1
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Kamble NU, Makhamadjonov F, Fahy B, Martins C, Saalbach G, Seung D. Initiation of B-type starch granules in wheat endosperm requires the plastidial α-glucan phosphorylase PHS1. THE PLANT CELL 2023; 35:4091-4110. [PMID: 37595145 PMCID: PMC10615211 DOI: 10.1093/plcell/koad217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/24/2023] [Accepted: 07/28/2023] [Indexed: 08/20/2023]
Abstract
The plastidial α-glucan phosphorylase (PHS1) can elongate and degrade maltooligosaccharides (MOSs), but its exact physiological role in plants is poorly understood. Here, we discover a specialized role of PHS1 in establishing the unique bimodal characteristic of starch granules in wheat (Triticum spp.) endosperm. Wheat endosperm contains large A-type granules that initiate at early grain development and small B-type granules that initiate in later grain development. We demonstrate that PHS1 interacts with B-GRANULE CONTENT1 (BGC1), a carbohydrate-binding protein essential for normal B-type granule initiation. Mutants of tetraploid durum wheat (Triticum turgidum) deficient in all homoeologs of PHS1 had normal A-type granules but fewer and larger B-type granules. Grain size and starch content were not affected by the mutations. Further, by assessing granule numbers during grain development in the phs1 mutant and using a double mutant defective in both PHS1 and BGC1, we demonstrate that PHS1 is exclusively involved in B-type granule initiation. The total starch content and number of starch granules per chloroplast in leaves were not affected by loss of PHS1, suggesting that its role in granule initiation in wheat is limited to the endosperm. We therefore propose that the initiation of A- and B-type granules occurs via distinct biochemical mechanisms, where PHS1 plays an exclusive role in B-type granule initiation.
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Affiliation(s)
| | | | - Brendan Fahy
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH,UK
| | - Carlo Martins
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH,UK
| | | | - David Seung
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH,UK
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2
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Dong X, Chen L, Yang H, Tian L, Dong F, Chai Y, Qu LQ. Pho1 cooperates with DPE1 to control short maltooligosaccharide mobilization during starch synthesis initiation in rice endosperm. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2023; 136:47. [PMID: 36912930 DOI: 10.1007/s00122-023-04250-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 10/18/2022] [Indexed: 06/18/2023]
Abstract
Plastidial α-glucan phosphorylase is a key factor that cooperates with plastidial disproportionating enzyme to control short maltooligosaccharide mobilization during the initiation process of starch molecule synthesis in developing rice endosperm. Storage starch synthesis is essential for grain filling. However, little is known about how cereal endosperm controls starch synthesis initiation. One of core events for starch synthesis initiation is short maltooligosaccharide (MOS) mobilization consisting of long MOS primer production and excess MOS breakdown. By mutant analyses and biochemical investigations, we present here functional identifications of plastidial α-glucan phosphorylase (Pho1) and disproportionating enzyme (DPE1) during starch synthesis initiation in rice (Oryza sativa) endosperm. Pho1 deficiency impaired MOS mobilization, triggering short MOS accumulation and starch synthesis reduction during early seed development. The mutant seeds differed significantly in MOS level and starch content at 15 days after flowering and exhibited diverse endosperm phenotypes during mid-late seed development: ranging from pseudonormal to shrunken (Shr), severely or excessively Shr. The level of DPE1 was almost normal in the PN seeds but significantly reduced in the Shr seeds. Overexpression of DPE1 in pho1 resulted in plump seeds only. DPE1 deficiency had no obvious effects on MOS mobilization. Knockout of DPE1 in pho1 completely blocked MOS mobilization, resulting in severely and excessively Shr seeds only. These findings show that Pho1 cooperates with DPE1 to control short MOS mobilization during starch synthesis initiation in rice endosperm.
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Affiliation(s)
- Xiangbai Dong
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100093, China
| | - Liangke Chen
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Huifang Yang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lihong Tian
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100093, China
| | - Fengqin Dong
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100093, China
| | - Yaru Chai
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Le Qing Qu
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100093, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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3
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Watson-Lazowski A, Raven E, Feike D, Hill L, Barclay JE, Smith AM, Seung D. Loss of PROTEIN TARGETING TO STARCH 2 has variable effects on starch synthesis across organs and species. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:6367-6379. [PMID: 35716106 PMCID: PMC9578351 DOI: 10.1093/jxb/erac268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/15/2022] [Indexed: 05/12/2023]
Abstract
Recent work has identified several proteins involved in starch granule initiation, the first step of starch synthesis. However, the degree of conservation in the granule initiation process remains poorly understood, especially among grass species differing in patterns of carbohydrate turnover in leaves, and granule morphology in the endosperm. We therefore compared mutant phenotypes of Hordeum vulgare (barley), Triticum turgidum (durum wheat), and Brachypodium distachyon defective in PROTEIN TARGETING TO STARCH 2 (PTST2), a key granule initiation protein. We report striking differences across species and organs. Loss of PTST2 from leaves resulted in fewer, larger starch granules per chloroplast and normal starch content in wheat, fewer granules per chloroplast and lower starch content in barley, and almost complete loss of starch in Brachypodium. The loss of starch in Brachypodium leaves was accompanied by high levels of ADP-glucose and detrimental effects on growth and physiology. Additionally, we found that loss of PTST2 increased granule initiation in Brachypodium amyloplasts, resulting in abnormal compound granule formation throughout the seed. These findings suggest that the importance of PTST2 varies greatly with the genetic and developmental background and inform the extent to which the gene can be targeted to improve starch in crops.
