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Whitfield H, Rodriguez RF, Shipton ML, Li AW, Riley AM, Potter BV, Hemmings AM, Brearley CA. Crystal Structure and Enzymology of Solanum tuberosum Inositol Tris/Tetrakisphosphate Kinase 1 ( StITPK1). Biochemistry 2024; 63:42-52. [PMID: 38146842 PMCID: PMC10765375 DOI: 10.1021/acs.biochem.3c00404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 12/27/2023]
Abstract
Inositol phosphates and their pyrophosphorylated derivatives are responsive to the phosphate supply and are agents of phosphate homeostasis and other aspects of physiology. It seems likely that the enzymes that interconvert these signals work against the prevailing milieu of mixed populations of competing substrates and products. The synthesis of inositol pyrophosphates is mediated in plants by two classes of ATP-grasp fold kinase: PPIP5 kinases, known as VIH, and members of the inositol tris/tetrakisphosphate kinase (ITPK) family, specifically ITPK1/2. A molecular explanation of the contribution of ITPK1/2 to inositol pyrophosphate synthesis and turnover in plants is incomplete: the absence of nucleotide in published crystal structures limits the explanation of phosphotransfer reactions, and little is known of the affinity of potential substrates and competitors for ITPK1. Herein, we describe a complex of ADP and StITPK1 at 2.26 Å resolution and use a simple fluorescence polarization approach to compare the affinity of binding of diverse inositol phosphates, inositol pyrophosphates, and analogues. By simple HPLC, we reveal the novel catalytic capability of ITPK1 for different inositol pyrophosphates and show Ins(3,4,5,6)P4 to be a potent inhibitor of the inositol pyrophosphate-synthesizing activity of ITPK1. We further describe the exquisite specificity of ITPK1 for the myo-isomer among naturally occurring inositol hexakisphosphates.
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Affiliation(s)
- Hayley
L. Whitfield
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | - Raquel Faba Rodriguez
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | - Megan L. Shipton
- Medicinal
Chemistry & Drug Discovery, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, U.K.
| | - Arthur W.H. Li
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | - Andrew M. Riley
- Medicinal
Chemistry & Drug Discovery, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, U.K.
| | - Barry V.L. Potter
- Medicinal
Chemistry & Drug Discovery, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, U.K.
| | - Andrew M. Hemmings
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
- College
of Food Science and Technology, Shanghai
Ocean University, Shanghai 201306, China
| | - Charles A. Brearley
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
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2
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Sahu A, Verma R, Gupta U, Kashyap S, Sanyal I. An Overview of Targeted Genome Editing Strategies for Reducing the Biosynthesis of Phytic Acid: an Anti-nutrient in Crop Plants. Mol Biotechnol 2024; 66:11-25. [PMID: 37061991 DOI: 10.1007/s12033-023-00722-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 03/11/2023] [Indexed: 04/17/2023]
Abstract
Anti-nutrients are substances either found naturally or are of synthetic origin, which leads to the inactivation of nutrients and limits their utilization in metabolic processes. Phytic acid is classified as an anti-nutrient, as it has a strong binding affinity with most minerals like Fe, Zn, Mg, Ca, Mn, and Cd and impairs their proper metabolism. Removing anti-nutrients from cereal grains may enable the bioavailability of both macro- and micronutrients which is the desired goal of genetic engineering tools for the betterment of agronomic traits. Several strategies have been adopted to minimize phytic acid content in plants. Pursuing the molecular strategies, there are several studies, which result in the decrement of the total phytic acid content in grains of major as well as minor crops. Biosynthesis of phytic acid mainly takes place in the seed comprising lipid-dependent and lipid-independent pathways, involving various enzymes. Furthermore, some studies show that interruption of these enzymes may involve the pleiotropic effect. However, using modern biotechnological approaches, undesirable agronomic traits can be removed. This review presents an overview of different genes encoding the various enzymes involved in the biosynthetic pathway of phytic acid which is being targeted for its reduction. It also, highlights and enumerates the variety of potential applications of genome editing tools such as TALEN, ZFN, and CRISPR/Cas9 to knock out the desired genes, and RNAi for their silencing.
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Affiliation(s)
- Anshu Sahu
- Plant Transgenic Laboratory, Molecular Biology and Biotechnology Division, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, U.P, 226001, India
| | - Rita Verma
- Plant Transgenic Laboratory, Molecular Biology and Biotechnology Division, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, U.P, 226001, India
| | - Uma Gupta
- Plant Transgenic Laboratory, Molecular Biology and Biotechnology Division, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, U.P, 226001, India
| | - Shashi Kashyap
- Plant Transgenic Laboratory, Molecular Biology and Biotechnology Division, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, U.P, 226001, India
| | - Indraneel Sanyal
- Plant Transgenic Laboratory, Molecular Biology and Biotechnology Division, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, U.P, 226001, India.
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Vashishth A, Tehri N, Tehri P, Sharma A, Sharma AK, Kumar V. Unraveling the potential of bacterial phytases for sustainable management of phosphorous. Biotechnol Appl Biochem 2023; 70:1690-1706. [PMID: 37042496 DOI: 10.1002/bab.2466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 03/31/2023] [Indexed: 04/13/2023]
Abstract
Phosphorous actively participates in numerous metabolic and regulatory activities of almost all living organisms including animals and humans. Therefore, it is considered as an essential macronutrient required supporting their proper growth. On contrary, phytic acid (PA), an antinutritional substance, is widely known for its strong affinity to chelate essential mineral ions including PO4 3- , Ca2+ , Fe2+ , Mg2+ , and Zn2+ . Being one the major reservoir of PO4 3- ions, PA has great potential to bind PO4 3- ions in diverse range of foods. Once combined with P, PA transforms into an undigested and insoluble complex namely phytate. Produced phytate leads to a notable reduction in the bioavailability of P due to negligible activity of phytases in monogastric animals and humans. This highlights the importance and consequent need of enhancement of phytase level in these life forms. Interestingly, phytases, catalyzing the breakdown of phytate complex and recycling the phosphate into ecosystem to its available form, have naturally been reported in a variety of plants and microorganisms over past few decades. In pursuit of a reliable solution, the focus of this review is to explore the keynote potential of bacterial phytases for sustainable management of phosphorous via efficient utilization of soil phytate. The core of the review covers detailed discussion on bacterial phytases along with their widely reported applications viz. biofertilizers, phosphorus acquisition, and plant growth promotion. Moreover, meticulous description on fermentation-based strategies and future trends on bacterial phytases have also been included.
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Affiliation(s)
- Amit Vashishth
- Department of Science and Humanities, SRM Institute of Science & Technology, Ghaziabad, Uttar Pradesh, India
| | - Nimisha Tehri
- Centre for Biotechnology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Piyush Tehri
- Department of Applied Sciences, MIET, Meerut, Uttar Pradesh, India
| | - Avinash Sharma
- Faculty of Agricultural Sciences, Arunachal University of Studies, Namsai, Arunachal Pradesh, India
| | - Anil Kumar Sharma
- Department of Biotechnology, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, India
| | - Vineet Kumar
- Department of Microbiology, School of Life Sciences, Central University of Rajasthan, Kishangarh, Ajmer, Rajasthan, India
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Phillippy BQ, Donahue JL, Williams SP, Cridland CA, Perera IY, Gillaspy GE. Regulation of inositol 1,2,4,5,6-pentakisphosphate and inositol hexakisphosphate levels in Gossypium hirsutum by IPK1. PLANTA 2023; 257:46. [PMID: 36695941 DOI: 10.1007/s00425-023-04080-9] [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: 12/30/2022] [Accepted: 01/18/2023] [Indexed: 06/17/2023]
Abstract
The IPK1 genes, which code for 2-kinases that can synthesize Ins(1,2,4,5,6)P5 from Ins(1,4,5,6)P4, are expressed throughout cotton plants, resulting in the highest Ins(1,2,4,5,6)P5 concentrations in young leaves and flower buds. Cotton leaves contain large amounts of Ins(1,2,4,5,6)P5 and InsP6 compared to plants not in the Malvaceae family. The inositol polyphosphate pathway has been linked to stress tolerance in numerous plant species. Accordingly, we sought to determine why cotton and other Malvaceae have such high levels of these inositol phosphates. We have quantified the levels of InsP5 and InsP6 in different tissues of cotton plants and determined the expression of IPK1 (inositol 1,3,4,5,6-pentakisphosphate 2-kinase gene) in vegetative and reproductive tissues. Gossypium hirsutum was found to contain four IPK1 genes that were grouped into two pair (AB, CD) where each pair consists of very similar sequences that were measured together. More IPK1AB is expressed in leaves than in roots, whereas more IPK1CD is expressed in roots than in leaves. Leaves and flower buds have more InsP5 and InsP6 than stems and roots. Leaves and roots contain more InsP5 than InsP6, whereas flower buds and stems contain more InsP6 than InsP5. Dark-grown seedlings contain more InsP5 and InsP6 than those grown under lights, and the ratio of InsP5 to InsP6 is greater in the light-grown seedlings. During 35 days of the life cycle of the third true leaf, InsP5 and InsP6 gradually decreased by more than 50%. Silencing IPK1AB and IPK1CD with Cotton Leaf Crumple Virus-induced gene silencing (VIGS) resulted in plants with an intense viral phenotype, reduced IPK1AB expression and lowered amounts of InsP5. The results are consistent with Ins(1,2,4,5,6)P5 synthesis from Ins(1,4,5,6)P4 by IPK1. This study detailed the central role of IPK1 in cotton inositol polyphosphate metabolism, which has potential to be harnessed to improve the resistance of plants to different kinds of stress.
