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Patel HP, Martinez‐Ramirez G, Dobrzynski E, Iglesias AA, Liu D, Ballicora MA. A critical inter-subunit interaction for the transmission of the allosteric signal in the Agrobacterium tumefaciens ADP-glucose pyrophosphorylase. Protein Sci 2023; 32:e4747. [PMID: 37551561 PMCID: PMC10461462 DOI: 10.1002/pro.4747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/20/2023] [Accepted: 08/04/2023] [Indexed: 08/09/2023]
Abstract
ADP-glucose pyrophosphorylase is a key regulatory enzyme involved in starch and glycogen synthesis in plants and bacteria, respectively. It has been hypothesized that inter-subunit communications are important for the allosteric effect in this enzyme. However, no specific interactions have been identified as part of the regulatory signal. The enzyme from Agrobacterium tumefaciens is a homotetramer allosterically regulated by fructose 6-phosphate and pyruvate. Three pairs of distinct subunit-subunit interfaces are present. Here we focus on an interface that features two symmetrical interactions between Arg11 and Asp141 from one subunit with residues Asp141 and Arg11 of the neighbor subunit, respectively. Previously, scanning mutagenesis showed that a mutation at the Arg11 position disrupted the activation of the enzyme. Considering the distance of these residues from the allosteric and catalytic sites, we hypothesized that the interaction between Arg11 and Asp141 is critical for allosteric signaling rather than effector binding. To prove our hypothesis, we mutated those two sites (D141A, D141E, D141N, D141R, R11D, and R11K) and performed kinetic and binding analysis. Mutations that altered the charge affected the regulation the most. To prove that the interaction per se (rather than the presence of specific residues) is critical, we partially rescued the R11D protein by introducing a second mutation (R11D/D141R). This could not restore the activator effect on kcat , but it did rescue the effect on substrate affinity. Our results indicate the critical functional role of Arg11 and Asp141 to relay the allosteric signal in this subunit interface.
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Affiliation(s)
- Hiral P. Patel
- Department of Chemistry and BiochemistryLoyola University ChicagoChicagoIllinoisUSA
| | | | - Emily Dobrzynski
- Department of Chemistry and BiochemistryLoyola University ChicagoChicagoIllinoisUSA
| | | | - Dali Liu
- Department of Chemistry and BiochemistryLoyola University ChicagoChicagoIllinoisUSA
| | - Miguel A. Ballicora
- Department of Chemistry and BiochemistryLoyola University ChicagoChicagoIllinoisUSA
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Wang C, Jiang H, Gao G, Yang F, Guan J, Qi H. CmMYB44 might interact with CmAPS2-2 to regulate starch metabolism in oriental melon fruit. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 196:361-369. [PMID: 36739843 DOI: 10.1016/j.plaphy.2023.01.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/13/2023] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Sugar content is one of the determining factors for melon fruit maturity. Studies have shown that starch gradually degrades during fruit ripening, resulting in sugar accumulation. But the specific relationship between starch metabolism and sucrose accumulation was still unknown. Here, the starch and sugar contents, the activities of key enzymes and the expression patterns of genes related to starch-sucrose metabolism were determined in the fruit of high sugar and starch variety 'HS' and low sugar and starch variety 'LW'. It was found that starch accumulated during fruit development process, and then degraded at 30 days after anthesis (DAA), which was synchronized with sucrose accumulation in 'HS' fruit, while starch and sucrose contents were always at a lower level during 'LW' fruit maturation. Furthermore, starch metabolism-related enzymes (Adenine dinucleotide phosphate -glucose pyrophosphorylase (AGPase), α-amylase (AMY), β-amylase (BMY)) and the key enzymes for sucrose accumulation (sucrose phosphate synthase (SPS) and sucrose synthase (SS)) were significantly increased at ripening stage of 'HS' fruit, and their activities were consistent with the expressions of CmAPS2-2, CmAMY2, CmBAM1, CmBAM9 and CmSPS1. However, the contents of starch and sucrose and the activities of AGPase and SPS in 'LW' fruit didn't change significantly. We discovered an R2R3-type MYB transcription factor, CmMYB44, screened from yeast one hybrid library, could directly bind to the promoter of CmAPS2-2 to inhibit its transcription. These results revealed that the targeted down-regulation of CmAPS2-2 by CmMYB44 might be involved in the starch accumulation process, which affect the flavor quality of oriental melon fruit.