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Affiliation(s)
| | - Emma Raven
- John Innes Centre, Norwich Research Park, Norwich, UK
| | - Doreen Feike
- John Innes Centre, Norwich Research Park, Norwich, UK
| | - Lionel Hill
- John Innes Centre, Norwich Research Park, Norwich, UK
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4
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Fang K, Deng L, Yin J, Yang T, Li J, He W. Recent advances in starch-based magnetic adsorbents for the removal of contaminants from wastewater: A review. Int J Biol Macromol 2022; 218:909-929. [PMID: 35914554 DOI: 10.1016/j.ijbiomac.2022.07.175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 07/03/2022] [Accepted: 07/22/2022] [Indexed: 02/09/2023]
Abstract
Considerable concern exists regarding water contamination by various pollutants, such as conventional pollutants (e.g., heavy metals and organics) and emerging micropollutants (e.g., consumer care products and interfering endocrine-related compounds). Currently, academics are continuously exploring sustainability-related materials and technologies to remove contaminants from wastewater. Magnetic starch-based adsorbents (MSAs) can combine the advantages of starch and magnetic nanoparticles, which exhibit unique critical features such as availability, cost-effectiveness, size, shape, crystallinity, magnetic properties, stability, adsorption properties, and excellent surface properties. However, limited reviews on MSAs' preparations, characterizations, applications, and adsorption mechanisms could be available nowadays. Hence, this review not only focuses on their activation and preparation methods, including physical (e.g., mechanical activation treatment, microwave radiation treatment, sonication, and extrusion), chemical (e.g., grafting, cross-linking, oxidation and esterification), and enzymatic modifications to enhance their adsorption properties, but also offers an all-round state-of-the-art analysis of the full range of its characterization methods, the adsorption of various contaminants, and the underlying adsorption mechanisms. Eventually, this review focuses on the recycling and reclamation performance and highlights the main gaps in the areas where further studies are warranted. We hope that this review will spark an interdisciplinary discussion and bring about a revolution in the applications of MSAs.
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Affiliation(s)
- Kun Fang
- School of Chemistry and Chemical Engineering, School of Resources, Environment and Materials, Guangxi Key Laboratory of Processing for Non-ferrous Metallic and Featured Materials Guangxi University, Nanning 530004, Guangxi, China; College of Light Industry and Food Engineering, the Collaborative Innovation Center for Guangxi Sugar Industry, Nanning 530004, Guangxi, China
| | - Ligao Deng
- College of Light Industry and Food Engineering, the Collaborative Innovation Center for Guangxi Sugar Industry, Nanning 530004, Guangxi, China
| | - Jiangyu Yin
- College of Light Industry and Food Engineering, the Collaborative Innovation Center for Guangxi Sugar Industry, Nanning 530004, Guangxi, China
| | - Tonghan Yang
- School of Chemistry and Chemical Engineering, School of Resources, Environment and Materials, Guangxi Key Laboratory of Processing for Non-ferrous Metallic and Featured Materials Guangxi University, Nanning 530004, Guangxi, China
| | - Jianbin Li
- College of Light Industry and Food Engineering, the Collaborative Innovation Center for Guangxi Sugar Industry, Nanning 530004, Guangxi, China.
| | - Wei He
- School of Chemistry and Chemical Engineering, School of Resources, Environment and Materials, Guangxi Key Laboratory of Processing for Non-ferrous Metallic and Featured Materials Guangxi University, Nanning 530004, Guangxi, China.
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5
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Muntaha SN, Li X, Compart J, Apriyanto A, Fettke J. Carbon pathways during transitory starch degradation in Arabidopsis differentially affect the starch granule number and morphology in the dpe2/phs1 mutant background. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 180:35-41. [PMID: 35378390 DOI: 10.1016/j.plaphy.2022.03.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 03/24/2022] [Accepted: 03/26/2022] [Indexed: 06/14/2023]
Abstract
The Arabidopsis knockout mutant lacking both the cytosolic disproportionating enzyme 2 (DPE2) and the plastidial phosphorylase (PHS1) had a dwarf-growth phenotype, a reduced and uneven distribution of starch within the plant rosettes, and a lower starch granule number per chloroplast under standard growth conditions. In contrast, a triple mutant impaired in starch degradation by its additional lack of the glucan, water dikinase (GWD) showed improved plant growth, a starch-excess phenotype, and a homogeneous starch distribution. Furthermore, the number of starch granules per chloroplast was increased and was similar to the wild type. We concluded that ongoing starch degradation is mainly responsible for the observed phenotype of dpe2/phs1. Next, we generated two further triple mutants lacking either the phosphoglucan, water dikinase (PWD), or the disproportionating enzyme 1 (DPE1) in the background of the double mutant. Analysis of the starch metabolism revealed that even minor ongoing starch degradation observed in dpe2/phs1/pwd maintained the double mutant phenotype. In contrast, an additional blockage in the glucose pathway of starch breakdown, as in dpe2/phs1/dpe1, resulted in a nearly starch-free phenotype and massive chloroplast degradation. The characterized mutants were discussed in the context of starch granule formation.
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Affiliation(s)
- Sidratul Nur Muntaha
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, Potsdam-Golm, Germany
| | - Xiaoping Li
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, Potsdam-Golm, Germany
| | - Julia Compart
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, Potsdam-Golm, Germany
| | - Ardha Apriyanto
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, Potsdam-Golm, Germany
| | - Joerg Fettke
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, Potsdam-Golm, Germany.
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6
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Apriyanto A, Compart J, Fettke J. A review of starch, a unique biopolymer - Structure, metabolism and in planta modifications. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 318:111223. [PMID: 35351303 DOI: 10.1016/j.plantsci.2022.111223] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/02/2022] [Accepted: 02/16/2022] [Indexed: 06/14/2023]
Abstract
Starch is a complex carbohydrate polymer produced by plants and especially by crops in huge amounts. It consists of amylose and amylopectin, which have α-1,4- and α-1,6-linked glucose units. Despite this simple chemistry, the entire starch metabolism is complex, containing various (iso)enzymes/proteins. However, whose interplay is still not yet fully understood. Starch is essential for humans and animals as a source of nutrition and energy. Nowadays, starch is also commonly used in non-food industrial sectors for a variety of purposes. However, native starches do not always satisfy the needs of a wide range of (industrial) applications. This review summarizes the structural properties of starch, analytical methods for starch characterization, and in planta starch modifications.
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Affiliation(s)
- Ardha Apriyanto
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, 14476 Potsdam-Golm, Germany
| | - Julia Compart
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, 14476 Potsdam-Golm, Germany
| | - Joerg Fettke
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, 14476 Potsdam-Golm, Germany.