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Affiliation(s)
- Brian Q Phillippy
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA.
| | - Janet L Donahue
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA
| | - Sarah P Williams
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA
- Department of Biology, College of William and Mary, Williamsburg, VA, USA
| | | | - Imara Y Perera
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA
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Title: The Diversity of Phytic acid content and grain processing play decisive role on minerals bioavailability in rice. J Food Compost Anal 2022. [DOI: 10.1016/j.jfca.2022.105032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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6
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Zong G, Shears SB, Wang H. Structural and catalytic analyses of the InsP 6 kinase activities of higher plant ITPKs. FASEB J 2022; 36:e22380. [PMID: 35635723 PMCID: PMC9202514 DOI: 10.1096/fj.202200393r] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/04/2022] [Accepted: 05/16/2022] [Indexed: 09/21/2023]
Abstract
Inositol phosphate signaling in plants is of substantial agricultural interest, with a considerable focus on the inositol tris/tetrakisphosphate kinase (ITPK) family of inositol phosphate kinases. Historically, the 4-6 isoforms of ITPKs that higher plants each express have been studied for their multiplexing a metabolic pathway to synthesize inositol hexakisphosphate (ie InsP6 or phytate), through the phosphorylation and dephosphorylation of multiple inositol phosphates, including Ins(1,3,4,5,6)P5 (inositol-1,3,4,5,6-pentakisphosphate). A more recent discovery is ITPK-catalyzed phosphorylation of InsP6 to inositol pyrophosphates, which regulate plant immunity and phosphate homeostasis. However, a molecular-based explanation for these alternate catalytic activities has been missing, because no plant ITPK structure has previously been solved. Herein, we provide biochemical and structural analyses of ITPKs from Zea mays and Glycine max. For this work we introduce a simple, enzyme-coupled microplate-based assay of InsP6 kinase activity that should promote more general access to this important field. Furthermore, a ZmITPK1/InsP6 crystal complex is described at a resolution of 2.6 Å, which identifies a number of catalytically important residues; their functionality is confirmed by mutagenesis. We further demonstrate that ZmITPK1 adds a β-phosphate to the 3-position of Ins(1,2,3,4,5)P5 , yielding a candidate signal for regulating phosphate homeostasis. An impactful discovery is our description of a 29-residue catalytic specificity element; by interchanging this element between GmITPK1 and GmITPK2, we demonstrate how its isoform-specific sequence specifically determines whether the host protein phosphorylates InsP6 , without substantially affecting Ins(1,3,4,5,6)P5 metabolism. Our structural rationalization of key catalytic differences between alternate ITPK isoforms will complement future research into their functional diversity.
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Affiliation(s)
- Guangning Zong
- Inositol Signaling Section, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 USA
| | - Stephen B. Shears
- Inositol Signaling Section, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 USA
| | - Huanchen Wang
- Inositol Signaling Section, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 USA
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Riemer E, Pullagurla NJ, Yadav R, Rana P, Jessen HJ, Kamleitner M, Schaaf G, Laha D. Regulation of plant biotic interactions and abiotic stress responses by inositol polyphosphates. FRONTIERS IN PLANT SCIENCE 2022; 13:944515. [PMID: 36035672 PMCID: PMC9403785 DOI: 10.3389/fpls.2022.944515] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 07/20/2022] [Indexed: 05/14/2023]
Abstract
Inositol pyrophosphates (PP-InsPs), derivatives of inositol hexakisphosphate (phytic acid, InsP6) or lower inositol polyphosphates, are energy-rich signaling molecules that have critical regulatory functions in eukaryotes. In plants, the biosynthesis and the cellular targets of these messengers are not fully understood. This is because, in part, plants do not possess canonical InsP6 kinases and are able to synthesize PP-InsP isomers that appear to be absent in yeast or mammalian cells. This review will shed light on recent discoveries in the biosynthesis of these enigmatic messengers and on how they regulate important physiological processes in response to abiotic and biotic stresses in plants.
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Affiliation(s)
- Esther Riemer
- Departmentof Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
- *Correspondence: Esther Riemer,
| | | | - Ranjana Yadav
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Priyanshi Rana
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Henning J. Jessen
- Department of Chemistry and Pharmacy & CIBSS – The Center of Biological Signaling Studies, Albert-Ludwigs University Freiburg, Freiburg, Germany
| | - Marília Kamleitner
- Departmentof Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Gabriel Schaaf
- Departmentof Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Debabrata Laha
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
- Debabrata Laha,
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Laha D, Portela-Torres P, Desfougères Y, Saiardi A. Inositol phosphate kinases in the eukaryote landscape. Adv Biol Regul 2020; 79:100782. [PMID: 33422459 PMCID: PMC8024741 DOI: 10.1016/j.jbior.2020.100782] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/15/2020] [Accepted: 12/21/2020] [Indexed: 01/01/2023]
Abstract
Inositol phosphate encompasses a large multifaceted family of signalling molecules that originate from the combinatorial attachment of phosphate groups to the inositol ring. To date, four distinct inositol kinases have been identified, namely, IPK, ITPK, IPPK (IP5-2K), and PPIP5K. Although, ITPKs have recently been identified in archaea, eukaryotes have taken advantage of these enzymes to create a sophisticated signalling network based on inositol phosphates. However, it remains largely elusive what fundamental biochemical principles control the signalling cascade. Here, we present an evolutionary approach to understand the development of the 'inositol phosphate code' in eukaryotes. Distribution analyses of these four inositol kinase groups throughout the eukaryotic landscape reveal the loss of either ITPK, or of PPIP5K proteins in several species. Surprisingly, the loss of IPPK, an enzyme thought to catalyse the rate limiting step of IP6 (phytic acid) synthesis, was also recorded. Furthermore, this study highlights a noteworthy difference between animal (metazoan) and plant (archaeplastida) lineages. While metazoan appears to have a substantial amplification of IPK enzymes, archaeplastida genomes show a considerable increase in ITPK members. Differential evolution of IPK and ITPK between plant and animal lineage is likely reflective of converging functional adaptation of these two types of inositol kinases. Since, the IPK family comprises three sub-types IPMK, IP6K, and IP3-3K each with dedicated enzymatic specificity in metazoan, we propose that the amplified ITPK group in plant could be classified in sub-types with distinct enzymology.
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Affiliation(s)
- Debabrata Laha
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Paloma Portela-Torres
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Yann Desfougères
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK.
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Liu S, Hu ZM, Zhang Q, Yang X, Critchley AT, Duan D. PI signal transduction and ubiquitination respond to dehydration stress in the red seaweed Gloiopeltis furcata under successive tidal cycles. BMC PLANT BIOLOGY 2019; 19:516. [PMID: 31771523 PMCID: PMC6880600 DOI: 10.1186/s12870-019-2125-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 11/08/2019] [Indexed: 05/13/2023]
Abstract
BACKGROUND Intermittent dehydration caused by tidal changes is one of the most important abiotic factors that intertidal seaweeds must cope with in order to retain normal growth and reproduction. However, the underlying molecular mechanisms for the adaptation of red seaweeds to repeated dehydration-rehydration cycles remain poorly understood. RESULTS We chose the red seaweed Gloiopeltis furcata as a model and simulated natural tidal changes with two consecutive dehydration-rehydration cycles occurring over 24 h in order to gain insight into key molecular pathways and regulation of genes which are associated with dehydration tolerance. Transcription sequencing assembled 32,681 uni-genes (GC content = 55.32%), of which 12,813 were annotated. Weighted gene co-expression network analysis (WGCNA) divided all transcripts into 20 modules, with Coral2 identified as the key module anchoring dehydration-induced genes. Pathways enriched analysis indicated that the ubiquitin-mediated proteolysis pathway (UPP) and phosphatidylinositol (PI) signaling system were crucial for a successful response in G. furcata. Network-establishing and quantitative reverse transcription PCR (qRT-PCR) suggested that genes encoding ubiquitin-protein ligase E3 (E3-1), SUMO-activating enzyme sub-unit 2 (SAE2), calmodulin (CaM) and inositol-1,3,4-trisphosphate 5/6-kinase (ITPK) were the hub genes which responded positively to two successive dehydration treatments. Network-based interactions with hub genes indicated that transcription factor (e.g. TFIID), RNA modification (e.g. DEAH) and osmotic adjustment (e.g. MIP, ABC1, Bam1) were related to these two pathways. CONCLUSIONS RNA sequencing-based evidence from G. furcata enriched the informational database for intertidal red seaweeds which face periodic dehydration stress during the low tide period. This provided insights into an increased understanding of how ubiquitin-mediated proteolysis and the phosphatidylinositol signaling system help seaweeds responding to dehydration-rehydration cycles.
