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Lee J, Lee H, Kim J, Lee S, Kim DH, Kim S, Hwang I. Both the hydrophobicity and a positively charged region flanking the C-terminal region of the transmembrane domain of signal-anchored proteins play critical roles in determining their targeting specificity to the endoplasmic reticulum or endosymbiotic organelles in Arabidopsis cells. THE PLANT CELL 2011; 23:1588-607. [PMID: 21515817 PMCID: PMC3101543 DOI: 10.1105/tpc.110.082230] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2010] [Revised: 03/30/2011] [Accepted: 04/06/2011] [Indexed: 05/20/2023]
Abstract
Proteins localized to various cellular and subcellular membranes play pivotal roles in numerous cellular activities. Accordingly, in eukaryotic cells, the biogenesis of organellar proteins is an essential process requiring their correct localization among various cellular and subcellular membranes. Localization of these proteins is determined by either cotranslational or posttranslational mechanisms, depending on the final destination. However, it is not fully understood how the targeting specificity of membrane proteins is determined in plant cells. Here, we investigate the mechanism by which signal-anchored (SA) proteins are differentially targeted to the endoplasmic reticulum (ER) or endosymbiotic organelles using in vivo targeting, subcellular fractionation, and bioinformatics approaches. For targeting SA proteins to endosymbiotic organelles, the C-terminal positively charged region (CPR) flanking the transmembrane domain (TMD) is necessary but not sufficient. The hydrophobicity of the TMD in CPR-containing proteins also plays a critical role in determining targeting specificity; TMDs with a hydrophobicity value >0.4 on the Wimley and White scale are targeted primarily to the ER, whereas TMDs with lower values are targeted to endosymbiotic organelles. Based on these data, we propose that the CPR and the hydrophobicity of the TMD play a critical role in determining the targeting specificity between the ER and endosymbiotic organelles.
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Affiliation(s)
- Junho Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Hyunkyung Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Jinho Kim
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Sumin Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Dae Heon Kim
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Sanguk Kim
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Inhwan Hwang
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
- Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
- Address correspondence to
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Borgese N, Fasana E. Targeting pathways of C-tail-anchored proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:937-46. [DOI: 10.1016/j.bbamem.2010.07.010] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 07/09/2010] [Accepted: 07/10/2010] [Indexed: 10/19/2022]
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Abell BM, Mullen RT. Tail-anchored membrane proteins: exploring the complex diversity of tail-anchored-protein targeting in plant cells. PLANT CELL REPORTS 2011; 30:137-51. [PMID: 20878326 DOI: 10.1007/s00299-010-0925-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 09/14/2010] [Indexed: 05/24/2023]
Abstract
Tail-anchored (TA) proteins are special class of integral membrane proteins that in recent years have received a considerable amount of attention due to their diverse cellular functions and unique targeting and insertion mechanisms. Defined by the presence of a single, hydrophobic membrane-spanning domain at or near their C terminus, TA proteins must be inserted into membranes post-translationally and are orientated such that their larger N-terminal domain (most often the functional domain) faces the cytosol, while their shorter C-terminal domain faces the interior of the organelle. The C-terminal domain of TA proteins also usually contains the information responsible for their selective targeting to the proper subcellular membrane, a process that, based primarily on studies with yeasts and mammals, appears to be highly complex due to the presence of multiple pathways. Within this context, we discuss here the biogenesis of plant TA proteins and the potential for hundreds of new TA proteins identified via bioinformatics screens to contribute to the already remarkable number of roles that this class of membrane proteins participates in throughout plant growth and development.
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Affiliation(s)
- Ben M Abell
- Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield, UK.