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7
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Nakamura Y, Kainuma K. On the cluster structure of amylopectin. PLANT MOLECULAR BIOLOGY 2022; 108:291-306. [PMID: 34599732 DOI: 10.1007/s11103-021-01183-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 08/15/2021] [Indexed: 05/21/2023]
Abstract
Two opposing models for the amylopectin structure are historically and comprehensively reviewed, which leads us to a better understanding of the specific fine structure of amylopectin. Amylopectin is a highly branched glucan which accounts for approximately 65-85 of starch in most plant tissues. However, its fine structure is still not fully understood due to the limitations of current methodologies. Since the 1940 s, many scientists have attempted to elucidate the distinct structure of amylopectin. One of the most accepted concepts is that amylopectin has a structural element known as "cluster", in which neighboring side chains with a degree of polymerization of ≥ 10 in the region of their non-branched segments form double helices. The double helical structures are arranged in inter- and intra-clusters and are the origin of the distinct physicochemical and crystalline properties of starch granules. Several models of the cluster structure have been proposed by starch scientists worldwide during the progress of analytical methods, whereas no direct evidence so far has been provided. Recently, Bertoft and colleagues proposed a new model designated as "the building block and backbone (BB) model". The BB model sharply contrasts with the cluster model in that the structural element for the BB model is the building block, and that long chains are separately synthesized and positioned from short chains constituting the building block. In the present paper, we conduct the historical review of the cluster concept detailing how and when the concept was established based on experimental results by many scientists. Then, differences between the two opposing concepts are explained and both models are critically discussed, particularly from the point of view of the biochemical regulation of amylopectin biosynthesis.
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Affiliation(s)
- Yasunori Nakamura
- Starch Technologies, Co., Ltd, Akita Prefectural University, Shimoshinjo-Nakano, Akita-city, Akita, 010-0195, Japan.
- Akita Natural Science Laboratory, 25-44 Oiwake-Nishi, Tennoh, Katagami, Akita, 010-0101, Japan.
| | - Keiji Kainuma
- Science Academy of Tsukuba, 2-20-3 Takezono, Tsukuba, Ibaraki, 305-0032, Japan
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8
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Huang L, Tan H, Zhang C, Li Q, Liu Q. Starch biosynthesis in cereal endosperms: An updated review over the last decade. PLANT COMMUNICATIONS 2021; 2:100237. [PMID: 34746765 PMCID: PMC8554040 DOI: 10.1016/j.xplc.2021.100237] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 08/08/2021] [Accepted: 08/27/2021] [Indexed: 05/13/2023]
Abstract
Starch is a vital energy source for living organisms and is a key raw material and additive in the food and non-food industries. Starch has received continuous attention in multiple research fields. The endosperm of cereals (e.g., rice, corn, wheat, and barley) is the most important site for the synthesis of storage starch. Around 2010, several excellent reviews summarized key progress in various fields of starch research, serving as important references for subsequent research. In the past 10 years, many achievements have been made in the study of starch synthesis and regulation in cereals. The present review provides an update on research progress in starch synthesis of cereal endosperms over the past decade, focusing on new enzymes and non-enzymatic proteins involved in starch synthesis, regulatory networks of starch synthesis, and the use of elite alleles of starch synthesis-related genes in cereal breeding programs. We also provide perspectives on future research directions that will further our understanding of cereal starch biosynthesis and regulation to support the rational design of ideal quality grain.
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Affiliation(s)
- Lichun Huang
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, State Key Laboratory of Hybrid Rice, Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China
- Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province, Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou 225009, China
| | - Hongyan Tan
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, State Key Laboratory of Hybrid Rice, Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China
| | - Changquan Zhang
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, State Key Laboratory of Hybrid Rice, Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China
- Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province, Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou 225009, China
| | - Qianfeng Li
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, State Key Laboratory of Hybrid Rice, Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China
- Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province, Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou 225009, China
| | - Qiaoquan Liu
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, State Key Laboratory of Hybrid Rice, Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China
- Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province, Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou 225009, China
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Mérida A, Fettke J. Starch granule initiation in Arabidopsis thaliana chloroplasts. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 107:688-697. [PMID: 34051021 DOI: 10.1111/tpj.15359] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/14/2021] [Accepted: 05/22/2021] [Indexed: 06/12/2023]
Abstract
The initiation of starch granule formation and the mechanism controlling the number of granules per plastid have been some of the most elusive aspects of starch metabolism. This review covers the advances made in the study of these processes. The analyses presented herein depict a scenario in which starch synthase isoform 4 (SS4) provides the elongating activity necessary for the initiation of starch granule formation. However, this protein does not act alone; other polypeptides are required for the initiation of an appropriate number of starch granules per chloroplast. The functions of this group of polypeptides include providing suitable substrates (maltooligosaccharides) to SS4, the localization of the starch initiation machinery to the thylakoid membranes, and facilitating the correct folding of SS4. The number of starch granules per chloroplast is tightly regulated and depends on the developmental stage of the leaves and their metabolic status. Plastidial phosphorylase (PHS1) and other enzymes play an essential role in this process since they are necessary for the synthesis of the substrates used by the initiation machinery. The mechanism of starch granule formation initiation in Arabidopsis seems to be generalizable to other plants and also to the synthesis of long-term storage starch. The latter, however, shows specific features due to the presence of more isoforms, the absence of constantly recurring starch synthesis and degradation, and the metabolic characteristics of the storage sink organs.