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Affiliation(s)
- Shun Liu
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071 People’s Republic of China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071 People’s Republic of China
- University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China
| | - Zi-Min Hu
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071 People’s Republic of China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071 People’s Republic of China
| | - Quansheng Zhang
- Ocean School, Yantai University, Yantai, 264005 People’s Republic of China
| | - Xiaoqi Yang
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071 People’s Republic of China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071 People’s Republic of China
- University of Chinese Academy of Sciences, Beijing, 100049 People’s Republic of China
| | - Alan T. Critchley
- Verschuren Centre for Sustainability in Energy and Environment, University of Cape Breton, Sydney, Nova Scotia Canada
| | - Delin Duan
- Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071 People’s Republic of China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071 People’s Republic of China
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Qamar ZU, Hameed A, Ashraf M, Rizwan M, Akhtar M. Development and Molecular Characterization of Low Phytate Basmati Rice Through Induced Mutagenesis, Hybridization, Backcross, and Marker Assisted Breeding. FRONTIERS IN PLANT SCIENCE 2019; 10:1525. [PMID: 31850026 PMCID: PMC6901921 DOI: 10.3389/fpls.2019.01525] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 11/01/2019] [Indexed: 06/10/2023]
Abstract
Breeding low phytate crops is the most viable solution to tackle mineral deficiencies. The objective of the present study was to develop high yielding, low phytate (lpa) basmati rice cultivars. Three homozygous lpa mutants, Lpa5, Lpa9, and Lpa59, were developed through induced mutations (gamma rays 60Co) and identified by colorimetric and High Performance Liquid Chromatography (HPLC) analysis. These mutants showed 54%-63% reduction in phytic acid but had poor germination and yield. To improve these traits, hybridization and back cross breeding involving Lpa5, Lpa59, and parent cultivar Super Basmati were performed and F2:3, F3:4, BC1F2:3, and BC1F3:4 generations were developed and screened to target the objective. Within the F2:3, homozygous (226), heterozygous (65), and wild type (46) lpa recombinants were identified. Within the homozygous lpa category, four recombinants (Lpa5, Lpa6, Lpa7, and Lpa30) showed improved germination. Within the F3:4 generation, 86 homozygous lpa recombinants were identified. Further selection, on the basis of better plant type and the low phytate trait resulted in the selection of 38 recombinants. Grain quality and cooking characteristics of these selected recombinants were comparable as compared to parent cultivar. Within the BC1F2:3 generations, two homozygous Lpa recombinant lines, Lpa141, and Lpa205, were selected out of 220. Screening of the BC1F3:4 generation for the desirable agronomic and low phytate trait also resulted in the selection of two homozygous lines. Finally, seven recombinants i.e. Lpa12-3, Lpa111-1, Lpa141, Lpa56-3, Lpa53-4, Lpa99-2, and Lpa205-4 out of 42 homozygous low phytate lines were selected on the basis of yield improvement (4%-18%) as compared to parent cultivar. Association analysis suggested that further selection based on primary branches per plant, panicle length and productive tillers per plant would further improve the paddy yield. For molecular characterization of the Lpa trait, previously reported Lpa1-CAPS and Lpa1-InDel and functional molecular markers were applied. Results indicated the absence of the Z9B-Lpa allele and XS-Lpa mutation in the OsMRP5 gene in tested mutants, possibly suggesting that there may be new mutations or novel alleles in tested mutants that need to be identified and then fine mapped for subsequent utilization. To our knowledge, this is the first report of low phytic acid rice mutant development and their improved germination and yield through backcross breeding in basmati rice.
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Affiliation(s)
- Zia-ul- Qamar
- Plant Breeding and Genetics Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan
| | - Amjad Hameed
- Plant Breeding and Genetics Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan
| | - Muhammad Ashraf
- Plant Breeding and Genetics Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan
| | - Muhammad Rizwan
- Plant Breeding and Genetics Division, Nuclear Institute of Agriculture (NIA), Tando Jam (Sindh), Pakistan
| | - Muhammad Akhtar
- Soil and Environmental Sciences Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan
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Díaz-Sáez L, Torrie LS, McElroy SP, Gray D, Hunter WN. Burkholderia pseudomallei d-alanine-d-alanine ligase; detailed characterisation and assessment of a potential antibiotic drug target. FEBS J 2019; 286:4509-4524. [PMID: 31260169 PMCID: PMC6899670 DOI: 10.1111/febs.14976] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/27/2019] [Accepted: 06/27/2019] [Indexed: 02/02/2023]
Abstract
Burkholderia pseudomallei is a serious, difficult to treat Gram‐negative pathogen and an increase in the occurrence of drug‐resistant strains has been detected. We have directed efforts to identify and to evaluate potential drug targets relevant to treatment of infection by B. pseudomallei. We have selected and characterised the essential enzyme d‐alanine‐d‐alanine ligase (BpDdl), required for the ATP‐assisted biosynthesis of a peptidoglycan precursor. A recombinant supply of protein supported high‐resolution crystallographic and biophysical studies with ligands (AMP and AMP+d‐Ala‐d‐Ala), and comparisons with orthologues enzymes suggest a ligand‐induced conformational change occurring that might be relevant to the catalytic cycle. The detailed biochemical characterisation of the enzyme, development and optimisation of ligand binding assays supported the search for novel inhibitors by screening of selected compound libraries. In a similar manner to that observed previously in other studies, we note a paucity of hits that are worth follow‐up and then in combination with a computational analysis of the active site, we conclude that this ligase represents a difficult target for drug discovery. Nevertheless, our reagents, protocols and data can underpin future efforts exploiting more diverse chemical libraries and structure‐based approaches.
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Affiliation(s)
- Laura Díaz-Sáez
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, UK
| | - Leah S Torrie
- Drug Discovery Unit, Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, UK
| | - Stuart P McElroy
- European Screening Centre Newhouse, Biocity Scotland, University of Dundee, Newhouse, UK
| | - David Gray
- Drug Discovery Unit, Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, UK
| | - William N Hunter
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, UK
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12
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Punjabi M, Bharadvaja N, Sachdev A, Krishnan V. Molecular characterization, modeling, and docking analysis of late phytic acid biosynthesis pathway gene, inositol polyphosphate 6-/ 3-/ 5-kinase, a potential candidate for developing low phytate crops. 3 Biotech 2018; 8:344. [PMID: 30073129 PMCID: PMC6064606 DOI: 10.1007/s13205-018-1343-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 07/06/2018] [Indexed: 01/08/2023] Open
Abstract
The coding sequence of inositol polyphosphate 6-/3-/5-kinase (GmIPK2) gene was identified and cloned from popular Indian soybean cultivar Pusa-16. The clone was predicted to encode 279 amino acids long, 30.97 kDa protein. Multiple sequence alignment revealed an inositol phosphate-binding motif, PxxxDxKxG throughout the IPK2 sequences along with other motifs unique to inositol phosphate kinase superfamily. Eight α-helices and eight β-strands in antiparallel β-sheets arrangement were predicted in the secondary structure of GmIPK2. The temporal analysis of GmIPK2 revealed maximum expression in the seed tissues during later stages of development while spatially the transcript levels were lowest in leaf and stem tissues. Endosperm-specific cis-regulatory motifs (GCN4 and Skn_1) which support high levels of expression, as observed in the developing seeds, were detected in its promoter region. The protein structure of GmIPK2 was modeled based on the crystal structure of inositol polyphosphate multikinase from Arabidopsis thaliana (PDB:4FRF) and subsequently docked with inositol phosphate ligands (PDB: 5GUG-I3P and PDB: 4A69-I0P). Molecular dynamics (MD) simulation established the structural stability of both, modeled enzyme and ligand-bound complexes. Docking in combination with trajectory analysis for 50 ns MD run confirmed the participation of Lys105, Lys126 and Arg153 residues in the formation of a network of hydrogen bonds to stabilize the ligand-receptor interaction. Results of the present study thus provide valuable information on structural and functional aspects of GmIPK2 which shall assist in strategizing our long-term goal of achieving phytic acid reduction in soybean by genetic modification of its biosynthetic pathway to develop a nutritionally enhanced crop in the future.