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Obembe OO, Popoola JO, Leelavathi S, Reddy SV. Advances in plant molecular farming. Biotechnol Adv 2010; 29:210-22. [PMID: 21115109 DOI: 10.1016/j.biotechadv.2010.11.004] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 11/12/2010] [Accepted: 11/12/2010] [Indexed: 01/01/2023]
Abstract
Plant molecular farming (PMF) is a new branch of plant biotechnology, where plants are engineered to produce recombinant pharmaceutical and industrial proteins in large quantities. As an emerging subdivision of the biopharmaceutical industry, PMF is still trying to gain comparable social acceptance as the already established production systems that produce these high valued proteins in microbial, yeast, or mammalian expression systems. This article reviews the various cost-effective technologies and strategies, which are being developed to improve yield and quality of the plant-derived pharmaceuticals, thereby making plant-based production system suitable alternatives to the existing systems. It also attempts to overview the different novel plant-derived pharmaceuticals and non-pharmaceutical protein products that are at various stages of clinical development or commercialization. It then discusses the biosafety and regulatory issues, which are crucial (if strictly adhered to) to eliminating potential health and environmental risks, which in turn is necessary to earning favorable public perception, thus ensuring the success of the industry.
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Affiliation(s)
- Olawole O Obembe
- Department of Biological Sciences, Covenant University, PMB 1023 Ota, Ogun State, Nigeria.
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Bohnsack MT, Schleiff E. The evolution of protein targeting and translocation systems. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:1115-30. [DOI: 10.1016/j.bbamcr.2010.06.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 05/26/2010] [Accepted: 06/11/2010] [Indexed: 11/28/2022]
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Ikeyama Y, Tasaka M, Fukaki H. RLF, a cytochrome b(5)-like heme/steroid binding domain protein, controls lateral root formation independently of ARF7/19-mediated auxin signaling in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:865-75. [PMID: 20230485 DOI: 10.1111/j.1365-313x.2010.04199.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Lateral root (LR) formation is important for the establishment of root architecture in higher plants. Recent studies have revealed that LR formation is regulated by an auxin signaling pathway that depends on auxin response factors ARF7 and ARF19, and auxin/indole-3-acetic acid (Aux/IAA) proteins including SOLITARY-ROOT (SLR)/IAA14. To understand the molecular mechanisms of LR formation, we isolated a recessive mutant rlf (reduced lateral root formation) in Arabidopsis thaliana. The rlf-1 mutant showed reduction of not only emerged LRs but also LR primordia. Analyses using cell-cycle markers indicated that the rlf-1 mutation inhibits the first pericycle cell divisions involved in LR initiation. The rlf-1 mutation did not affect auxin-induced root growth inhibition but did affect LR formation over a wide range of auxin concentrations. However, the rlf-1 mutation had almost no effect on auxin-inducible expression of LATERAL ORGAN BOUNDARIES-DOMAIN16/ASYMMETRIC LEAVES2-LIKE18 (LBD16/ASL18) and LBD29/ASL16 genes, which are downstream targets of ARF7/19 for LR formation. These results indicate that ARF7/19-mediated auxin signaling is not blocked by the rlf-1 mutation. We found that the RLF gene encodes At5g09680, a protein with a cytochrome b(5)-like heme/steroid binding domain. RLF is ubiquitously expressed in almost all organs, and the protein localizes in the cytosol. These results, together with analysis of the genetic interaction between the rlf-1 and arf7/19 mutations, indicate that RLF is a cytosolic protein that positively controls the early cell divisions involved in LR initiation, independent of ARF7/19-mediated auxin signaling.