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Affiliation(s)
- Cheng Wang
- College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China; Key Laboratory of Protected Horticulture of Education of Ministry and Liaoning Province, China; National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang, 110866, China
| | - Hongchao Jiang
- College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China; Key Laboratory of Protected Horticulture of Education of Ministry and Liaoning Province, China; National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang, 110866, China
| | - Ge Gao
- College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China; Key Laboratory of Protected Horticulture of Education of Ministry and Liaoning Province, China; National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang, 110866, China
| | - Fan Yang
- College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China; Key Laboratory of Protected Horticulture of Education of Ministry and Liaoning Province, China; National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang, 110866, China
| | - Jingyue Guan
- College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China; Key Laboratory of Protected Horticulture of Education of Ministry and Liaoning Province, China; National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang, 110866, China
| | - Hongyan Qi
- College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China; Key Laboratory of Protected Horticulture of Education of Ministry and Liaoning Province, China; National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang, 110866, China.
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3
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Kang J, Gong J, Zhang L, Gao Z, Xie Q, Hu Z, Chen G. A novel E6-like gene, E6-2, affects fruit ripening in tomato. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 313:111066. [PMID: 34763858 DOI: 10.1016/j.plantsci.2021.111066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 09/07/2021] [Accepted: 09/22/2021] [Indexed: 06/13/2023]
Abstract
Tomato fruit ripening is a complicated and well-coordinated process with numerous metabolic changes resulted from endogenous hormone and genetic regulators. Although the regulation of MADS-box transcription factor (MADS-RIN) controlling fruit ripening has been widely reported, its mechanisms underlying need to be further improved. Here, we characterized a novel tomato E6-like gene, E6-2, whose transcripts showed a high accumulation in fruit ripening stages (Breaker, Breaker+4 and Breaker+7), but a low level was observed in Never ripe (Nr) and ripening inhibitor (rin) mutants. MADS-RIN directly activates the expression of E6-2 in vivo. Additionally, a remarkable reduction of E6-2 was observed in wild-type (WT) tomato fruits at the MG stage treated with 1-MCP. RNAi-mediated silencing of E6-2 resulted in delayed fruit ripening, reduced accumulation of the total carotenoid and lycopene, reduced content of ethylene production, and increased contents of the total pectin, cellulose, starch and soluble sugar. Moreover, the expression of carotenoid biosynthesis genes (PSY1, PDS and ZDS), ripening-related genes (CNR, PG and ERF4), ethylene biosynthesis genes (ACS2, ACO1 and ACO3), ethylene-responsive genes (E4 and E8) and cell wall metabolism genes (TBG4, PL, EXP1 and XTH5) were inhibited in E6-2 -RNAi lines. These results indicate that E6-2 plays an important role in regulating tomato fruit ripening targeted by RIN.
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Affiliation(s)
- Jing Kang
- Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, People's Republic of China.
| | - Jun Gong
- Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, People's Republic of China.
| | - Lincheng Zhang
- Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, People's Republic of China.
| | - Zihan Gao
- Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, People's Republic of China.
| | - Qiaoli Xie
- Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, People's Republic of China.
| | - Zongli Hu
- Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, People's Republic of China.
| | - Guoping Chen
- Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, People's Republic of China.