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Affiliation(s)
- Mansi Punjabi
- Department of Biotechnology, Delhi Technological University (Formerly Delhi College of Engineering), New Delhi, 110042 India
- Division of Biochemistry, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Navneeta Bharadvaja
- Department of Biotechnology, Delhi Technological University (Formerly Delhi College of Engineering), New Delhi, 110042 India
| | - Archana Sachdev
- Division of Biochemistry, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Veda Krishnan
- Division of Biochemistry, Indian Agricultural Research Institute, New Delhi, 110012 India
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Sparvoli F, Cominelli E. Seed Biofortification and Phytic Acid Reduction: A Conflict of Interest for the Plant? PLANTS 2015; 4:728-55. [PMID: 27135349 PMCID: PMC4844270 DOI: 10.3390/plants4040728] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/13/2015] [Indexed: 02/03/2023]
Abstract
Most of the phosphorus in seeds is accumulated in the form of phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate, InsP6). This molecule is a strong chelator of cations important for nutrition, such as iron, zinc, magnesium, and calcium. For this reason, InsP6 is considered an antinutritional factor. In recent years, efforts to biofortify seeds through the generation of low phytic acid (lpa) mutants have been noteworthy. Moreover, genes involved in the biosynthesis and accumulation of this molecule have been isolated and characterized in different species. Beyond its role in phosphorus storage, phytic acid is a very important signaling molecule involved in different regulatory processes during plant development and responses to different stimuli. Consequently, many lpa mutants show different negative pleitotropic effects. The strength of these pleiotropic effects depends on the specific mutated gene, possible functional redundancy, the nature of the mutation, and the spatio-temporal expression of the gene. Breeding programs or transgenic approaches aimed at development of new lpa mutants must take into consideration these different aspects in order to maximize the utility of these mutants.
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Affiliation(s)
- Francesca Sparvoli
- Institute of Agricultural Biology and Biotechnology, CNR, Via Bassini 15, 20133 Milan, Italy.
| | - Eleonora Cominelli
- Institute of Agricultural Biology and Biotechnology, CNR, Via Bassini 15, 20133 Milan, Italy.
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14
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Aggarwal S, Shukla V, Bhati KK, Kaur M, Sharma S, Singh A, Mantri S, Pandey AK. Hormonal Regulation and Expression Profiles of Wheat Genes Involved during Phytic Acid Biosynthesis Pathway. PLANTS 2015; 4:298-319. [PMID: 27135330 PMCID: PMC4844322 DOI: 10.3390/plants4020298] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 05/26/2015] [Accepted: 06/01/2015] [Indexed: 11/16/2022]
Abstract
Phytic acid (PA) biosynthesis pathway genes were reported from multiple crop species. PA accumulation was enhanced during grain filling and at that time, hormones like Abscisic acid (ABA) and Gibberellic acid (GA3) interplay to control the process of seed development. Regulation of wheat PA pathway genes has not yet been reported in seeds. In an attempt to find the clues for the regulation by hormones, the promoter region of wheat PA pathway genes was analyzed for the presence of cis-elements. Multiple cis-elements of those known to be involved for ABA, GA3, salicylic acid (SA), and cAMP sensing were identified in the promoters of PA pathway genes. Eight genes (TaIMP, TaITPK1-4, TaPLC1, TaIPK2 and TaIPK1) involved in the wheat PA biosynthesis pathway were selected for the expression studies. The temporal expression response was studied in seeds treated with ABA and GA3 using quantitative real time PCR. Our results suggested that exogenous application of ABA induces few PA pathway genes in wheat grains. Comparison of expression profiles for PA pathway for GA3 and ABA suggested the antagonistic regulation of certain genes. Additionally, to reveal stress responses of wheat PA pathway genes, expression was also studied in the presence of SA and cAMP. Results suggested SA specific differential expression of few genes, whereas, overall repression of genes was observed in cAMP treated samples. This study is an effort to understand the regulation of PA biosynthesis genes in wheat.
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Affiliation(s)
- Sipla Aggarwal
- Department of Biotechnology, National Agri-Food Biotechnology Institute, C-127 Industrial Area, S.A.S-Nagar, Phase-8, Mohali, Punjab 160071, India.
| | - Vishnu Shukla
- Department of Biotechnology, National Agri-Food Biotechnology Institute, C-127 Industrial Area, S.A.S-Nagar, Phase-8, Mohali, Punjab 160071, India.
| | - Kaushal Kumar Bhati
- Department of Biotechnology, National Agri-Food Biotechnology Institute, C-127 Industrial Area, S.A.S-Nagar, Phase-8, Mohali, Punjab 160071, India.
| | - Mandeep Kaur
- Department of Biotechnology, National Agri-Food Biotechnology Institute, C-127 Industrial Area, S.A.S-Nagar, Phase-8, Mohali, Punjab 160071, India.
| | - Shivani Sharma
- Department of Biotechnology, National Agri-Food Biotechnology Institute, C-127 Industrial Area, S.A.S-Nagar, Phase-8, Mohali, Punjab 160071, India.
| | - Anuradha Singh
- Department of Biotechnology, National Agri-Food Biotechnology Institute, C-127 Industrial Area, S.A.S-Nagar, Phase-8, Mohali, Punjab 160071, India.
| | - Shrikant Mantri
- Department of Biotechnology, National Agri-Food Biotechnology Institute, C-127 Industrial Area, S.A.S-Nagar, Phase-8, Mohali, Punjab 160071, India.
| | - Ajay Kumar Pandey
- Department of Biotechnology, National Agri-Food Biotechnology Institute, C-127 Industrial Area, S.A.S-Nagar, Phase-8, Mohali, Punjab 160071, India.
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15
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Bhati KK, Aggarwal S, Sharma S, Mantri S, Singh SP, Bhalla S, Kaur J, Tiwari S, Roy JK, Tuli R, Pandey AK. Differential expression of structural genes for the late phase of phytic acid biosynthesis in developing seeds of wheat (Triticum aestivum L.). PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 224:74-85. [PMID: 24908508 DOI: 10.1016/j.plantsci.2014.04.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 03/28/2014] [Accepted: 04/11/2014] [Indexed: 05/04/2023]
Abstract
In cereals, phytic acid (PA) or inositol hexakisphosphate (IP6) is a well-known phosphate storage compound as well as major chelator of important micronutrients (iron, zinc, calcium, etc.). Genes involved in the late phases of PA biosynthesis pathway are known in crops like maize, soybeans and barley but none have been reported from wheat. Our in silico analysis identified six wheat genes that might be involved in the biosynthesis of inositol phosphates. Four of the genes were inositol tetraphosphate kinases (TaITPK1, TaITPK2, TaITPK3, and TaITPK4), and the other two genes encode for inositol triphosphate kinase (TaIPK2) and inositol pentakisphosphate kinase (TaIPK1). Additionally, we identified a homolog of Zmlpa-1, an ABCC subclass multidrug resistance-associated transporter protein (TaMRP3) that is putatively involved in PA transport. Analyses of the mRNA expression levels of these seven genes showed that they are differentially expressed during seed development, and that some are preferentially expressed in aleurone tissue. These results suggest selective roles during PA biosynthesis, and that both lipid-independent and -dependent pathways are active in developing wheat grains. TaIPK1 and TaMRP3 were able to complement the yeast ScΔipk1 and ScΔycf1 mutants, respectively, providing evidence that the wheat genes have the expected biochemical functions. This is the first comprehensive study of the wheat genes involved in the late phase of PA biosynthesis. Knowledge generated from these studies could be utilized to develop strategies for generating low phyate wheat.
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Affiliation(s)
- Kaushal Kumar Bhati
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Sipla Aggarwal
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Shivani Sharma
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Shrikant Mantri
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Sudhir P Singh
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Sherry Bhalla
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Jagdeep Kaur
- Department of Biotechnology, Panjab University, Punjab, India
| | - Siddharth Tiwari
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Joy K Roy
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Rakesh Tuli
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India
| | - Ajay K Pandey
- National Agri-Food Biotechnology Institute, Department of Biotechnology, Government of India, C-127, Industrial Area, S.A.S. Nagar, Phase 8, Mohali 160071, Punjab, India.