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Affiliation(s)
- Yoshifumi Ikeyama
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan
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35
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Dhanoa PK, Richardson LGL, Smith MD, Gidda SK, Henderson MPA, Andrews DW, Mullen RT. Distinct pathways mediate the sorting of tail-anchored proteins to the plastid outer envelope. PLoS One 2010; 5:e10098. [PMID: 20418952 PMCID: PMC2854689 DOI: 10.1371/journal.pone.0010098] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 03/11/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Tail-anchored (TA) proteins are a distinct class of membrane proteins that are sorted post-translationally to various organelles and function in a number of important cellular processes, including redox reactions, vesicular trafficking and protein translocation. While the molecular targeting signals and pathways responsible for sorting TA proteins to their correct intracellular destinations in yeasts and mammals have begun to be characterized, relatively little is known about TA protein biogenesis in plant cells, especially for those sorted to the plastid outer envelope. METHODOLOGY/PRINCIPAL FINDINGS Here we investigated the biogenesis of three plastid TA proteins, including the 33-kDa and 34-kDa GTPases of the translocon at the outer envelope of chloroplasts (Toc33 and Toc34) and a novel 9-kDa protein of unknown function that we define here as an outer envelope TA protein (OEP9). Using a combination of in vivo and in vitro assays we show that OEP9 utilizes a different sorting pathway than that used by Toc33 and Toc34. For instance, while all three TA proteins interact with the cytosolic OEP chaperone/receptor, AKR2A, the plastid targeting information within OEP9 is distinct from that within Toc33 and Toc34. Toc33 and Toc34 also appear to differ from OEP9 in that their insertion is dependent on themselves and the unique lipid composition of the plastid outer envelope. By contrast, the insertion of OEP9 into the plastid outer envelope occurs in a proteinaceous-dependent, but Toc33/34-independent manner and membrane lipids appear to serve primarily to facilitate normal thermodynamic integration of this TA protein. CONCLUSIONS/SIGNIFICANCE Collectively, the results provide evidence in support of at least two sorting pathways for plastid TA outer envelope proteins and shed light on not only the complex diversity of pathways involved in the targeting and insertion of proteins into plastids, but also the molecular mechanisms that underlie the delivery of TA proteins to their proper intracellular locations in general.
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Affiliation(s)
- Preetinder K. Dhanoa
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Lynn G. L. Richardson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Matthew D. Smith
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Matthew P. A. Henderson
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - David W. Andrews
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- * E-mail:
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Kriechbaumer V, Shaw R, Mukherjee J, Bowsher CG, Harrison AM, Abell BM. Subcellular distribution of tail-anchored proteins in Arabidopsis. Traffic 2009; 10:1753-64. [PMID: 19843281 DOI: 10.1111/j.1600-0854.2009.00991.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Tail-anchored (TA) proteins function in key cellular processes in eukaryotic cells, such as vesicle trafficking, protein translocation and regulation of transcription. They anchor to internal cell membranes by a C-terminal transmembrane domain, which also serves as a targeting sequence. Targeting occurs post-translationally, via pathways that are specific to the precursor, which makes TA proteins a model system for investigating post-translational protein targeting. Bioinformatics approaches have previously been used to identify potential TA proteins in yeast and humans, yet little is known about TA proteins in plants. The identification of plant TA proteins is important for extending the post-translational model system to plastids, in addition to general proteome characterization, and the identification of functional homologues characterized in other organisms. We identified 454 loci that potentially encode TA proteins in Arabidopsis, and combined published data with new localization experiments to assign localizations to 130 proteins, including 29 associated with plastids. By analysing the tail anchor sequences of characterized proteins, we have developed a tool for predicting localization and estimate that 138 TA proteins are localized to plastids.