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Ernesto Bianchetti R, Silvestre Lira B, Santos Monteiro S, Demarco D, Purgatto E, Rothan C, Rossi M, Freschi L. Fruit-localized phytochromes regulate plastid biogenesis, starch synthesis, and carotenoid metabolism in tomato. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:3573-3586. [PMID: 29912373 PMCID: PMC6022544 DOI: 10.1093/jxb/ery145] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 04/10/2018] [Indexed: 05/05/2023]
Abstract
Light signaling has long been reported to influence fruit biology, although the regulatory impact of fruit-localized photoreceptors on fruit development and metabolism remains unclear. Studies performed in phytochrome (PHY)-deficient tomato (Solanum lycopersicum) mutants suggest that SlPHYA, SlPHYB2, and to a lesser extent SlPHYB1 influence fruit development and ripening. By employing fruit-specific RNAi-mediated silencing of SlPHY genes, we demonstrated that fruit-localized SlPHYA and SlPHYB2 play contrasting roles in regulating plastid biogenesis and maturation in tomato. Our data revealed that fruit-localized SlPHYA, rather than SlPHYB1 or SlPHYB2, positively influences tomato plastid differentiation and division machinery via changes in both light and cytokinin signaling-related gene expression. Fruit-localized SlPHYA and SlPHYB2 were also shown to modulate sugar metabolism in early developing fruits via overlapping, yet distinct, mechanisms involving the co-ordinated transcriptional regulation of genes related to sink strength and starch biosynthesis. Fruit-specific SlPHY silencing also drastically altered the transcriptional profile of genes encoding light-repressor proteins and carotenoid-biosynthesis regulators, leading to reduced carotenoid biosynthesis during fruit ripening. Together, our data reveal the existence of an intricate PHY-hormonal interplay during fruit development and ripening, and provide conclusive evidence on the regulation of tomato quality by fruit-localized phytochromes.
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Affiliation(s)
- Ricardo Ernesto Bianchetti
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, São Paulo, Brazil
| | - Bruno Silvestre Lira
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, São Paulo, Brazil
| | - Scarlet Santos Monteiro
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, São Paulo, Brazil
| | - Diego Demarco
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, São Paulo, Brazil
| | - Eduardo Purgatto
- Departamento de Alimentos e Nutrição Experimental, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Professor Lineu Prestes, São Paulo, Brazil
| | - Christophe Rothan
- INRA, Université de Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, Villenave d’Ornon, France
| | - Magdalena Rossi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, São Paulo, Brazil
| | - Luciano Freschi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, São Paulo, Brazil
- Correspondence:
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Seferoglu AB, Gul S, Dikbas UM, Baris I, Koper K, Caliskan M, Cevahir G, Kavakli IH. Glu-370 in the large subunit influences the substrate binding, allosteric, and heat stability properties of potato ADP-glucose pyrophosphorylase. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 252:125-132. [PMID: 27717448 DOI: 10.1016/j.plantsci.2016.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 07/12/2016] [Accepted: 07/13/2016] [Indexed: 06/06/2023]
Abstract
ADP-glucose pyrophosphorylase (AGPase) is a key allosteric enzyme in plant starch biosynthesis. Plant AGPase is a heterotetrameric enzyme that consists of large (LS) and small subunits (SS), which are encoded by two different genes. In this study, we showed that the conversion of Glu to Gly at position 370 in the LS of AGPase alters the heterotetrameric stability along with the binding properties of substrate and effectors of the enzyme. Kinetic analyses revealed that the affinity of the LSE370GSSWT AGPase for glucose-1-phosphate is 3-fold less than for wild type (WT) AGPase. Additionally, the LSE370GSSWT AGPase requires 3-fold more 3-phosphogyceric acid to be activated. Finally, the LSE370GSSWTAGPase is less heat stable compared with the WT AGPase. Computational analysis of the mutant Gly-370 in the 3D modeled LS AGPase showed that this residue changes charge distribution of the surface and thus affect stability of the LS AGPase and overall heat stability of the heterotetrameric AGPase. In summary, our results show that LSE370 intricately modulate the heat stability and enzymatic activity of potato the AGPase.
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Affiliation(s)
- Ayse Bengisu Seferoglu
- Koc University, Department of Chemical and Biological Engineering, Rumelifeneri Yolu, Sariyer, Istanbul, Turkey
| | - Seref Gul
- Koc University, Department of Chemical and Biological Engineering, Rumelifeneri Yolu, Sariyer, Istanbul, Turkey
| | - Ugur Meric Dikbas
- Koc University, Department of Molecular Biology and Genetics, Rumelifeneri Yolu, Sariyer, Istanbul, Turkey
| | - Ibrahim Baris
- Koc University, Department of Molecular Biology and Genetics, Rumelifeneri Yolu, Sariyer, Istanbul, Turkey
| | - Kaan Koper
- Koc University, Department of Chemical and Biological Engineering, Rumelifeneri Yolu, Sariyer, Istanbul, Turkey
| | - Mahmut Caliskan
- Istanbul University, Department of Biology, 34134 Suleymaniye, Istanbul, Turkey
| | - Gul Cevahir
- Istanbul University, Department of Biology, 34134 Suleymaniye, Istanbul, Turkey
| | - Ibrahim Halil Kavakli
- Koc University, Department of Chemical and Biological Engineering, Rumelifeneri Yolu, Sariyer, Istanbul, Turkey; Koc University, Department of Molecular Biology and Genetics, Rumelifeneri Yolu, Sariyer, Istanbul, Turkey.