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16
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Li WX, Zhao HJ, Pang WQ, Cui HR, Poirier Y, Shu QY. Seed-specific silencing of OsMRP5 reduces seed phytic acid and weight in rice. Transgenic Res 2014; 23:585-99. [PMID: 24648215 DOI: 10.1007/s11248-014-9792-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Accepted: 03/10/2014] [Indexed: 11/29/2022]
Abstract
Phytic acid (PA) is poorly digested by humans and monogastric animals and negatively affects human/animal nutrition and the environment. Rice mutants with reduced PA content have been developed but are often associated with reduced seed weight and viability, lacking breeding value. In the present study, a new approach was explored to reduce seed PA while attaining competitive yield. The OsMRP5 gene, of which mutations are known to reduce seed PA as well as seed yield and viability, was down-regulated specifically in rice seeds by using an artificial microRNA driven by the rice seed specific promoter Ole18. Seed PA contents were reduced by 35.8-71.9% in brown rice grains of transgenic plants compared to their respective null plants (non-transgenic plants derived from the same event). No consistent significant differences of plant height or number of tillers per plant were observed, but significantly lower seed weights (up to 17.8% reduction) were detected in all transgenic lines compared to null plants, accompanied by reductions of seed germination and seedling emergence. It was observed that the silencing of the OsMRP5 gene increased the inorganic P (Pi) levels (up to 7.5 times) in amounts more than the reduction of PA-P in brown rice. This indicates a reduction in P content in other cellular compounds, such as lipids and nucleic acids, which may affect overall seed development. Put together, the present study demonstrated that seed specific silencing of OsMRP5 could significantly reduce the PA content and increase Pi levels in seeds; however, it also significantly lowers seed weight in rice. Discussions were made regarding future directions towards producing agronomically competitive and nutritionally valuable low PA rice.
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Affiliation(s)
- Wen-Xu Li
- State Key Laboratory of Rice Biology and Key Laboratory of Nuclear-Agricultural Sciences of the Ministry of Agriculture and Zhejiang Province, Institute of Nuclear Agricultural Sciences, Zhejiang University, Hangzhou, 310029, China
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17
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Tang Y, Tan S, Xue H. Arabidopsis inositol 1,3,4-trisphosphate 5/6 kinase 2 is required for seed coat development. Acta Biochim Biophys Sin (Shanghai) 2013; 45:549-60. [PMID: 23595027 DOI: 10.1093/abbs/gmt039] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inositol 1,3,4-trisphosphate 5/6 kinase (ITPK) phosphorylates inositol 1,3,4-trisphosphate to form inositol 1,3,4,5-tetrakisphosphate and inositol 1,3,4,6-tetrakisphosphate which can be finally transferred to inositol hexaphosphate (IP₆) and play important roles during plant growth and development. There are 4 putative ITPK members in Arabidopsis. Expression pattern analysis showed that ITPK2 is constitutively expressed in various tissues. A T-DNA knockout mutant of ITPK2 was identified and scanning electron microscopy (SEM) analysis showed that the epidermis structure of seed coat was irregularly formed in seeds of itpk2-1 mutant, resulting in the increased permeability of seed coat to tetrazolium salts. Further analysis by gas chromatography coupled with mass spectrometry of lipid polyester monomers in cell wall confirmed a dramatic decrease in composition of suberin and cutin, which relate to the permeability of seed coat and the formation of which is accompanied with seed coat development. These results indicate that ITPK2 plays an essential role in seed coat development and lipid polyester barrier formation.
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Affiliation(s)
- Yong Tang
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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18
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Yuan FJ, Zhu DH, Tan YY, Dong DK, Fu XJ, Zhu SL, Li BQ, Shu QY. Identification and characterization of the soybean IPK1 ortholog of a low phytic acid mutant reveals an exon-excluding splice-site mutation. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2012; 125:1413-23. [PMID: 22733447 DOI: 10.1007/s00122-012-1922-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 06/11/2012] [Indexed: 05/07/2023]
Abstract
Phytic acid (myo-inositol 1, 2, 3, 4, 5, 6 hexakisphosphate) is an important constituent of soybean meal. Since phytic acid and its mineral salts (phytates) are almost indigestible for monogastrics, their abundance in grain food/feed causes nutritional and environmental problems; interest in breeding low phytic acid has therefore increased considerably. Based on gene mapping and the characteristics of inositol polyphosphates profile in the seeds of a soybean mutant line Gm-lpa-ZC-2, the soybean ortholog of inositol 1,3,4,5,6 pentakisphosphate (InsP(5)) 2-kinase (IPK1), which transforms InsP(5) into phytic acid, was first hypothesized as the candidate gene responsible for the low phytic acid alteration in Gm-lpa-ZC-2. One IPK1 ortholog (Glyma14g07880, GmIPK1) was then identified in the mapped region on chromosome 14. Sequencing revealed a G → A point mutation in the genomic DNA sequence and the exclusion of the entire fifth exon in the cDNA sequence of GmIPK1 in Gm-lpa-ZC-2 compared with its wild-type progenitor Zhechun No. 3. The excluded exon encodes 37 amino acids that spread across two conserved IPK1 motifs. Furthermore, complete co-segregation of low phytic acid phenotype with the G → A mutation was observed in the F(2) population of ZC-lpa x Zhexiandou No. 4 (a wild-type cultivar). Put together, the G → A point mutation affected the pre-mRNA splicing and resulted in the exclusion of the fifth exon of GmIPK1 which is expected to disrupt the GmIPK1 functionality, leading to low phytic acid level in Gm-lpa-ZC-2. Gm-lpa-ZC-2, would be a good germplasm source in low phytic acid soybean breeding.
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Affiliation(s)
- Feng-Jie Yuan
- Institute of Crop Science and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China
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19
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Synthesis of inositol phosphate ligands of plant hormone-receptor complexes: pathways of inositol hexakisphosphate turnover. Biochem J 2012; 444:601-9. [PMID: 22429240 DOI: 10.1042/bj20111811] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Reduction of phytate is a major goal of plant breeding programs to improve the nutritional quality of crops. Remarkably, except for the storage organs of crops such as barley, maize and soybean, we know little of the stereoisomeric composition of inositol phosphates in plant tissues. To investigate the metabolic origins of higher inositol phosphates in photosynthetic tissues, we have radiolabelled leaf tissue of Solanum tuberosum with myo-[2-3H]inositol, undertaken a detailed analysis of inositol phosphate stereoisomerism and permeabilized mesophyll protoplasts in media containing inositol phosphates. We describe the inositol phosphate composition of leaf tissue and identify pathways of inositol phosphate metabolism that we reveal to be common to other kingdoms. Our results identify the metabolic origins of a number of higher inositol phosphates including ones that are precursors of cofactors, or cofactors of plant hormone-receptor complexes. The present study affords alternative explanations of the effects of disruption of inositol phosphate metabolism reported in other species, and identifies different inositol phosphates from that described in photosynthetic tissue of the monocot Spirodela polyrhiza. We define the pathways of inositol hexakisphosphate turnover and shed light on the occurrence of a number of inositol phosphates identified in animals, for which metabolic origins have not been defined.
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20
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Baños-Sanz JI, Sanz-Aparicio J, Whitfield H, Hamilton C, Brearley CA, González B. Conformational changes in inositol 1,3,4,5,6-pentakisphosphate 2-kinase upon substrate binding: role of N-terminal lobe and enantiomeric substrate preference. J Biol Chem 2012; 287:29237-49. [PMID: 22745128 DOI: 10.1074/jbc.m112.363671] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IP(5) 2-K) catalyzes the synthesis of inositol 1,2,3,4,5,6-hexakisphosphate from ATP and IP(5). Inositol 1,2,3,4,5,6-hexakisphosphate is implicated in crucial processes such as mRNA export, DNA editing, and phosphorus storage in plants. We previously solved the first structure of an IP(5) 2-K, which shed light on aspects of substrate recognition. However, failure of IP(5) 2-K to crystallize in the absence of inositide prompted us to study putative conformational changes upon substrate binding. We have made mutations to residues on a region of the protein that produces a clasp over the active site. A W129A mutant allowed us to capture IP(5) 2-K in its different conformations by crystallography. Thus, the IP(5) 2-K apo-form structure displays an open conformation, whereas the nucleotide-bound form shows a half-closed conformation, in contrast to the inositide-bound form obtained previously in a closed conformation. Both nucleotide and inositide binding produce large conformational changes that can be understood as two rigid domain movements, although local changes were also observed. Changes in intrinsic fluorescence upon nucleotide and inositide binding are in agreement with the crystallographic findings. Our work suggests that the clasp might be involved in enzyme kinetics, with the N-terminal lobe being essential for inositide binding and subsequent conformational changes. We also show how IP(5) 2-K discriminates between inositol 1,3,4,5-tetrakisphosphate and 3,4,5,6-tetrakisphosphate enantiomers and that substrate preference can be manipulated by Arg(130) mutation. Altogether, these results provide a framework for rational design of specific inhibitors with potential applications as biological tools for in vivo studies, which could assist in the identification of novel roles for IP(5) 2-K in mammals.