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Affiliation(s)
- Angel Mérida
- Institute of Plant Biochemistry and Photosynthesis (IBVF), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Sevilla (US), Avda Américo Vespucio, 49, Sevilla, 41092, Spain
| | - Joerg Fettke
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, Potsdam-Golm, 14476, Germany
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10
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Hawkins E, Chen J, Watson-Lazowski A, Ahn-Jarvis J, Barclay JE, Fahy B, Hartley M, Warren FJ, Seung D. STARCH SYNTHASE 4 is required for normal starch granule initiation in amyloplasts of wheat endosperm. THE NEW PHYTOLOGIST 2021; 230:2371-2386. [PMID: 33714222 DOI: 10.1111/nph.17342] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 03/05/2021] [Indexed: 05/26/2023]
Abstract
Starch granule initiation is poorly understood at the molecular level. The glucosyltransferase, STARCH SYNTHASE 4 (SS4), plays a central role in granule initiation in Arabidopsis leaves, but its function in cereal endosperms is unknown. We investigated the role of SS4 in wheat, which has a distinct spatiotemporal pattern of granule initiation during grain development. We generated TILLING mutants in tetraploid wheat (Triticum turgidum) that are defective in both SS4 homoeologs. The morphology of endosperm starch was examined in developing and mature grains. SS4 deficiency led to severe alterations in endosperm starch granule morphology. During early grain development, while the wild-type initiated single 'A-type' granules per amyloplast, most amyloplasts in the mutant formed compound granules due to multiple initiations. This phenotype was similar to mutants deficient in B-GRANULE CONTENT 1 (BGC1). SS4 deficiency also reduced starch content in leaves and pollen grains. We propose that SS4 and BGC1 are required for the proper control of granule initiation during early grain development that leads to a single A-type granule per amyloplast. The absence of either protein results in a variable number of initiations per amyloplast and compound granule formation.
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Affiliation(s)
- Erica Hawkins
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Jiawen Chen
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | | | | | | | - Brendan Fahy
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Matthew Hartley
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | | | - David Seung
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
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11
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Seung D. Amylose in starch: towards an understanding of biosynthesis, structure and function. THE NEW PHYTOLOGIST 2020; 228:1490-1504. [PMID: 32767769 DOI: 10.1111/nph.16858] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/13/2020] [Indexed: 05/20/2023]
Abstract
Starch granules are composed of two distinct glucose polymers - amylose and amylopectin. Amylose constitutes 5-35% of most natural starches and has a major influence over starch properties in foods. Its synthesis and storage occurs within the semicrystalline amylopectin matrix of starch granules, this poses a great challenge for biochemical and structural analyses. However, the last two decades have seen vast progress in understanding amylose synthesis, including new insights into the action of GRANULE BOUND STARCH SYNTHASE (GBSS), the major glucosyltransferase that synthesises amylose, and the discovery of PROTEIN TARGETING TO STARCH1 (PTST1) that targets GBSS to starch granules. Advances in analytical techniques have resolved the fine structure of amylose, raising new questions on how structure is determined during biosynthesis. Furthermore, the discovery of wild plants that do not produce amylose revives a long-standing question of why starch granules contain amylose, rather than amylopectin alone. Overall, these findings contribute towards a full understanding of amylose biosynthesis, structure and function that will be essential for future approaches to improve starch quality in crops.
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Affiliation(s)
- David Seung
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
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12
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Zuo Y, Feng F, Qi W, Song R. Dek42 encodes an RNA-binding protein that affects alternative pre-mRNA splicing and maize kernel development. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2019; 61:728-748. [PMID: 30839161 DOI: 10.1111/jipb.12798] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/28/2019] [Indexed: 05/22/2023]
Abstract
RNA-binding proteins (RBPs) play an important role in post-transcriptional gene regulation. However, the functions of RBPs in plants remain poorly understood. Maize kernel mutant dek42 has small defective kernels and lethal seedlings. Dek42 was cloned by Mutator tag isolation and further confirmed by an independent mutant allele and clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 materials. Dek42 encodes an RRM_RBM48 type RNA-binding protein that localizes to the nucleus. Dek42 is constitutively expressed in various maize tissues. The dek42 mutation caused a significant reduction in the accumulation of DEK42 protein in mutant kernels. RNA-seq analysis showed that the dek42 mutation significantly disturbed the expression of thousands of genes during maize kernel development. Sequence analysis also showed that the dek42 mutation significantly changed alternative splicing in expressed genes, which were especially enriched for the U12-type intron-retained type. Yeast two-hybrid screening identified SF3a1 as a DEK42-interacting protein. DEK42 also interacts with the spliceosome component U1-70K. These results suggested that DEK42 participates in the regulation of pre-messenger RNA splicing through its interaction with other spliceosome components. This study showed the function of a newly identified RBP and provided insights into alternative splicing regulation during maize kernel development.
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Affiliation(s)
- Yi Zuo
- State Key Laboratory of Plant Physiology and Biochemistry, National Maize Improvement Center, Beijing Key Laboratory of Crop Genetic Improvement, Joint International Research Laboratory of Crop Molecular Breeding, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
| | - Fan Feng
- Shanghai Key Laboratory of Bio-Energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Weiwei Qi
- Shanghai Key Laboratory of Bio-Energy Crops, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Rentao Song
- State Key Laboratory of Plant Physiology and Biochemistry, National Maize Improvement Center, Beijing Key Laboratory of Crop Genetic Improvement, Joint International Research Laboratory of Crop Molecular Breeding, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China
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13
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Seung D, Smith AM. Starch granule initiation and morphogenesis-progress in Arabidopsis and cereals. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:771-784. [PMID: 30452691 DOI: 10.1093/jxb/ery412] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 11/06/2018] [Indexed: 05/13/2023]
Abstract
Starch, the major storage carbohydrate in plants, is synthesized in plastids as semi-crystalline, insoluble granules. Many organs and cell types accumulate starch at some point during their development and maturation. The biosynthesis of the starch polymers, amylopectin and amylose, is relatively well understood and mostly conserved between organs and species. However, we are only beginning to understand the mechanism by which starch granules are initiated, and the factors that control the number of granules per plastid and the size/shape of granules. Here, we review recent progress in understanding starch granule initiation and morphogenesis. In Arabidopsis, granule initiation requires several newly discovered proteins with specific locations within the chloroplast, and also on the availability of maltooligosaccharides which act as primers for initiation. We also describe progress in understanding granule biogenesis in the endosperm of cereal grains-within which there is large interspecies variation in granule initiation patterns and morphology. Investigating whether this diversity results from differences between species in the functions of known proteins, and/or from the presence of novel, unidentified proteins, is a promising area of future research. Expanding our knowledge in these areas will lead to new strategies for improving the quality of cereal crops by modifying starch granule size and shape in vivo.