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6
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Tang XJ, Peng C, Zhang J, Cai Y, You XM, Kong F, Yan HG, Wang GX, Wang L, Jin J, Chen WW, Chen XG, Ma J, Wang P, Jiang L, Zhang WW, Wan JM. ADP-glucose pyrophosphorylase large subunit 2 is essential for storage substance accumulation and subunit interactions in rice endosperm. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 249:70-83. [PMID: 27297991 DOI: 10.1016/j.plantsci.2016.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/04/2016] [Accepted: 05/13/2016] [Indexed: 05/26/2023]
Abstract
ADP-glucose pyrophosphorylase (AGPase) controls a rate-limiting step in the starch biosynthetic pathway in higher plants. Here we isolated a shrunken rice mutant w24. Map-based cloning identified OsAGPL2, a large subunit of the cytosolic AGPase in rice endosperm, as the gene responsible for the w24 mutation. In addition to severe inhibition of starch synthesis and significant accumulation of sugar, the w24 endosperm showed obvious defects in compound granule formation and storage protein synthesis. The defect in OsAGPL2 enhanced the expression levels of the AGPase family. Meanwhile, the elevated activities of starch phosphorylase 1 and sucrose synthase in the w24 endosperm might possibly partly account for the residual starch content in the mutant seeds. Moreover, the expression of OsAGPL2 and its counterpart, OsAGPS2b, was highly coordinated in rice endosperm. Yeast two-hybrid and BiFC assays verified direct interactions between OsAGPL2 and OsAGPS2b as well as OsAGPL1 and OsAGPS1, supporting the model for spatiotemporal complex formation of AGPase isoforms in rice endosperm. Besides, our data provided no evidence for the self-binding of OsAGPS2b, implying that OsAGPS2b might not interact to form higher molecular mass aggregates in the absence of OsAGPL2. Therefore, the molecular mechanism of rice AGPase assembly might differ from that of Arabidopsis.
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Affiliation(s)
- Xiao-Jie Tang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Cheng Peng
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Jie Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Yue Cai
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Xiao-Man You
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Fei Kong
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Hai-Gang Yan
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Guo-Xiang Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Liang Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Jie Jin
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Wei-Wei Chen
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Xin-Gang Chen
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Jing Ma
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Peng Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Ling Jiang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Wen-Wei Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
| | - Jian-Min Wan
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China; Institute of Crop Science, The National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 Zhongguancun South Street, Beijing 100081, China.
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Saripalli G, Gupta PK. AGPase: its role in crop productivity with emphasis on heat tolerance in cereals. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2015; 128:1893-916. [PMID: 26152573 DOI: 10.1007/s00122-015-2565-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 06/16/2015] [Indexed: 05/11/2023]
Abstract
AGPase, a key enzyme of starch biosynthetic pathway, has a significant role in crop productivity. Thermotolerant variants of AGPase in cereals may be used for developing cultivars, which may enhance productivity under heat stress. Improvement of crop productivity has always been the major goal of plant breeders to meet the global demand for food. However, crop productivity itself is influenced in a large measure by a number of abiotic stresses including heat, which causes major losses in crop productivity. In cereals, crop productivity in terms of grain yield mainly depends upon the seed starch content so that starch biosynthesis and the enzymes involved in this process have been a major area of investigation for plant physiologists and plant breeders alike. Considerable work has been done on AGPase and its role in crop productivity, particularly under heat stress, because this enzyme is one of the major enzymes, which catalyses the rate-limiting first committed key enzymatic step of starch biosynthesis. Keeping the above in view, this review focuses on the basic features of AGPase including its structure, regulatory mechanisms involving allosteric regulators, its sub-cellular localization and its genetics. Major emphasis, however, has been laid on the genetics of AGPases and its manipulation for developing high yielding cultivars that will have comparable productivity under heat stress. Some important thermotolerant variants of AGPase, which mainly involve specific amino acid substitutions, have been highlighted, and the prospects of using these thermotolerant variants of AGPase in developing cultivars for heat prone areas have been discussed. The review also includes a brief account on transgenics for AGPase, which have been developed for basic studies and crop improvement.