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Affiliation(s)
- Verena Kriechbaumer
- Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield, UK
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Guirimand G, Burlat V, Oudin A, Lanoue A, St-Pierre B, Courdavault V. Optimization of the transient transformation of Catharanthus roseus cells by particle bombardment and its application to the subcellular localization of hydroxymethylbutenyl 4-diphosphate synthase and geraniol 10-hydroxylase. PLANT CELL REPORTS 2009; 28:1215-34. [PMID: 19504099 DOI: 10.1007/s00299-009-0722-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 04/30/2009] [Accepted: 05/14/2009] [Indexed: 05/07/2023]
Abstract
The monoterpene indole alkaloids (MIA) synthesized in Catharanthus roseus are highly valuable metabolites due to their pharmacological properties. In planta, the MIA biosynthetic pathway exhibits a complex compartmentation at the cellular level, whereas subcellular data are sparse. To gain insight into this level of organization, we have developed a high efficiency green fluorescent protein (GFP) imaging approach to systematically localize MIA biosynthetic enzymes within C. roseus cells following a biolistic-mediated transient transformation. The biolistic transformation protocol has been first optimized to obtain a high number of transiently transformed cells with a ~12-fold increase compared to previous protocols and thus to clearly and easily identify the fusion GFP expression patterns in numerous cells. On the basis of this protocol, the subcellular localization of hydroxymethylbutenyl 4-diphosphate synthase (HDS), a methyl erythritol phosphate pathway enzyme and geraniol 10-hydroxylase (G10H), a monoterpene-secoiridoid pathway enzyme has been next characterized. Besides showing the accumulation of HDS within plastids of C. roseus cells, we also provide evidences of the presence of HDS in long stroma-filled thylakoid-free extensions budding from plastids, i.e. stromules that are in close association with other organelles such as endoplasmic reticulum (ER) or mitochondria in agreement with their proposed function in enhancing interorganelle metabolite exchanges. Furthermore, we also demonstrated that G10H is an ER-anchored protein, consistent with the presence of a transmembrane helix at the G10H N-terminal end, which is both necessary and sufficient to drive the ER anchoring.
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Affiliation(s)
- Grégory Guirimand
- Université François Rabelais de Tours, EA 2106 Biomolécules et Biotechnologies Végétales, IFR 135 Imagerie fonctionnelle, 37200, Tours, France
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Fan RC, Peng CC, Xu YH, Wang XF, Li Y, Shang Y, Du SY, Zhao R, Zhang XY, Zhang LY, Zhang DP. Apple sucrose transporter SUT1 and sorbitol transporter SOT6 interact with cytochrome b5 to regulate their affinity for substrate sugars. PLANT PHYSIOLOGY 2009; 150:1880-901. [PMID: 19502355 PMCID: PMC2719124 DOI: 10.1104/pp.109.141374] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 06/03/2009] [Indexed: 05/18/2023]
Abstract
Sugar transporters are central machineries to mediate cross-membrane transport of sugars into the cells, and sugar availability may serve as a signal to regulate the sugar transporters. However, the mechanisms of sugar transport regulation by signal sugar availability remain unclear in plant and animal cells. Here, we report that a sucrose transporter, MdSUT1, and a sorbitol transporter, MdSOT6, both localized to plasma membrane, were identified from apple (Malus domestica) fruit. Using a combination of the split-ubiquitin yeast two-hybrid, immunocoprecipitation, and bimolecular fluorescence complementation assays, the two distinct sugar transporters were shown to interact physically with an apple endoplasmic reticulum-anchored cytochrome b5 MdCYB5 in vitro and in vivo. In the yeast systems, the two different interaction complexes function to up-regulate the affinity of the sugar transporters, allowing cells to adapt to sugar starvation. An Arabidopsis (Arabidopsis thaliana) homolog of MdCYB5, AtCYB5-A, also interacts with the two sugar transporters and functions similarly. The point mutations leucine-73 --> proline in MdSUT1 and leucine-117 --> proline in MdSOT6, disrupting the bimolecular interactions but without significantly affecting the transporter activities, abolish the stimulating effects of the sugar transporter-cytochrome b5 complex on the affinity of the sugar transporters. However, the yeast (Saccharomyces cerevisiae) cytochrome b5 ScCYB5, an additional interacting partner of the two plant sugar transporters, has no function in the regulation of the sugar transporters, indicating that the observed biological functions in the yeast systems are specific to plant cytochrome b5s. These findings suggest a novel mechanism by which the plant cells tailor sugar uptake to the surrounding sugar availability.