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Affiliation(s)
- José Ignacio Baños-Sanz
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física Rocasolano, CSIC, Serrano 119, 28006-Madrid, Spain
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21
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Du H, Liu L, You L, Yang M, He Y, Li X, Xiong L. Characterization of an inositol 1,3,4-trisphosphate 5/6-kinase gene that is essential for drought and salt stress responses in rice. PLANT MOLECULAR BIOLOGY 2011; 77:547-63. [PMID: 22038091 DOI: 10.1007/s11103-011-9830-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 09/12/2011] [Indexed: 05/06/2023]
Abstract
Drought and salt stresses are major limiting factors for crop production. To identify critical genes for stress resistance in rice (Oryza sativa L.), we screened T-DNA mutants and identified a drought- and salt-hypersensitive mutant dsm3. The mutant phenotype was caused by a T-DNA insertion in a gene encoding a putative inositol 1,3,4-trisphosphate 5/6-kinase previously named OsITPK2 with unknown function. Under drought stress conditions, the mutant had significantly less accumulation of osmolytes such as proline and soluble sugar and showed significantly reduced root volume, spikelet fertility, biomass, and grain yield; however, malondialdehyde level was increased in the mutant. Interestingly, overexpression of DSM3 (OsITPK2) in rice resulted in drought- and salt-hypersensitive phenotypes and physiological changes similar to those in the mutant. Inositol trisphosphate (IP3) level was decreased in the overexpressors under normal condition and drought stress. A few genes related to osmotic adjustment and reactive oxygen species scavenging were down-regulated in the mutant and overexpression lines. The expression level of DSM3 promoter-driven β-glucuronidase (GUS) reporter gene in rice was induced by drought, salt and abscisic acid. Protoplast transient expression assay indicated that DSM3 is an endoplasmic reticulum protein. Sequence analysis revealed six putative ITPKs in rice. Transcript level analysis of OsITPK genes revealed that they had different tempo-spatial expression patterns, and the responses of DSM3 to abiotic stresses, including drought, salinity, cold, and high temperature, were distinct from the other five members in rice. These results together suggest that DSM3/OsITPK2 is an important member of the OsITPK family for stress responses, and an optimal expression level is essential for drought and salt tolerance in rice.
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Affiliation(s)
- Hao Du
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, 430070 Wuhan, China
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22
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Abstract
The simple polyol, myo-inositol, is used as a building block of a cellular language that plays various roles in signal transduction. This review describes the terminology used to denote myo-inositol-containing molecules, with an emphasis on how phosphate and fatty acids are added to create second messengers used in signaling. Work in model systems has delineated the genes and enzymes required for synthesis and metabolism of many myo-inositol-containing molecules, with genetic mutants and measurement of second messengers playing key roles in developing our understanding. There is increasing evidence that molecules such as myo- inositol(1,4,5)trisphosphate and phosphatidylinositol(4,5)bisphosphate are synthesized in response to various signals plants encounter. In particular, the controversial role of myo-inositol(1,4,5)trisphosphate is addressed, accompanied by a discussion of the multiple enzymes that act to regulate this molecule. We are also beginning to understand new connections of myo-inositol signaling in plants. These recent discoveries include the novel roles of inositol phosphates in binding to plant hormone receptors and that of phosphatidylinositol(3)phosphate binding to pathogen effectors.
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Affiliation(s)
- Glenda E Gillaspy
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
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23
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Identification of genes necessary for wild-type levels of seed phytic acid in Arabidopsis thaliana using a reverse genetics approach. Mol Genet Genomics 2011. [PMID: 21698461 DOI: 10.1007/s00438‐011‐0631‐2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2022]
Abstract
The majority of phosphorus (P) in seeds is found in phytic acid (InsP(6)) which accumulates as the mixed salt phytate. InsP(6) is generally considered to be an anti-nutrient and the development of low phytic acid (lpa) seed crops is of significant interest. We have employed a reverse genetics approach to examine the impact of disrupting genes involved in inositol phosphate metabolism on Arabidopsis seed InsP(6) levels. Our analysis revealed that knockout mutations in three genes (AtITPK1, AtITPK4, and AtMIK/At5g58730) reduced seed InsP(6) in addition to knockouts of four previously reported genes (AtIPK1, AtIPK2β, AtMRP5, and At5g60760). Seeds of these lpa mutants also exhibited reduced germination under various stress conditions. The greatest reduction in InsP(6) (>70%) was observed in atmrp5 seeds which were also among the least sensitive to the stresses examined. Expression analysis of the lpa genes revealed three distinct patterns in developing siliques consistent with their presumed roles. Disruption of each lpa gene resulted in changes in the expression in some of the other lpa genes indicating that transcription of lpa genes is modulated by other constituents of InsP(6) metabolism. While all the lpa genes represent possible targets for genetic engineering of low phytate seed crops, mutations in AtMRP5, AtMIK, and At5g60760 may be most successful for conventional approaches such as mutation breeding.
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Kim SI, Tai TH. Identification of genes necessary for wild-type levels of seed phytic acid in Arabidopsis thaliana using a reverse genetics approach. Mol Genet Genomics 2011; 286:119-33. [PMID: 21698461 DOI: 10.1007/s00438-011-0631-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 05/27/2011] [Indexed: 11/26/2022]
Abstract
The majority of phosphorus (P) in seeds is found in phytic acid (InsP(6)) which accumulates as the mixed salt phytate. InsP(6) is generally considered to be an anti-nutrient and the development of low phytic acid (lpa) seed crops is of significant interest. We have employed a reverse genetics approach to examine the impact of disrupting genes involved in inositol phosphate metabolism on Arabidopsis seed InsP(6) levels. Our analysis revealed that knockout mutations in three genes (AtITPK1, AtITPK4, and AtMIK/At5g58730) reduced seed InsP(6) in addition to knockouts of four previously reported genes (AtIPK1, AtIPK2β, AtMRP5, and At5g60760). Seeds of these lpa mutants also exhibited reduced germination under various stress conditions. The greatest reduction in InsP(6) (>70%) was observed in atmrp5 seeds which were also among the least sensitive to the stresses examined. Expression analysis of the lpa genes revealed three distinct patterns in developing siliques consistent with their presumed roles. Disruption of each lpa gene resulted in changes in the expression in some of the other lpa genes indicating that transcription of lpa genes is modulated by other constituents of InsP(6) metabolism. While all the lpa genes represent possible targets for genetic engineering of low phytate seed crops, mutations in AtMRP5, AtMIK, and At5g60760 may be most successful for conventional approaches such as mutation breeding.
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Affiliation(s)
- Sang-Ic Kim
- Crops Pathology and Genetics Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Department of Plant Sciences - MS 1, University of California, Davis, CA 95616, USA
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Fassetti F, Leone O, Palopoli L, Rombo SE, Saiardi A. IP6K gene identification in plant genomes by tag searching. BMC Proc 2011; 5 Suppl 2:S1. [PMID: 21554757 PMCID: PMC3090757 DOI: 10.1186/1753-6561-5-s2-s1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Plants have played a special role in inositol polyphosphate (IP) research since in plant seeds was discovered the first IP, the fully phosphorylated inositol ring of phytic acid (IP6). It is now known that phytic acid is further metabolized by the IP6 Kinases (IP6Ks) to generate IP containing pyro-phosphate moiety. The IP6K are evolutionary conserved enzymes identified in several mammalian, fungi and amoebae species. Although IP6K has not yet been identified in plant chromosomes, there are many clues suggesting its presences in vegetal cells. Results In this paper we propose a new approach to search for the plant IP6K gene, that lead to the identification in plant genome of a nucleotide sequence corresponding to a specific tag of the IP6K family. Such a tag has been found in all IP6K genes identified up to now, as well as in all genes belonging to the Inositol Polyphosphate Kinases superfamily (IPK). The tag sequence corresponds to the inositol-binding site of the enzyme, and it can be considered as characterizing all IPK genes. To this aim we applied a technique based on motif discovery. We exploited DLSME, a software recently proposed, which allows for the motif structure to be only partially specified by the user. First we applied the new method on mitochondrial DNA (mtDNA) of plants, where such a gene could have been nested, possibly encrypted and hidden by virtue of the editing and/or trans-splicing processes. Then we looked for the gene in nuclear genome of two model plants, Arabidopsis thaliana and Oryza sativa. Conclusions The analysis we conducted in plant mitochondria provided the negative, though we argue relevant, result that IP6K does not actually occur in vegetable mtDNA. Very interestingly, the tag search in nuclear genomes lead us to identify a promising sequence in chromosome 5 of Oryza sativa. Further analyses are in course to confirm that this sequence actually corresponds to IP6K mammalian gene.
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Affiliation(s)
- Fabio Fassetti
- DEIS, Università della Calabria, Via Pietro Bucci 41C Rende (CS) Italy.