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Affiliation(s)
- David Seung
- John Innes Centre, Norwich Research Park, Norwich, UK
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14
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Goren A, Ashlock D, Tetlow IJ. Starch formation inside plastids of higher plants. PROTOPLASMA 2018; 255:1855-1876. [PMID: 29774409 DOI: 10.1007/s00709-018-1259-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/03/2018] [Indexed: 05/09/2023]
Abstract
Starch is a water-insoluble polyglucan synthesized inside the plastid stroma within plant cells, serving a crucial role in the carbon budget of the whole plant by acting as a short-term and long-term store of energy. The highly complex, hierarchical structure of the starch granule arises from the actions of a large suite of enzyme activities, in addition to physicochemical self-assembly mechanisms. This review outlines current knowledge of the starch biosynthetic pathway operating in plant cells in relation to the micro- and macro-structures of the starch granule. We highlight the gaps in our knowledge, in particular, the relationship between enzyme function and operation at the molecular level and the formation of the final, macroscopic architecture of the granule.
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Affiliation(s)
- Asena Goren
- Department of Mathematics and Statistics, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Daniel Ashlock
- Department of Mathematics and Statistics, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Ian J Tetlow
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
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15
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Xie Y, Barb AW, Hennen-Bierwagen TA, Myers AM. Direct Determination of the Site of Addition of Glucosyl Units to Maltooligosaccharide Acceptors Catalyzed by Maize Starch Synthase I. FRONTIERS IN PLANT SCIENCE 2018; 9:1252. [PMID: 30233610 PMCID: PMC6127246 DOI: 10.3389/fpls.2018.01252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 08/07/2018] [Indexed: 06/08/2023]
Abstract
Starch synthase (SS) (ADP-glucose:1,4-α-D-glucan 4-α-D-glucosyltransferase) elongates α-(1→4)-linked linear glucans within plastids to generate the storage polymers that constitute starch granules. Multiple SS classes are conserved throughout the plant kingdom, indicating that each provides a unique function responsible for evolutionary selection. Evidence has been presented arguing for addition of glucosyl units from the ADPglucose donor to either the reducing end or the non-reducing end of the acceptor substrate, although until recently direct evidence addressing this question was not available. Characterization of newly incorporated glucosyl units determined that recombinant maize (Zea mays L.) SSIIa elongates its substrates at the non-reducing end. However, the possibility remained that other SSs might utilize distinct mechanisms, and that one or more of the conserved enzyme classes could elongate acceptors at the reducing end. This study characterized the reaction mechanism of recombinant maize SSI regarding its addition site. Newly incorporated residues were labeled with 13C, and reducing ends of the elongation products were labeled by chemical derivitization. Electrospray ionization-tandem mass spectroscopy traced the two parameters, i.e., the newly added residue and the reducing end. The results determined that SSI elongates glucans at the non-reducing end. The study also confirmed previous findings showing recombinant SSI can generate glucans of at least 25 units, that it is active using acceptors as short as maltotriose, that recombinant forms of the enzyme absolutely require an acceptor for activity, and that it is not saturable with maltooligosaccharide acceptor substrates.
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Affiliation(s)
- Ying Xie
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA, United States
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Adam W. Barb
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA, United States
| | - Tracie A. Hennen-Bierwagen
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA, United States
| | - Alan M. Myers
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA, United States
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16
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Qu J, Xu S, Zhang Z, Chen G, Zhong Y, Liu L, Zhang R, Xue J, Guo D. Evolutionary, structural and expression analysis of core genes involved in starch synthesis. Sci Rep 2018; 8:12736. [PMID: 30143668 PMCID: PMC6109180 DOI: 10.1038/s41598-018-30411-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 07/30/2018] [Indexed: 01/29/2023] Open
Abstract
Starch is the main storage carbohydrate in plants and an important natural resource for food, feed and industrial raw materials. However, the details regarding the pathway for starch biosynthesis and the diversity of biosynthetic enzymes involved in this process are poorly understood. This study uses a comprehensive phylogenetic analysis of 74 sequenced plant genomes to revisit the evolutionary history of the genes encoding ADP-glucose pyrophosphorylase (AGPase), starch synthase (SS), starch branching enzyme (SBE) and starch de-branching enzyme (DBE). Additionally, the protein structures and expression patterns of these four core genes in starch biosynthesis were studied to determine their functional differences. The results showed that AGPase, SS, SBE and DBE have undergone complicated evolutionary processes in plants and that gene/genome duplications are responsible for the observed differences in isoform numbers. A structure analysis of these proteins suggested that the deletion/mutation of amino acids in some active sites resulted in not only structural variation but also sub-functionalization or neo-functionalization. Expression profiling indicated that AGPase-, SS-, SBE- and DBE-encoding genes exhibit spatio-temporally divergent expression patterns related to the composition of functional complexes in starch biosynthesis. This study provides a comprehensive atlas of the starch biosynthetic pathway, and these data should support future studies aimed at increasing understanding of starch biosynthesis and the functional evolutionary divergence of AGPase, SS, SBE, and DBE in plants.
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Affiliation(s)
- Jianzhou Qu
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China
| | - Shutu Xu
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China
| | - Zhengquan Zhang
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China
| | - Guangzhou Chen
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China
| | - Yuyue Zhong
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China
| | - Linsan Liu
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China
| | - Renhe Zhang
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China
| | - Jiquan Xue
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China.
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China.
| | - Dongwei Guo
- The key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China.
- Maize Engineering Technology Research Centre of Shaanxi Province, Yangling, 712100, Shaanxi, China.