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Affiliation(s)
- Ren-Chun Fan
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, China
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Sharma AK, Sharma MK. Plants as bioreactors: Recent developments and emerging opportunities. Biotechnol Adv 2009; 27:811-832. [PMID: 19576278 PMCID: PMC7125752 DOI: 10.1016/j.biotechadv.2009.06.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 06/15/2009] [Accepted: 06/16/2009] [Indexed: 12/18/2022]
Abstract
In recent years, the use of plants as bioreactors has emerged as an exciting area of research and significant advances have created new opportunities. The driving forces behind the rapid growth of plant bioreactors include low production cost, product safety and easy scale up. As the yield and concentration of a product is crucial for commercial viability, several strategies have been developed to boost up protein expression in transgenic plants. Augmenting tissue-specific transcription, elevating transcript stability, tissue-specific targeting, translation optimization and sub-cellular accumulation are some of the strategies employed. Various kinds of products that are currently being produced in plants include vaccine antigens, medical diagnostics proteins, industrial and pharmaceutical proteins, nutritional supplements like minerals, vitamins, carbohydrates and biopolymers. A large number of plant-derived recombinant proteins have reached advanced clinical trials. A few of these products have already been introduced in the market.
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Affiliation(s)
- Arun K Sharma
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India.
| | - Manoj K Sharma
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India
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Byers JT, Guzzo RM, Salih M, Tuana BS. Hydrophobic profiles of the tail anchors in SLMAP dictate subcellular targeting. BMC Cell Biol 2009; 10:48. [PMID: 19538755 PMCID: PMC2712456 DOI: 10.1186/1471-2121-10-48] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 06/19/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tail anchored (TA) membrane proteins target subcellular structures via a C-terminal transmembrane domain and serve prominent roles in membrane fusion and vesicle transport. Sarcolemmal Membrane Associated Protein (SLMAP) possesses two alternatively spliced tail anchors (TA1 or TA2) but their specificity of subcellular targeting remains unknown. RESULTS TA1 or TA2 can direct SLMAP to reticular structures including the endoplasmic reticulum (ER), whilst TA2 directs SLMAP additionally to the mitochondria. Despite the general structural similarity of SLMAP to other vesicle trafficking proteins, we found no evidence for its localization with the vesicle transport machinery or a role in vesicle transport. The predicted transmembrane region of TA2 is flanked on either side by a positively charged amino acid and is itself less hydrophobic than the transmembrane helix present in TA1. Substitution of the positively charged amino acids, in the regions flanking the transmembrane helix of TA2, with leucine did not alter its subcellular targeting. The targeting of SLMAP to the mitochondria was dependent on the hydrophobic nature of TA2 since targeting of SLMAP-TA2 was prevented by the substitution of leucine (L) for moderately hydrophobic amino acid residues within the transmembrane region. The SLMAP-TA2-4L mutant had a hydrophobic profile that was comparable to that of SLMAP-TA1 and had identical targeting properties to SLMAP-TA1. CONCLUSION Thus the overall hydrophobicity of the two alternatively spliced TAs in SLMAP determines its subcellular targeting and TA2 predominantly directs SLMAP to the mitochondira where it may serve roles in the function of this organelle.
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Affiliation(s)
- Joseph T Byers
- Department of Cellular and Molecular Medicine, 451 Smyth Road, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Rosa M Guzzo
- Department of Cellular and Molecular Medicine, 451 Smyth Road, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Maysoon Salih
- Department of Cellular and Molecular Medicine, 451 Smyth Road, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Balwant S Tuana
- Department of Cellular and Molecular Medicine, 451 Smyth Road, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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Nagano M, Ihara-Ohori Y, Imai H, Inada N, Fujimoto M, Tsutsumi N, Uchimiya H, Kawai-Yamada M. Functional association of cell death suppressor, Arabidopsis Bax inhibitor-1, with fatty acid 2-hydroxylation through cytochrome b₅. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 58:122-134. [PMID: 19054355 DOI: 10.1111/j.1365-313x.2008.03765.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Bax inhibitor-1 (BI-1) is a widely conserved cytoprotective protein localized in the endoplasmic reticulum (ER) membrane. We identified Arabidopsis cytochrome b(5) (AtCb5) as an interactor of Arabidopsis BI-1 (AtBI-1) by screening the Arabidopsis cDNA library with the split-ubiquitin yeast two-hybrid (suY2H) system. Cb5 is an electron transfer protein localized mainly in the ER membrane. In addition, a bimolecular fluorescence complementation (BiFC) assay and fluorescence resonance energy transfer (FRET) analysis confirmed that AtBI-1 interacted with AtCb5 in plants. On the other hand, we found that the AtBI-1-mediated suppression of cell death in yeast requires Saccharomyces cerevisiae fatty acid hydroxylase 1 (ScFAH1), which had a Cb5-like domain at the N terminus and interacted with AtBI-1. ScFAH1 is a sphingolipid fatty acid 2-hydroxylase localized in the ER membrane. In contrast, AtFAH1 and AtFAH2, which are functional ScFAH1 homologues in Arabidopsis, had no Cb5-like domain, and instead interacted with AtCb5 in plants. These results suggest that AtBI-1 interacts with AtFAHs via AtCb5 in plant cells. Furthermore, the overexpression of AtBI-1 increased the level of 2-hydroxy fatty acids in Arabidopsis, indicating that AtBI-1 is involved in fatty acid 2-hydroxylation.