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Affiliation(s)
- Gautam Saripalli
- Molecular Biology Laboratory, Department of Genetics and Plant Breeding, Ch.Charan Singh University, Meerut, 250004, India
| | - Pushpendra Kumar Gupta
- Molecular Biology Laboratory, Department of Genetics and Plant Breeding, Ch.Charan Singh University, Meerut, 250004, India.
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Structural comparison, substrate specificity, and inhibitor binding of AGPase small subunit from monocot and dicot: present insight and future potential. BIOMED RESEARCH INTERNATIONAL 2014; 2014:583606. [PMID: 25276800 PMCID: PMC4167649 DOI: 10.1155/2014/583606] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/08/2014] [Accepted: 04/21/2014] [Indexed: 11/18/2022]
Abstract
ADP-glucose pyrophosphorylase (AGPase) is the first rate limiting enzyme of starch biosynthesis pathway and has been exploited as the target for greater starch yield in several plants. The structure-function analysis and substrate binding specificity of AGPase have provided enormous potential for understanding the role of specific amino acid or motifs responsible for allosteric regulation and catalytic mechanisms, which facilitate the engineering of AGPases. We report the three-dimensional structure, substrate, and inhibitor binding specificity of AGPase small subunit from different monocot and dicot crop plants. Both monocot and dicot subunits were found to exploit similar interactions with the substrate and inhibitor molecule as in the case of their closest homologue potato tuber AGPase small subunit. Comparative sequence and structural analysis followed by molecular docking and electrostatic surface potential analysis reveal that rearrangements of secondary structure elements, substrate, and inhibitor binding residues are strongly conserved and follow common folding pattern and orientation within monocot and dicot displaying a similar mode of allosteric regulation and catalytic mechanism. The results from this study along with site-directed mutagenesis complemented by molecular dynamics simulation will shed more light on increasing the starch content of crop plants to ensure the food security worldwide.
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Seferoglu AB, Koper K, Can FB, Cevahir G, Kavakli IH. Enhanced heterotetrameric assembly of potato ADP-glucose pyrophosphorylase using reverse genetics. PLANT & CELL PHYSIOLOGY 2014; 55:1473-1483. [PMID: 24891561 DOI: 10.1093/pcp/pcu078] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
ADP-glucose pyrophosphorylase (AGPase) is a key allosteric enzyme in plant starch biosynthesis. Plant AGPase is a heterotetrameric enzyme that consists of large (LS) and small subunits (SS), which are encoded by two different genes. Computational and experimental studies have revealed that the heterotetrameric assembly of AGPase is thermodynamically weak. Modeling studies followed by the mutagenesis of the LS of the potato AGPase identified a heterotetramer-deficient mutant, LS(R88A). To enhance heterotetrameric assembly, LS(R88A) cDNA was subjected to error-prone PCR, and second-site revertants were identified according to their ability to restore glycogen accumulation, as assessed with iodine staining. Selected mutations were introduced into the wild-type (WT) LS and co-expressed with the WT SS in Escherichia coli glgC(-). The biochemical characterization of revertants revealed that LS(I90V)SS(WT), LS(Y378C)SS(WT) and LS(D410G)SS(WT) mutants displayed enhanced heterotetrameric assembly with the WT SS. Among these mutants, LS(Y378C)SS(WT) AGPase displayed increased heat stability compared with the WT enzyme. Kinetic characterization of the mutants indicated that the LS(I90V)SS(WT) and LS(Y378C)SS(WT) AGPases have comparable allosteric and kinetic properties. However, the LS(D410G)SS(WT) mutant exhibited altered allosteric properties of being less responsive and more sensitive to 3-phosphoglyceric acid activation and inorganic phosphate inhibition. This study not only enhances our understanding of the interaction between the SS and the LS of AGPase but also enables protein engineering to obtain enhanced assembled heat-stable variants of AGPase, which can be used for the improvement of plant yields.