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Kim SI, Tai TH. Genetic analysis of two OsLpa1-like genes in Arabidopsis reveals that only one is required for wild-type seed phytic acid levels. PLANTA 2010; 232:1241-1250. [PMID: 20734061 DOI: 10.1007/s00425-010-1243-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Accepted: 07/28/2010] [Indexed: 05/29/2023]
Abstract
Phytic acid (inositol-1,2,3,4,5,6-hexakisphosphate or InsP(6)) is the primary storage form of phosphorus in plant seeds. The rice OsLpa1 encodes a novel protein required for wild-type levels of seed InsP(6) and was identified from a low phytic acid (lpa) mutant exhibiting a 45-50% reduction in seed InsP(6). OsLpa1 is highly conserved in plants and Arabidopsis contains two OsLpa1-like genes, At3g45090 and At5g60760. Analysis of homozygous T-DNA insertion mutants of At5g60760 revealed significantly reduced levels of seed InsP(6) while no changes were observed in seeds of At3g45090 mutants. A double knockout mutant of At5g60760 and At3g45090 was created and its seed InsP(6) content was similar to that of the At5g60760 mutant indicating that At3g45090 does not provide functional redundancy. OsLpa1 was confirmed to be the ortholog of At5g60760 by complementation of a knockout mutant with a cDNA clone corresponding to the largest of three alternative transcripts of OsLpa1. The spatial and temporal expression of At5g60760 during seed development is consistent with its involvement in seed InsP(6) biosynthesis.
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Affiliation(s)
- Sang-Ic Kim
- US Department of Agriculture, Agricultural Research Service, Department of Plant Sciences, University of California, Davis, CA 95616, USA
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Mutations in genes controlling the biosynthesis and accumulation of inositol phosphates in seeds. Biochem Soc Trans 2010; 38:689-94. [PMID: 20298244 DOI: 10.1042/bst0380689] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Most of the phosphorus in the resting seed is stored inside protein storage vacuoles as PA (phytic acid; InsP(6)). The biosynthesis and accumulation of PA can be detected beginning from a few days after anthesis and seem to continue during seed development until maturation. The first step in PA biosynthesis is the formation of Ins3P by conversion of glucose 6-phosphate. This is then followed by a sequential and ordered phosphorylation of the remaining five positions of the inositol ring by a number of kinases, resulting in PA. Identification of low-PA mutants in cereals, legumes and Arabidopsis is instrumental for resolving the biosynthetic pathway and identification of genes controlling the accumulation of PA. Mutations in seven genes involved in the metabolism of PA have been identified and characterized among five plant species using induced mutagenesis and insertion elements. Understanding the biosynthetic pathway and genes controlling the accumulation of PA in plant seeds and how PA may balance the free phosphate is of importance for molecular breeding of crop plants, particularly cereals and legumes.
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Xu XH, Zhao HJ, Liu QL, Frank T, Engel KH, An G, Shu QY. Mutations of the multi-drug resistance-associated protein ABC transporter gene 5 result in reduction of phytic acid in rice seeds. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2009; 119:75-83. [PMID: 19370321 DOI: 10.1007/s00122-009-1018-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 03/20/2009] [Indexed: 05/24/2023]
Abstract
Phytic acid (PA, myo-inositol 1,2,3,4,5,6-hexakisphosphate) is important to the nutritional quality of cereal and legume seeds. PA and its salts with micronutrient cations, such as iron and zinc, cannot be digested by humans and non-ruminant animals, and hence may affect food/feed nutritional value and cause P pollution of groundwater from animal waste. We previously developed a set of low phytic acid (LPA) rice mutant lines with the aim of increasing the nutritional quality of rice. Two of these lines, Os-lpa-XS110-2 (homozygous non-lethal) Os-lpa-XS110-3 (homozygous lethal), contain two mutant alleles of a LPA gene (hereafter XS-lpa2-1 and XS-lpa2-2, respectively). In this study, we mapped the XS-lpa2-1 gene to a region on chromosome 3 between microsatellite markers RM14360 and RM1332, where the rice orthologue (OsMRP5) of the maize lpa1 gene is located. Sequence analysis of the OsMRP5 gene revealed a single base pair change (C/G-T/A transition) in the sixth exon of XS-lpa2-1 and a 5-bp deletion in the first exon of XS-lpa2-2. OsMRP5 is expressed in both vegetative tissues and developing seeds, and the two mutations do not change the level of RNA transcription. A T-DNA insertion line, 4A-02500, in which OsMRP5 was disrupted, also showed the same high inorganic phosphorus phenotype as Os-lpa-XS110-3 and appeared to be homozygous lethal. PA is significantly reduced in Os-lpa-XS110-2 (~20%) and in 4A-02500 (~90%) seeds compared with their wild type lines, and no PA was detected in Os-lpa-XS110-3 using HPLC analysis. This evidence indicates that the OsMRP5 gene plays an important role in PA metabolism in rice seeds.
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Affiliation(s)
- Xiu-Hong Xu
- IAEA-Zhejiang University Collaborating Center, and National Key Laboratory of Rice Biology, Institute of Nuclear Agricultural Sciences, Zhejiang University, Hangzhou, China
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Shears SB. Molecular basis for the integration of inositol phosphate signaling pathways via human ITPK1. ACTA ACUST UNITED AC 2009; 49:87-96. [PMID: 19200440 DOI: 10.1016/j.advenzreg.2008.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Stephen B Shears
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHSS, Research Triangle Park, NC 27709, USA.
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Kim SI, Andaya CB, Newman JW, Goyal SS, Tai TH. Isolation and characterization of a low phytic acid rice mutant reveals a mutation in the rice orthologue of maize MIK. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2008; 117:1291-301. [PMID: 18726583 DOI: 10.1007/s00122-008-0863-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Accepted: 07/31/2008] [Indexed: 05/10/2023]
Abstract
Using a forward genetics approach, we isolated two independent low phytic acid (lpa) rice mutants, N15-186 and N15-375. Both mutants are caused by single gene, recessive non-lethal mutations, which result in approximately 75% (N15-186) and 43% (N15-375) reductions in seed phytic acid (inositol hexakisphosphate). High-performance liquid chromatography and GC-MS analysis of seed extracts from N15-186 indicated that, in addition to phytic acid, inositol monophosphate was significantly reduced whereas inorganic phosphorus and myo-inositol were greatly increased when compared with wild-type. The changes observed in N15-186 resemble those previously described for the maize lpa3 mutant. Analysis of N15-375 revealed changes similar to those observed in previously characterized rice lpa1 mutants (i.e. significant reduction in phytic acid and corresponding increase in inorganic phosphorus with little or no change in inositol phosphate intermediates or myo-inositol). Further genetic analysis of the N15-186 mutant indicated that the mutation, designated lpa N15-186, was located in a region on chromosome 3 between the microsatellite markers RM15875 and RM15907. The rice orthologue of maize lpa3, which encodes a myo-inositol kinase, is in this interval. Sequence analysis of the N15-186 allele of this orthologue (Os03g52760) revealed a single base pair change (C/G to T/A) in the first exon of the gene, which results in a nonsense mutation. Our results indicate that lpa N15-186 is a mutant allele of the rice myo-inositol kinase (OsMIK) gene. Identification and characterization of lpa mutants, such as N15-186, will facilitate studies on the regulation of phytic acid biosynthesis and accumulation and help address questions concerning the contribution of the inositol lipid-dependent and independent biosynthetic pathways to the production of seed phytic acid.
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Affiliation(s)
- S I Kim
- USDA-ARS Crops Pathology and Genetics Research Unit, Department of Plant Sciences, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
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Stiles AR, Qian X, Shears SB, Grabau EA. Metabolic and signaling properties of an Itpk gene family in Glycine max. FEBS Lett 2008; 582:1853-8. [PMID: 18474240 PMCID: PMC2515385 DOI: 10.1016/j.febslet.2008.04.054] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 04/28/2008] [Accepted: 04/29/2008] [Indexed: 11/21/2022]
Abstract
We have cloned and characterized four Itpk genes from soybean. All four recombinant Itpk proteins showed canonical Ins(1,3,4)P3 5/6-kinase activity, but a kinetic analysis raised questions about its biological significance. Instead, we provide evidence that one alternative biological role for soybean Itpks is to interconvert the Cl(-) channel inhibitor, Ins(3,4,5,6)P4, and its metabolic precursor, Ins(1,3,4,5,6)P5, within a substrate cycle. The soybean Itpks also phosphorylated Ins(3,4,6)P3 to Ins(1,3,4,6)P4 which was further phosphorylated to Ins(1,3,4,5,6)P5 by soybean Ipk2. Thus, soybean Itpks may participate in an inositol lipid-independent pathway of InsP6 synthesis.
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Affiliation(s)
| | | | - Stephen B. Shears
- Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (A.R.S, E.A.G);, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHSS, Research Triangle Park, NC 27709 (X.Q., S.B.S.)
| | - Elizabeth A. Grabau
- Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (A.R.S, E.A.G);, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHSS, Research Triangle Park, NC 27709 (X.Q., S.B.S.)