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Affiliation(s)
- Minoru Nagano
- Institute of Molecular and Cellular Biosciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
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42
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Hwang YT, McCartney AW, Gidda SK, Mullen RT. Localization of the Carnation Italian ringspot virus replication protein p36 to the mitochondrial outer membrane is mediated by an internal targeting signal and the TOM complex. BMC Cell Biol 2008; 9:54. [PMID: 18811953 PMCID: PMC2573885 DOI: 10.1186/1471-2121-9-54] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Accepted: 09/23/2008] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Carnation Italian ringspot virus (CIRV) is a positive-strand RNA virus that causes massive structural alterations of mitochondria in infected host cells, the most conspicuous being the formation of numerous internal vesicles/spherules that are derived from the mitochondrial outer membrane and serve as the sites for viral RNA replication. While the membrane-bound components of the CIRV replication complex, including a 36-kD RNA-binding protein (p36), are known to be essential for these changes in mitochondrial morphology and are relatively well characterized in terms of their roles in nascent viral RNA synthesis, how these proteins are specifically targeted and inserted into mitochondria is poorly defined. RESULTS Here we report on the molecular signal responsible for sorting p36 to the mitochondrial outer membrane. Using a combination of gain-of-function assays with portions of p36 fused to reporter proteins and domain-swapping assays with p36 and another closely-related viral RNA-binding protein, p33, that sorts specifically to the peroxisomal boundary membrane, we show that the mitochondrial targeting information in p36 resides within its two transmembrane domains (TMDs) and intervening hydrophilic loop sequence. Comprehensive mutational analysis of these regions in p36 revealed that the primary targeting determinants are the moderate hydrophobicity of both TMDs and the positively-charged face of an amphipathic helix within the intervening loop sequence. We show also using bimolecular fluorescence complementation (BiFC) that p36 interacts with certain components of the translocase complex in the mitochondrial outer membrane (TOM), but not with the sorting and assembly machinery (SAM). CONCLUSION Our results provide insight to how viruses, such as CIRV, exploit specific host-cell protein sorting pathways to facilitate their replication. The characterization of the targeting and insertion of p36 into the mitochondrial outer membrane also sheds light on the mechanisms involved in sorting of host-cell membrane proteins to mitochondria, a process that has been largely unexplored in plants.