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Affiliation(s)
- A Bengisu Seferoglu
- Department of Chemical and Biological Engineering, Koc University, Rumeli Feneri Yolu, 34450 Sariyer, Turkey
| | - Kaan Koper
- Department of Chemical and Biological Engineering, Koc University, Rumeli Feneri Yolu, 34450 Sariyer, Turkey
| | - F Betul Can
- Department of Molecular Biology and Genetics, Koc University, Rumeli Feneri Yolu, 34450 Sariyer, Turkey
| | - Gul Cevahir
- Istanbul University, Department of Biology, 34134 Suleymaniye, Istanbul, Turkey
| | - I Halil Kavakli
- Department of Chemical and Biological Engineering, Koc University, Rumeli Feneri Yolu, 34450 Sariyer, TurkeyDepartment of Molecular Biology and Genetics, Koc University, Rumeli Feneri Yolu, 34450 Sariyer, Turkey
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Tuncel A, Kawaguchi J, Ihara Y, Matsusaka H, Nishi A, Nakamura T, Kuhara S, Hirakawa H, Nakamura Y, Cakir B, Nagamine A, Okita TW, Hwang SK, Satoh H. The rice endosperm ADP-glucose pyrophosphorylase large subunit is essential for optimal catalysis and allosteric regulation of the heterotetrameric enzyme. PLANT & CELL PHYSIOLOGY 2014; 55:1169-83. [PMID: 24747952 DOI: 10.1093/pcp/pcu057] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Although an alternative pathway has been suggested, the prevailing view is that starch synthesis in cereal endosperm is controlled by the activity of the cytosolic isoform of ADPglucose pyrophosphorylase (AGPase). In rice, the cytosolic AGPase isoform is encoded by the OsAGPS2b and OsAGPL2 genes, which code for the small (S2b) and large (L2) subunits of the heterotetrameric enzyme, respectively. In this study, we isolated several allelic missense and nonsense OsAGPL2 mutants by N-methyl-N-nitrosourea (MNU) treatment of fertilized egg cells and by TILLING (Targeting Induced Local Lesions in Genomes). Interestingly, seeds from three of the missense mutants (two containing T139I and A171V) were severely shriveled and had seed weight and starch content comparable with the shriveled seeds from OsAGPL2 null mutants. Results from kinetic analysis of the purified recombinant enzymes revealed that the catalytic and allosteric regulatory properties of these mutant enzymes were significantly impaired. The missense heterotetramer enzymes and the S2b homotetramer had lower specific (catalytic) activities and affinities for the activator 3-phosphoglycerate (3-PGA). The missense heterotetramer enzymes showed more sensitivity to inhibition by the inhibitor inorganic phosphate (Pi) than the wild-type AGPase, while the S2b homotetramer was profoundly tolerant to Pi inhibition. Thus, our results provide definitive evidence that starch biosynthesis during rice endosperm development is controlled predominantly by the catalytic activity of the cytoplasmic AGPase and its allosteric regulation by the effectors. Moreover, our results show that the L2 subunit is essential for both catalysis and allosteric regulatory properties of the heterotetramer enzyme.