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17
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Malinova I, Qasim HM, Brust H, Fettke J. Parameters of Starch Granule Genesis in Chloroplasts of Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2018; 9:761. [PMID: 29922326 PMCID: PMC5996153 DOI: 10.3389/fpls.2018.00761] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/17/2018] [Indexed: 05/16/2023]
Abstract
Starch is the primary storage carbohydrate in most photosynthetic organisms and allows the accumulation of carbon and energy in form of an insoluble and semi-crystalline particle. In the last decades large progress, especially in the model plant Arabidopsis thaliana, was made in understanding the structure and metabolism of starch and its conjunction. The process underlying the initiation of starch granules remains obscure, although this is a fundamental process and seems to be strongly regulated, as in Arabidopsis leaves the starch granule number per chloroplast is fixed with 5-7. Several single, double, and triple mutants were reported in the last years that showed massively alterations in the starch granule number per chloroplast and allowed further insights in this important process. This mini review provides an overview of the current knowledge of processes involved in the initiation and formation of starch granules. We discuss the central role of starch synthase 4 and further proteins for starch genesis and affecting metabolic factors.
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Affiliation(s)
- Irina Malinova
- Present address: Irina Malinova, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany Henrike Brust, Plasma Agriculture, Leibniz-Institute for Plasma Science and Technology, Greifswald, Germany
| | | | - Henrike Brust
- Present address: Irina Malinova, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany Henrike Brust, Plasma Agriculture, Leibniz-Institute for Plasma Science and Technology, Greifswald, Germany
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18
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Functional and structural characterization of plastidic starch phosphorylase during barley endosperm development. PLoS One 2017; 12:e0175488. [PMID: 28407006 PMCID: PMC5391026 DOI: 10.1371/journal.pone.0175488] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 03/27/2017] [Indexed: 12/03/2022] Open
Abstract
The production of starch is essential for human nutrition and represents a major metabolic flux in the biosphere. The biosynthesis of starch in storage organs like barley endosperm operates via two main pathways using different substrates: starch synthases use ADP-glucose to produce amylose and amylopectin, the two major components of starch, whereas starch phosphorylase (Pho1) uses glucose-1-phosphate (G1P), a precursor for ADP-glucose production, to produce α-1,4 glucans. The significance of the Pho1 pathway in starch biosynthesis has remained unclear. To elucidate the importance of barley Pho1 (HvPho1) for starch biosynthesis in barley endosperm, we analyzed HvPho1 protein production and enzyme activity levels throughout barley endosperm development and characterized structure-function relationships of HvPho1. The molecular mechanisms underlying the initiation of starch granule biosynthesis, that is, the enzymes and substrates involved in the initial transition from simple sugars to polysaccharides, remain unclear. We found that HvPho1 is present as an active protein at the onset of barley endosperm development. Notably, purified recombinant protein can catalyze the de novo production of α-1,4-glucans using HvPho1 from G1P as the sole substrate. The structural properties of HvPho1 provide insights into the low affinity of HvPho1 for large polysaccharides like starch or amylopectin. Our results suggest that HvPho1 may play a role during the initiation of starch biosynthesis in barley.
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19
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Eicke S, Seung D, Egli B, Devers EA, Streb S. Increasing the carbohydrate storage capacity of plants by engineering a glycogen-like polymer pool in the cytosol. Metab Eng 2017; 40:23-32. [PMID: 28216105 DOI: 10.1016/j.ymben.2017.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/09/2017] [Accepted: 02/14/2017] [Indexed: 01/15/2023]
Abstract
Global demand for higher crop yields and for more efficient utilization of agricultural products will grow over the next decades. Here, we present a new concept for boosting the carbohydrate content of plants, by channeling photosynthetically fixed carbon into a newly engineered glucose polymer pool. We transiently expressed the starch/glycogen synthases from either Saccharomyces cerevisiae or Cyanidioschyzon merolae, together with the starch branching enzyme from C. merolae, in the cytosol of Nicotiana benthamiana leaves. This effectively built a UDP-glucose-dependent glycogen biosynthesis pathway. Glycogen synthesis was observed with Transmission Electron Microscopy, and the polymer structure was further analyzed. Within three days of enzyme expression, glycogen content of the leaf was 5-10 times higher than the starch levels of the control. Further, the leaves produced less starch and sucrose, which are normally the carbohydrate end-products of photosynthesis. We conclude that after enzyme expression, the newly fixed carbohydrates were routed into the new glycogen sink and trapped. Our approach allows carbohydrates to be efficiently stored in a new subcellular compartment, thus increasing the value of vegetative crop tissues for biofuel production or animal feed. The method also opens new potential for increasing the sink strength of heterotrophic tissues.
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Affiliation(s)
- Simona Eicke
- Institute for Agricultural Sciences, Plant Biochemistry, ETH Zurich, CH-8092 Zurich, Switzerland
| | - David Seung
- Institute for Agricultural Sciences, Plant Biochemistry, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Barbara Egli
- Institute for Agricultural Sciences, Plant Biochemistry, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Emanuel A Devers
- Institute for Agricultural Sciences, Plant Biochemistry, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Sebastian Streb
- Institute for Agricultural Sciences, Plant Biochemistry, ETH Zurich, CH-8092 Zurich, Switzerland.
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20
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Nazarian-Firouzabadi F, Visser RGF. Potato starch synthases: Functions and relationships. Biochem Biophys Rep 2017; 10:7-16. [PMID: 29114568 PMCID: PMC5637242 DOI: 10.1016/j.bbrep.2017.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 02/01/2017] [Accepted: 02/03/2017] [Indexed: 01/28/2023] Open
Abstract
Starch, a very compact form of glucose units, is the most abundant form of storage polyglucan in nature. The starch synthesis pathway is among the central biochemical pathways, however, our understanding of this important pathway regarding genetic elements controlling this pathway, is still insufficient. Starch biosynthesis requires the action of several enzymes. Soluble starch synthases (SSs) are a group of key players in starch biosynthesis which have proven their impact on different aspects of the starch biosynthesis and functionalities. These enzymes have been studied in different plant species and organs in detail, however, there seem to be key differences among species regarding their contributions to the starch synthesis. In this review, we consider an update on various SSs with an emphasis on potato SSs as a model for storage organs. The genetics and regulatory mechanisms of potato starch synthases will be highlighted. Different aspects of various isoforms of SSs are also discussed.