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Affiliation(s)
- Yeen Ting Hwang
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Andrew W McCartney
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
- JD Irving, Limited, Woodlands Division, 1350 Regent Street, Fredericton, New Brunswick, E3C 2G6, Canada
| | - Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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43
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Barbante A, Irons S, Hawes C, Frigerio L, Vitale A, Pedrazzini E. Anchorage to the cytosolic face of the endoplasmic reticulum membrane: a new strategy to stabilize a cytosolic recombinant antigen in plants. PLANT BIOTECHNOLOGY JOURNAL 2008; 6:560-75. [PMID: 18444969 DOI: 10.1111/j.1467-7652.2008.00342.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The levels of accumulation of recombinant vaccines in transgenic plants are protein specific and strongly influenced by the subcellular compartment of destination. The human immunodeficiency virus protein Nef (negative factor), a promising target for the development of an antiviral vaccine, is a cytosolic protein that accumulates to low levels in transgenic tobacco and is even more unstable when introduced into the secretory pathway, probably because of folding defects in the non-cytosolic environment. To improve Nef accumulation, a new strategy was developed to anchor the molecule to the cytosolic face of the endoplasmic reticulum (ER) membrane. For this purpose, the Nef sequence was fused to the C-terminal domain of mammalian ER cytochrome b5, a long-lived, tail-anchored (TA) protein. This consistently increased Nef accumulation by more than threefold in many independent transgenic tobacco plants. Real-time polymerase chain reaction of mRNA levels and protein pulse-chase analysis indicated that the increase was not caused by higher transcript levels but by enhanced protein stability. Subcellular fractionation and immunocytochemistry indicated that Nef-TA accumulated on the ER membrane. Over-expression of mammalian or plant ER cytochrome b5 caused the formation of stacked membrane structures, as observed previously in similar experiments performed in mammalian cells; however, Nef-TA did not alter membrane organization in tobacco cells. Finally, Nef could be removed in vitro by its tail-anchor, taking advantage of an engineered thrombin cleavage site. These results open up the way to use tail-anchors to improve foreign protein stability in the plant cytosol without perturbing cellular functions.
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MESH Headings
- Agrobacterium tumefaciens/genetics
- Amino Acid Sequence
- Animals
- Antigens, Viral/chemistry
- Antigens, Viral/genetics
- Antigens, Viral/metabolism
- Blotting, Western
- Cytochromes b5/chemistry
- Cytochromes b5/genetics
- Cytochromes b5/metabolism
- Cytosol/metabolism
- Cytosol/ultrastructure
- Endoplasmic Reticulum/metabolism
- Endoplasmic Reticulum/ultrastructure
- Fluorescent Antibody Technique
- Gene Products, nef/chemistry
- Gene Products, nef/genetics
- Gene Products, nef/metabolism
- Humans
- Microscopy, Confocal
- Microscopy, Electron, Transmission
- Molecular Sequence Data
- Plant Leaves/genetics
- Plant Leaves/metabolism
- Plant Leaves/ultrastructure
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/metabolism
- Plants, Genetically Modified/ultrastructure
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Nicotiana/genetics
- Nicotiana/metabolism
- Nicotiana/ultrastructure
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Affiliation(s)
- Alessandra Barbante
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, Via Bassini 15, 20133 Milan, Italy
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Dürr UH, Waskell L, Ramamoorthy A. The cytochromes P450 and b5 and their reductases—Promising targets for structural studies by advanced solid-state NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:3235-59. [DOI: 10.1016/j.bbamem.2007.08.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/08/2007] [Indexed: 02/02/2023]
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Borgese N, Brambillasca S, Colombo S. How tails guide tail-anchored proteins to their destinations. Curr Opin Cell Biol 2007; 19:368-75. [PMID: 17629691 DOI: 10.1016/j.ceb.2007.04.019] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 04/18/2007] [Indexed: 11/28/2022]
Abstract
A large group of diverse, functionally important, and differently localized transmembrane proteins shares a particular membrane topology, consisting of a cytosolic N-terminal region, followed by a transmembrane domain close to the C-terminus. Because of their structure, these C-tail-anchored (TA) proteins must insert into all their target membranes by post-translational pathways. Recent work, based on the development of stringent and sensitive biochemical assays, has demonstrated that novel unexplored mechanisms underlie these post-translational targeting and membrane insertion pathways. Unravelling these pathways will shed light on the biosynthesis and regulation of an important group of membrane proteins and is likely to lead to new concepts in the field of membrane biogenesis.
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Affiliation(s)
- Nica Borgese
- National Research Council Institute for Neuroscience and Department of Medical Pharmacology, University of Milan, via Vanvitelli 32, 20129 Milano, Italy
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