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Affiliation(s)
- Aytug Tuncel
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USAThese authors contributed equally to this work
| | - Joe Kawaguchi
- Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 JapanThese authors contributed equally to this work
| | - Yasuharu Ihara
- Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan
| | | | - Aiko Nishi
- Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan
| | | | - Satoru Kuhara
- Department of Genetic Resources Technology, Kyushu University, Fukuoka, 812-8581 Japan
| | - Hideki Hirakawa
- Kazusa DNA Research Institute, Department of Plant Genome Research, Kisarazu, Japan
| | - Yasunori Nakamura
- Faculty of Bioresource Sciences, Akita Prefectural University, Akita City, 010-0195 Japan
| | - Bilal Cakir
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USA
| | - Ai Nagamine
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USAFaculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan
| | - Thomas W Okita
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USA
| | - Seon-Kap Hwang
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USA
| | - Hikaru Satoh
- Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan
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Tuncel A, Okita TW. Improving starch yield in cereals by over-expression of ADPglucose pyrophosphorylase: expectations and unanticipated outcomes. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 211:52-60. [PMID: 23987811 DOI: 10.1016/j.plantsci.2013.06.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Revised: 06/13/2013] [Accepted: 06/17/2013] [Indexed: 05/09/2023]
Abstract
Significant improvements in crop productivity are required to meet the nutritional requirements of a growing world population. This challenge is magnified by an increased demand for bioenergy as a means to mitigate carbon inputs into the environment. Starch is a major component of the harvestable organs of many crop plants, and various endeavors have been taken to improve the yields of starchy organs through the manipulation of starch synthesis. Substantial efforts have centered on the starch regulatory enzyme ADPglucose pyrophosphorylase (AGPase) due to its pivotal role in starch biosynthesis. These efforts include over-expression of this enzyme in cereal plants such as maize, rice and wheat as well as potato and cassava, as they supply the bulk of the staple food worldwide. In this perspective, we describe efforts to increase starch yields in cereal grains by first providing an introduction about the importance of source-sink relationship and the motives behind the efforts to alter starch biosynthesis and turnover in leaves. We then discuss the catalytic and regulatory properties of AGPase and the molecular approaches used to enhance starch synthesis by manipulation of this process during grain filling using seed-specific promoters. Several studies have demonstrated increases in starch content per seed using endosperm-specific promoters, but other studies have demonstrated an increase in seed number with only marginal impact on seed weight. Potential mechanisms that may be responsible for this paradoxical increase in seed number will also be discussed. Finally, we describe current efforts and future prospects to improve starch yield in cereals. These efforts include further enhancement of starch yield in rice by augmenting the process of ADPglucose transport into amyloplast as well as other enzymes involved in photoassimilate partitioning in seeds.
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Affiliation(s)
- Aytug Tuncel
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, United States
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Corbi J, Dutheil JY, Damerval C, Tenaillon MI, Manicacci D. Accelerated evolution and coevolution drove the evolutionary history of AGPase sub-units during angiosperm radiation. ANNALS OF BOTANY 2012; 109:693-708. [PMID: 22307567 PMCID: PMC3286274 DOI: 10.1093/aob/mcr303] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 11/07/2011] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS ADP-glucose pyrophosphorylase (AGPase) is a key enzyme of starch biosynthesis. In the green plant lineage, it is composed of two large (LSU) and two small (SSU) sub-units encoded by paralogous genes, as a consequence of several rounds of duplication. First, our aim was to detect specific patterns of molecular evolution following duplication events and the divergence between monocotyledons and dicotyledons. Secondly, we investigated coevolution between amino acids both within and between sub-units. METHODS A phylogeny of each AGPase sub-unit was built using all gymnosperm and angiosperm sequences available in databases. Accelerated evolution along specific branches was tested using the ratio of the non-synonymous to the synonymous substitution rate. Coevolution between amino acids was investigated taking into account compensatory changes between co-substitutions. KEY RESULTS We showed that SSU paralogues evolved under high functional constraints during angiosperm radiation, with a significant level of coevolution between amino acids that participate in SSU major functions. In contrast, in the LSU paralogues, we identified residues under positive selection (1) following the first LSU duplication that gave rise to two paralogues mainly expressed in angiosperm source and sink tissues, respectively; and (2) following the emergence of grass-specific paralogues expressed in the endosperm. Finally, we found coevolution between residues that belong to the interaction domains of both sub-units. CONCLUSIONS Our results support the view that coevolution among amino acid residues, especially those lying in the interaction domain of each sub-unit, played an important role in AGPase evolution. First, within SSU, coevolution allowed compensating mutations in a highly constrained context. Secondly, the LSU paralogues probably acquired tissue-specific expression and regulatory properties via the coevolution between sub-unit interacting domains. Finally, the pattern we observed during LSU evolution is consistent with repeated sub-functionalization under 'Escape from Adaptive Conflict', a model rarely illustrated in the literature.