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Affiliation(s)
- Farhad Nazarian-Firouzabadi
- Agronomy and Plant Breeding Department, Faculty of Agriculture, Lorestan University, P.O.Box 465, Khorramabad, Iran
| | - Richard G F Visser
- Plant Breeding, Wageningen University & Research, P.O. Box 386, 6700 AJ, Wageningen, The Netherlands
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21
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Abstract
Starch-rich crops form the basis of our nutrition, but plants have still to yield all their secrets as to how they make this vital substance. Great progress has been made by studying both crop and model systems, and we approach the point of knowing the enzymatic machinery responsible for creating the massive, insoluble starch granules found in plant tissues. Here, we summarize our current understanding of these biosynthetic enzymes, highlighting recent progress in elucidating their specific functions. Yet, in many ways we have only scratched the surface: much uncertainty remains about how these components function together and are controlled. We flag-up recent observations suggesting a significant degree of flexibility during the synthesis of starch and that previously unsuspected non-enzymatic proteins may have a role. We conclude that starch research is not yet a mature subject and that novel experimental and theoretical approaches will be important to advance the field.
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Affiliation(s)
- Barbara Pfister
- Department of Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Samuel C Zeeman
- Department of Biology, ETH Zurich, 8092, Zurich, Switzerland.
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22
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Orawetz T, Malinova I, Orzechowski S, Fettke J. Reduction of the plastidial phosphorylase in potato (Solanum tuberosum L.) reveals impact on storage starch structure during growth at low temperature. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 100:141-149. [PMID: 26828405 DOI: 10.1016/j.plaphy.2016.01.013] [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] [Received: 11/02/2015] [Revised: 01/15/2016] [Accepted: 01/18/2016] [Indexed: 05/26/2023]
Abstract
Tubers of potato (Solanum tuberosum L.), one of the most important crops, are a prominent example for an efficient production of storage starch. Nevertheless, the synthesis of this storage starch is not completely understood. The plastidial phosphorylase (Pho1; EC 2.4.1.1) catalyzes the reversible transfer of glucosyl residues from glucose-1-phosphate to the non-reducing end of α-glucans with the release of orthophosphate. Thus, the enzyme is in principle able to act during starch synthesis. However, so far under normal growth conditions no alterations in tuber starch metabolism were observed. Based on analyses of other species and also from in vitro experiments with potato tuber slices it was supposed, that Pho1 has a stronger impact on starch metabolism, when plants grow under low temperature conditions. Therefore, we analyzed the starch content, granule size, as well as the internal structure of starch granules isolated from potato plants grown under low temperatures. Besides wild type, transgenic potato plants with a strong reduction in the Pho1 activity were analyzed. No significant alterations in starch content and granule size were detected. In contrast, when plants were cultivated at low temperatures the chain length distributions of the starch granules were altered. Thus, the granules contained more short glucan chains. That was not observed in the transgenic plants, revealing that Pho1 in wild type is involved in the formation of the short glucan chains, at least at low temperatures.
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Affiliation(s)
- Tom Orawetz
- Biopolymer Analytics, University of Potsdam, Potsdam-Golm, Germany
| | - Irina Malinova
- Biopolymer Analytics, University of Potsdam, Potsdam-Golm, Germany
| | - Slawomir Orzechowski
- Department of Biochemistry, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Joerg Fettke
- Biopolymer Analytics, University of Potsdam, Potsdam-Golm, Germany; Department of Biochemistry, Warsaw University of Life Sciences - SGGW, Warsaw, Poland.
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23
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Cuesta-Seijo JA, Nielsen MM, Ruzanski C, Krucewicz K, Beeren SR, Rydhal MG, Yoshimura Y, Striebeck A, Motawia MS, Willats WGT, Palcic MM. In vitro Biochemical Characterization of All Barley Endosperm Starch Synthases. FRONTIERS IN PLANT SCIENCE 2016; 6:1265. [PMID: 26858729 PMCID: PMC4730117 DOI: 10.3389/fpls.2015.01265] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/27/2015] [Indexed: 05/18/2023]
Abstract
Starch is the main storage polysaccharide in cereals and the major source of calories in the human diet. It is synthesized by a panel of enzymes including five classes of starch synthases (SSs). While the overall starch synthase (SS) reaction is known, the functional differences between the five SS classes are poorly understood. Much of our knowledge comes from analyzing mutant plants with altered SS activities, but the resulting data are often difficult to interpret as a result of pleitropic effects, competition between enzymes, overlaps in enzyme activity and disruption of multi-enzyme complexes. Here we provide a detailed biochemical study of the activity of all five classes of SSs in barley endosperm. Each enzyme was produced recombinantly in E. coli and the properties and modes of action in vitro were studied in isolation from other SSs and other substrate modifying activities. Our results define the mode of action of each SS class in unprecedented detail; we analyze their substrate selection, temperature dependence and stability, substrate affinity and temporal abundance during barley development. Our results are at variance with some generally accepted ideas about starch biosynthesis and might lead to the reinterpretation of results obtained in planta. In particular, they indicate that granule bound SS is capable of processive action even in the absence of a starch matrix, that SSI has no elongation limit, and that SSIV, believed to be critical for the initiation of starch granules, has maltoligosaccharides and not polysaccharides as its preferred substrates.
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Affiliation(s)
| | | | | | | | | | - Maja G. Rydhal
- Department of Plant and Environmental Sciences, University of CopenhagenFrederiksberg, Copenhagen, Denmark
| | | | | | - Mohammed S. Motawia
- Department of Plant and Environmental Sciences, University of CopenhagenFrederiksberg, Copenhagen, Denmark
| | - William G. T. Willats
- Department of Plant and Environmental Sciences, University of CopenhagenFrederiksberg, Copenhagen, Denmark
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24
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Liu H, Yu G, Wei B, Wang Y, Zhang J, Hu Y, Liu Y, Yu G, Zhang H, Huang Y. Identification and Phylogenetic Analysis of a Novel Starch Synthase in Maize. FRONTIERS IN PLANT SCIENCE 2015; 6:1013. [PMID: 26635839 PMCID: PMC4653816 DOI: 10.3389/fpls.2015.01013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/02/2015] [Indexed: 05/02/2023]
Abstract
Starch is an important reserve of carbon and energy in plants, providing the majority of calories in the human diet and animal feed. Its synthesis is orchestrated by several key enzymes, and the amount and structure of starch, affecting crop yield and quality, are determined mainly by starch synthase (SS) activity. To date, five SS isoforms, including SSI-IV and Granule Bound Starch Synthase (GBSS) have been identified and their physiological functions have been well characterized. Here, we report the identification of a new SS isoform in maize, designated SSV. By searching sequenced genomes, SSV has been found in all green plants with conserved sequences and gene structures. Our phylogenetic analysis based on 780 base pairs has suggested that SSIV and SSV resulted from a gene duplication event, which may have occurred before the algae formation. An expression profile analysis of SSV in maize has indicated that ZmSSV is mainly transcribed in the kernel and ear leaf during the grain filling stage, which is partly similar to other SS isoforms. Therefore, it is likely that SSV may play an important role in starch biosynthesis. Subsequent analysis of SSV function may facilitate understanding the mechanism of starch granules formation, number and structure.