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Bohn L, Meyer AS, Rasmussen SK. Phytate: impact on environment and human nutrition. A challenge for molecular breeding. J Zhejiang Univ Sci B 2008; 9:165-91. [PMID: 18357620 DOI: 10.1631/jzus.b0710640] [Citation(s) in RCA: 264] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Phytic acid (PA) is the primary storage compound of phosphorus in seeds accounting for up to 80% of the total seed phosphorus and contributing as much as 1.5% to the seed dry weight. The negatively charged phosphate in PA strongly binds to metallic cations of Ca, Fe, K, Mg, Mn and Zn making them insoluble and thus unavailable as nutritional factors. Phytate mainly accumulates in protein storage vacuoles as globoids, predominantly located in the aleurone layer (wheat, barley and rice) or in the embryo (maize). During germination, phytate is hydrolysed by endogenous phytase(s) and other phosphatases to release phosphate, inositol and micronutrients to support the emerging seedling. PA and its derivatives are also implicated in RNA export, DNA repair, signalling, endocytosis and cell vesicular trafficking. Our recent studies on purification of phytate globoids, their mineral composition and dephytinization by wheat phytase will be discussed. Biochemical data for purified and characterized phytases isolated from more than 23 plant species are presented, the dephosphorylation pathways of phytic acid by different classes of phytases are compared, and the application of phytase in food and feed is discussed.
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Affiliation(s)
- Lisbeth Bohn
- Department of Agricultural Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
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Caddick SEK, Harrison CJ, Stavridou I, Mitchell JL, Hemmings AM, Brearley CA. A Solanum tuberosum inositol phosphate kinase (StITPK1) displaying inositol phosphate-inositol phosphate and inositol phosphate-ADP phosphotransferase activities. FEBS Lett 2008; 582:1731-7. [PMID: 18442482 DOI: 10.1016/j.febslet.2008.04.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 04/10/2008] [Accepted: 04/10/2008] [Indexed: 10/22/2022]
Abstract
We describe a multifunctional inositol polyphosphate kinase/phosphotransferase from Solanum tuberosum, StITPKalpha (GenBank accession number: EF362784), hereafter called StITPK1. StITPK1 displays inositol 3,4,5,6-tetrakisphosphate 1-kinase activity: K(m) = 27 microM, and V(max) = 19 nmol min(-1) mg(-1). The enzyme displays inositol 1,3,4,5,6-pentakisphosphate 1-phosphatase activity in the absence of a nucleotide acceptor and inositol 1,3,4,5,6-pentakisphosphate-ADP phosphotransferase activity in the presence of physiological concentrations of ADP. Additionally, StITPK1 shows inositol phosphate-inositol phosphate phosphotransferase activity. Homology modelling provides a structural rationale of the catalytic abilities of StITPK1. Inter-substrate transfer of phosphate groups between inositol phosphates is an evolutionarily conserved function of enzymes of this class.
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Affiliation(s)
- Samuel E K Caddick
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
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Saiardi A, Cockcroft S. Human ITPK1: a reversible inositol phosphate kinase/phosphatase that links receptor-dependent phospholipase C to Ca2+-activated chloride channels. Sci Signal 2008; 1:pe5. [PMID: 18272466 DOI: 10.1126/stke.14pe5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Inositol 3,4,5,6-tetrakisphosphate [Ins(3,4,5,6)P4] is an inhibitor of the conductance of the Ca(2+)-activated chloride channels in the plasma membrane. These ion channels are required for salt and fluid secretion from epithelial cells, for cell volume homeostasis, and for electrical excitability in neurons and smooth muscle. The enzyme ITPK1 (inositol 1,3,4-triphosphate 5/6 kinase) is the source of Ins(3,4,5,6)P4. It can phosphorylate both Ins(1,3,4)P3 at the 5 or 6 positions and Ins(3,4,5,6)P4 at the 1 position and can also dephosphorylate Ins(1,3,4,5,6)P5 to Ins(3,4,5,6)P4. A study now shows that these various enzyme activities manifested by ITPK1 provide a molecular mechanism that allows the receptor-activated changes in phospholipase C activity and consequent increases in the concentration of Ins(1,3,4)P3 to regulate the abundance of Ins(3,4,5,6)P4. ITPK1 sequesters a tightly bound nucleotide that can accept a phosphate from, or donate a phosphate directly to, an inositol polyphosphate without the nucleotide being released in the bulk medium. This phenomenon of "intersubstrate" transfer is found only in the human enzyme, which can use Ins(1,3,4)P3 to promote increased cellular concentrations of Ins(3,4,5,6)P4.
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Affiliation(s)
- Adolfo Saiardi
- Medical Research Council Cell Biology Unit and Laboratory of Molecular Cell Biology, University College London, London, UK
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Frank T, Meuleye BS, Miller A, Shu QY, Engel KH. Metabolite profiling of two low phytic acid (lpa) rice mutants. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:11011-11019. [PMID: 18052121 DOI: 10.1021/jf0723559] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Two low phytic acid (lpa) rice mutant lines, Os-lpa-XS110-1 and Os-lpa-XS110-2, were grown together with their parent wild-type variety Xiushui 110 in four field trials. HPLC analysis of inositol phosphates in the seeds produced demonstrated that compared to the wild-type, the reduction in phytic acid content in Os-lpa-XS110-1 (-46%) was more pronounced than that in Os-lpa-XS110-2 (-23%). Lower inositol phosphates (InsP 3, InsP 4, InsP 5) were not detected in the mutants. The lpa mutants and the wild-type rice were subjected to comparative metabolite profiling by capillary gas chromatography. On average, 34% (Os-lpa-XS110-1) and 42% (Os-lpa-XS110-2) of the detected peaks were statistically significantly different between wild-type and mutants. However, only a few of these differences could be consistently observed for all field trials. Identification and quantification of the consistently different metabolites revealed that contents of myo-inositol and raffinose were increased in Os-lpa-XS110-1 but decreased in Os-lpa-XS110-2 compared to the wild-type. In addition, Os-lpa-XS110-1 exhibited increased levels of galactose and galactinol. Consideration of these metabolic changes in light of the routes involved in the biosynthesis of phytic acid indicated a disturbance in the early biosynthetic pathway of phytic acid in Os-lpa-XS110-2 (similar to the lpa-1 type mutation in maize) and a mutation event affecting phosphorylation of myo-inositol in Os-lpa-XS110-1 (similar to the lpa-3-type mutation).
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Affiliation(s)
- Thomas Frank
- Lehrstuhl für Allgemeine Lebensmitteltechnologie, Technische Universität München, Freising-Weihenstephan, Germany
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Bohn L, Josefsen L, Meyer AS, Rasmussen SK. Quantitative analysis of phytate globoids isolated from wheat bran and characterization of their sequential dephosphorylation by wheat phytase. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:7547-52. [PMID: 17696444 DOI: 10.1021/jf071191t] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Wheat phytase was purified to investigate the action of the enzyme toward its pure substrate (phytic acid - myo-inositol hexakisphosphate) and its naturally occurring substrate (phytate globoids). Phytate globoids were purified to homogeneity from wheat bran, and their nutritionally relevant parameters were quantified by ICP-MS. The main components of the globoids were phytic acid (40% w/w), protein (46% w/w), and several minerals, in particular, K > Mg > Ca > Fe (in concentration order). Investigation of enzyme kinetics revealed that K(m) and V(max) decreased by 29 and 37%, respectively, when pure phytic acid was replaced with phytate globoids as substrate. Time course degradation of phytic acid or phytate globoids using purified wheat phytase was followed by HPIC identification of inositol phosphates appearing and disappearing as products. In both cases, enzymatic degradation initiated at both the 3- and 6-positions of phytic acid and end products were inositol and phosphate.
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Affiliation(s)
- Lisbeth Bohn
- Department of Agricultural Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
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Sweetman D, Stavridou I, Johnson S, Green P, Caddick SEK, Brearley CA. Arabidopsis thaliana inositol 1,3,4-trisphosphate 5/6-kinase 4 (AtITPK4) is an outlier to a family of ATP-grasp fold proteins from Arabidopsis. FEBS Lett 2007; 581:4165-71. [PMID: 17698066 DOI: 10.1016/j.febslet.2007.07.046] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 07/16/2007] [Accepted: 07/19/2007] [Indexed: 10/23/2022]
Abstract
The Arabidopsis genome encodes a family of inositol 1,3,4-trisphosphate 5/6-kinases which form a subgroup of a larger group of ATP-grasp fold proteins. An analysis of the inositol 1,3,4-trisphosphate 5/6-kinase family might, ultimately, be best rewarded by detailed comparison of related enzymes in a single genome. The enzyme encoded by At2G43980, AtITPK4; is an outlier to its family. At2G43980 is expressed in male and female organs of young and mature flowers. AtITPK4 differs from other family members in that it does not display inositol 3,4,5,6-tetrakisphosphate 1-kinase activity; rather, it displays inositol 1,4,5,6-tetrakisphosphate and inositol 1,3,4,5-tetrakisphosphate isomerase activity.
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Affiliation(s)
- Dylan Sweetman
- School of Biological Sciences, University of East Anglia, Earlham Road, Norwich, Norfolk, UK
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