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Affiliation(s)
- Jonathan Corbi
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, Ferme du Moulon, F-91190 Gif sur Yvette, France
| | - Julien Y. Dutheil
- BiRC-Bioinformatics Research Center, Aarhus University, C.F. Møllers Alle 8, Building 1110, DK-8000 Århus C, Denmark
| | - Catherine Damerval
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, Ferme du Moulon, F-91190 Gif sur Yvette, France
| | - Maud I. Tenaillon
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, Ferme du Moulon, F-91190 Gif sur Yvette, France
| | - Domenica Manicacci
- Université Paris-Sud, UMR 0320/UMR 8120 Génétique Végétale, Ferme du Moulon, F-91190 Gif sur Yvette, France
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Corbi J, Debieu M, Rousselet A, Montalent P, Le Guilloux M, Manicacci D, Tenaillon MI. Contrasted patterns of selection since maize domestication on duplicated genes encoding a starch pathway enzyme. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2011; 122:705-22. [PMID: 21060986 DOI: 10.1007/s00122-010-1480-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 10/22/2010] [Indexed: 05/08/2023]
Abstract
Maize domestication from teosinte (Zea mays ssp. parviglumis) was accompanied by an increase of kernel size in landraces. Subsequent breeding has led to a diversification of kernel size and starch content among major groups of inbred lines. We aim at investigating the effect of domestication on duplicated genes encoding a key enzyme of the starch pathway, the ADP-glucose pyrophosphorylase (AGPase). Three pairs of paralogs encode the AGPase small (SSU) and large (LSU) subunits mainly expressed in the endosperm, the embryo and the leaf. We first validated the putative sequence of LSU(leaf) through a comparative expression assay of the six genes. Second, we investigated the patterns of molecular evolution on a 2 kb coding region homologous among the six genes in three panels: teosintes, landraces, and inbred lines. We corrected for demographic effects by relying on empirical distributions built from 580 previously sequenced ESTs. We found contrasted patterns of selection among duplicates: three genes exhibit patterns of directional selection during domestication (SSU(end), LSU(emb)) or breeding (LSU(leaf)), two exhibit patterns consistent with diversifying (SSU(leaf)) and balancing selection (SSU(emb)) accompanying maize breeding. While patterns of linkage disequilibrium did not reveal sign of coevolution between genes expressed in the same organ, we detected an excess of non-synonymous substitutions in the small subunit functional domains highlighting their role in AGPase evolution. Our results offer a different picture on AGPase evolution than the one depicted at the Angiosperm level and reveal how genetic redundancy can provide flexibility in the response to selection.
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Affiliation(s)
- J Corbi
- CNRS, UMR 0320/UMR 8120 Génétique Végétale, Ferme du Moulon, Gif sur Yvette, France
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Georgelis N, Shaw JR, Hannah LC. Phylogenetic analysis of ADP-glucose pyrophosphorylase subunits reveals a role of subunit interfaces in the allosteric properties of the enzyme. PLANT PHYSIOLOGY 2009; 151:67-77. [PMID: 19625637 PMCID: PMC2735977 DOI: 10.1104/pp.109.138933] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
ADP-glucose pyrophosphorylase (AGPase) catalyzes a rate-limiting step in glycogen and starch synthesis in bacteria and plants, respectively. Plant AGPase consists of two large and two small subunits that were derived by gene duplication. AGPase large subunits have functionally diverged, leading to different kinetic and allosteric properties. Amino acid changes that could account for these differences were identified previously by evolutionary analysis. In this study, these large subunit residues were mapped onto a modeled structure of the maize (Zea mays) endosperm enzyme. Surprisingly, of 29 amino acids identified via evolutionary considerations, 17 were located at subunit interfaces. Fourteen of the 29 amino acids were mutagenized in the maize endosperm large subunit (SHRUNKEN-2 [SH2]), and resulting variants were expressed in Escherichia coli with the maize endosperm small subunit (BT2). Comparisons of the amount of glycogen produced in E. coli, and the kinetic and allosteric properties of the variants with wild-type SH2/BT2, indicate that 11 variants differ from the wild type in enzyme properties or in vivo glycogen level. More interestingly, six of nine residues located at subunit interfaces exhibit altered allosteric properties. These results indicate that the interfaces between the large and small subunits are important for the allosteric properties of AGPase, and changes at these interfaces contribute to AGPase functional specialization. Our results also demonstrate that evolutionary analysis can greatly facilitate enzyme structure-function analyses.
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Affiliation(s)
- Nikolaos Georgelis
- Program in Plant Molecular and Cellular Biology and Horticultural Sciences, University of Florida, Gainesville, Florida 32610-0245, USA
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