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Affiliation(s)
- Hanmei Liu
- College of Life Science, Sichuan Agricultural UniversityYa’an, China
| | - Guiling Yu
- College of Life Science, Sichuan Agricultural UniversityYa’an, China
| | - Bin Wei
- Maize Research Institute, Sichuan Agricultural UniversityChengdu, China
| | - Yongbin Wang
- Maize Research Institute, Sichuan Agricultural UniversityChengdu, China
| | - Junjie Zhang
- College of Life Science, Sichuan Agricultural UniversityYa’an, China
| | - Yufeng Hu
- College of Agronomy, Sichuan Agricultural UniversityChengdu, China
| | - Yinghong Liu
- Maize Research Institute, Sichuan Agricultural UniversityChengdu, China
| | - Guowu Yu
- College of Agronomy, Sichuan Agricultural UniversityChengdu, China
| | - Huaiyu Zhang
- College of Life Science, Sichuan Agricultural UniversityYa’an, China
| | - Yubi Huang
- Maize Research Institute, Sichuan Agricultural UniversityChengdu, China
- College of Agronomy, Sichuan Agricultural UniversityChengdu, China
- *Correspondence: Yubi Huang,
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25
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Brust H, Lehmann T, D'Hulst C, Fettke J. Analysis of the functional interaction of Arabidopsis starch synthase and branching enzyme isoforms reveals that the cooperative action of SSI and BEs results in glucans with polymodal chain length distribution similar to amylopectin. PLoS One 2014; 9:e102364. [PMID: 25014622 PMCID: PMC4094495 DOI: 10.1371/journal.pone.0102364] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 06/18/2014] [Indexed: 01/17/2023] Open
Abstract
Starch synthase (SS) and branching enzyme (BE) establish the two glycosidic linkages existing in starch. Both enzymes exist as several isoforms. Enzymes derived from several species were studied extensively both in vivo and in vitro over the last years, however, analyses of a functional interaction of SS and BE isoforms are missing so far. Here, we present data from in vitro studies including both interaction of leaf derived and heterologously expressed SS and BE isoforms. We found that SSI activity in native PAGE without addition of glucans was dependent on at least one of the two BE isoforms active in Arabidopsis leaves. This interaction is most likely not based on a physical association of the enzymes, as demonstrated by immunodetection and native PAGE mobility analysis of SSI, BE2, and BE3. The glucans formed by the action of SSI/BEs were analysed using leaf protein extracts from wild type and be single mutants (Atbe2 and Atbe3 mutant lines) and by different combinations of recombinant proteins. Chain length distribution (CLD) patterns of the formed glucans were irrespective of SSI and BE isoforms origin and still independent of assay conditions. Furthermore, we show that all SS isoforms (SSI-SSIV) were able to interact with BEs and form branched glucans. However, only SSI/BEs generated a polymodal distribution of glucans which was similar to CLD pattern detected in amylopectin of Arabidopsis leaf starch. We discuss the impact of the SSI/BEs interplay for the CLD pattern of amylopectin.
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Affiliation(s)
- Henrike Brust
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
- * E-mail:
| | - Tanja Lehmann
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
| | - Christophe D'Hulst
- Unité de Glycobiologie Structurale et Fonctionnelle, Université Lille1, Villeneuve d'Ascq, France
| | - Joerg Fettke
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
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Mahlow S, Hejazi M, Kuhnert F, Garz A, Brust H, Baumann O, Fettke J. Phosphorylation of transitory starch by α-glucan, water dikinase during starch turnover affects the surface properties and morphology of starch granules. THE NEW PHYTOLOGIST 2014; 203:495-507. [PMID: 24697163 DOI: 10.1111/nph.12801] [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: 11/27/2013] [Accepted: 03/07/2014] [Indexed: 05/09/2023]
Abstract
Glucan, water dikinase (GWD) is a key enzyme of starch metabolism but the physico-chemical properties of starches isolated from GWD-deficient plants and their implications for starch metabolism have so far not been described. Transgenic Arabidopsis thaliana plants with reduced or no GWD activity were used to investigate the properties of starch granules. In addition, using various in vitro assays, the action of recombinant GWD, β-amylase, isoamylase and starch synthase 1 on the surface of native starch granules was analysed. The internal structure of granules isolated from GWD mutant plants is unaffected, as thermal stability, allomorph, chain length distribution and density of starch granules were similar to wild-type. However, short glucan chain residues located at the granule surface dominate in starches of transgenic plants and impede GWD activity. A similarly reduced rate of phosphorylation by GWD was also observed in potato tuber starch fractions that differ in the proportion of accessible glucan chain residues at the granule surface. A model is proposed to explain the characteristic morphology of starch granules observed in GWD transgenic plants. The model postulates that the occupancy rate of single glucan chains at the granule surface limits accessibility to starch-related enzymes.
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Affiliation(s)
- Sebastian Mahlow
- Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
- Biopolymers Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Mahdi Hejazi
- Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Franziska Kuhnert
- Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Andreas Garz
- Photonics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Henrike Brust
- Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Otto Baumann
- Zoophysiology, Institute of Biochemistry and Biology, University of Potdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Joerg Fettke
- Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
- Biopolymers Analytics, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
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