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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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Kang X, Gao W, Cui B, El-Aty AMA. Structure and genetic regulation of starch formation in sorghum (Sorghum bicolor (L.) Moench) endosperm: A review. Int J Biol Macromol 2023; 239:124315. [PMID: 37023877 DOI: 10.1016/j.ijbiomac.2023.124315] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 03/27/2023] [Accepted: 03/30/2023] [Indexed: 04/08/2023]
Abstract
This review focuses on the structure and genetic regulation of starch formation in sorghum (Sorghum bicolor (L.) Moench) endosperm. Sorghum is an important cereal crop that is well suited to grow in regions with high temperatures and limited water resources due to its C4 metabolism. The endosperm of sorghum kernels is a rich source of starch, which is composed of two main components: amylose and amylopectin. The synthesis of starch in sorghum endosperm involves multiple enzymatic reactions, which are regulated by complex genetic and environmental factors. Recent research has identified several genes involved in the regulation of starch synthesis in sorghum endosperm. In addition, the structure and properties of sorghum starch can also be influenced by environmental factors such as temperature, water availability, and soil nutrients. A better understanding of the structure and genetic regulation of starch formation in sorghum endosperm can have important implications for the development of sorghum-based products with improved quality and nutritional value. This review provides a comprehensive summary of the current knowledge on the structure and genetic regulation of starch formation in sorghum endosperm and highlights the potential for future research to further improve our understanding of this important process.
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Affiliation(s)
- Xuemin Kang
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China; School of Food Science and Engineering, Qilu University of Technology, Shandong Academy of Sciences, Jinan, Shandong 250353, China; Department of Food Science and Engineering, Shandong Agricultural University, Taian 271018, China
| | - Wei Gao
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China; School of Food Science and Engineering, Qilu University of Technology, Shandong Academy of Sciences, Jinan, Shandong 250353, China
| | - Bo Cui
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China; School of Food Science and Engineering, Qilu University of Technology, Shandong Academy of Sciences, Jinan, Shandong 250353, China; Department of Food Science and Engineering, Shandong Agricultural University, Taian 271018, China.
| | - A M Abd El-Aty
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China; Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, 12211 Giza, Egypt; Department of Medical Pharmacology, Medical Faculty, Ataturk University, 25240 Erzurum, Turkey
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Figueroa CM, Asencion Diez MD, Ballicora MA, Iglesias AA. Structure, function, and evolution of plant ADP-glucose pyrophosphorylase. PLANT MOLECULAR BIOLOGY 2022; 108:307-323. [PMID: 35006475 DOI: 10.1007/s11103-021-01235-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 12/15/2021] [Indexed: 05/25/2023]
Abstract
This review outlines research performed in the last two decades on the structural, kinetic, regulatory and evolutionary aspects of ADP-glucose pyrophosphorylase, the regulatory enzyme for starch biosynthesis. ADP-glucose pyrophosphorylase (ADP-Glc PPase) catalyzes the first committed step in the pathway of glycogen and starch synthesis in bacteria and plants, respectively. Plant ADP-Glc PPase is a heterotetramer allosterically regulated by metabolites and post-translational modifications. In this review, we focus on the three-dimensional structure of the plant enzyme, the amino acids that bind the regulatory molecules, and the regions involved in transmitting the allosteric signal to the catalytic site. We provide a model for the evolution of the small and large subunits, which produce heterotetramers with distinct catalytic and regulatory properties. Additionally, we review the various post-translational modifications observed in ADP-Glc PPases from different species and tissues. Finally, we discuss the subcellular localization of the enzyme found in grain endosperm from grasses, such as maize and rice. Overall, this work brings together research performed in the last two decades to better understand the multiple mechanisms involved in the regulation of ADP-Glc PPase. The rational modification of this enzyme could improve the yield and resilience of economically important crops, which is particularly important in the current scenario of climate change and food shortage.
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Affiliation(s)
- Carlos M Figueroa
- Instituto de Agrobiotecnología del Litoral, Universidad Nacional del Litoral, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Bioquímica y Ciencias Biológicas, Santa Fe, Argentina
| | - Matías D Asencion Diez
- Instituto de Agrobiotecnología del Litoral, Universidad Nacional del Litoral, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Bioquímica y Ciencias Biológicas, Santa Fe, Argentina
| | - Miguel A Ballicora
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, USA.
| | - Alberto A Iglesias
- Instituto de Agrobiotecnología del Litoral, Universidad Nacional del Litoral, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Bioquímica y Ciencias Biológicas, Santa Fe, Argentina.
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