Elucidating paramylon and other carbohydrate metabolism in Euglena gracilis: Kinetic characterization, structure and cellular localization of UDP-glucose pyrophosphorylase

Muchut, Robertino J.; Calloni, Rodrigo D.; Herrera, Fernando E.; Garay, Sergio; Arias, Diego Gustavo; Iglesias, Alberto A.; Guerrero, Sandra

doi:10.1016/j.biochi.2018.09.006

Cited by 9 publications

(7 citation statements)

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“…Such a pairing of cysteines is rather unlikely for plant UGPases, due to a large distance between cysteines in crystallized Arabidopsis UGPase (McCoy et al., 2007). Recently, Euglena UGPase was also found to be redox regulated, with oxidation by hydrogen peroxide inactivating the enzyme, which could be reversed by reduction of dithiothreitol or thioredoxin (Muchut et al., 2018). The inactivation was explained by the formation of sulfenic acid derivatives by oxidized cysteines, possibly leading to a change of conformation of the protein.…”

Section: Ugpase Enzymementioning

confidence: 99%

UDP-Sugar Producing Pyrophosphorylases: Distinct and Essential Enzymes With Overlapping Substrate Specificities, Providing de novo Precursors for Glycosylation Reactions

Decker

Kleczkowski

2019

Front. Plant Sci.

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Nucleotide sugars are the key precursors for all glycosylation reactions and are required both for oligo- and polysaccharides synthesis and protein and lipid glycosylation. Among all nucleotide sugars, UDP-sugars are the most important precursors for biomass production in nature (e.g., synthesis of cellulose, hemicellulose, and pectins for cell wall production). Several recent studies have already suggested a potential role for UDP-Glc in plant growth and development, and UDP-Glc has also been suggested as a signaling molecule, in addition to its precursor function. In this review, we will cover primary mechanisms of formation of UDP-sugars, by focusing on UDP-sugar metabolizing pyrophosphorylases. The pyrophosphorylases can be divided into three families: UDP-Glc pyrophosphorylase (UGPase), UDP-sugar pyrophosphorylase (USPase), and UDP-N-acetyl glucosamine pyrophosphorylase (UAGPase), which can be distinguished both by their amino acid sequences and by differences in substrate specificity. Substrate specificities of these enzymes are discussed, along with structure-function relationships, based on their crystal structures and homology modeling. Earlier studies with transgenic plants have revealed that each of the pyrophosphorylases is essential for plant survival, and their loss or a decrease in activity results in reproductive impairment. This constitutes a problem when studying exact in vivo roles of the enzymes using classical reverse genetics approaches. Thus, strategies involving the use of specific inhibitors (reverse chemical genetics) are also discussed. Further characterization of the properties/roles of pyrophosphorylases should address fundamental questions dealing with mechanisms and control of carbohydrate synthesis and may allow to identify targets for manipulation of biomass production in plants.

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Section: Ugpase Enzymementioning

confidence: 99%

UDP-Sugar Producing Pyrophosphorylases: Distinct and Essential Enzymes With Overlapping Substrate Specificities, Providing de novo Precursors for Glycosylation Reactions

Decker

Kleczkowski

2019

Front. Plant Sci.

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“…Surprisingly, however, no focused studies were carried out on possible redox modulation of the higher plant enzyme, a process known to affect hundreds of proteins [18,19]. Earlier studies on simple single-celled eukaryotes have revealed that UGPase activity is modulated by a redox mechanism involving oxidation and reduction of specific cysteine (Cys) residues [12,20,21]. For plant UGPases, the first hints of its possible redox control came from high-throughput proteomics studies [22,23], where seed UGPase was identified as one of many targets for in vivo interaction with thioredoxins, small proteins mediating redox control during oxidative stress conditions [24].…”

Section: Introductionmentioning

confidence: 99%

Exploring Redox Modulation of Plant UDP-Glucose Pyrophosphorylase

Decker

Aubert

Wilczyńska

et al. 2023

IJMS

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UDP-glucose (UDPG) pyrophosphorylase (UGPase) catalyzes a reversible reaction, producing UDPG, which serves as an essential precursor for hundreds of glycosyltransferases in all organisms. In this study, activities of purified UGPases from sugarcane and barley were found to be reversibly redox modulated in vitro through oxidation by hydrogen peroxide or oxidized glutathione (GSSG) and through reduction by dithiothreitol or glutathione. Generally, while oxidative treatment decreased UGPase activity, a subsequent reduction restored the activity. The oxidized enzyme had increased Km values with substrates, especially pyrophosphate. The increased Km values were also observed, regardless of redox status, for UGPase cysteine mutants (Cys102Ser and Cys99Ser for sugarcane and barley UGPases, respectively). However, activities and substrate affinities (Kms) of sugarcane Cys102Ser mutant, but not barley Cys99Ser, were still prone to redox modulation. The data suggest that plant UGPase is subject to redox control primarily via changes in the redox status of a single cysteine. Other cysteines may also, to some extent, contribute to UGPase redox status, as seen for sugarcane enzymes. The results are discussed with respect to earlier reported details of redox modulation of eukaryotic UGPases and regarding the structure/function properties of these proteins.

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“…The β-glucan content in yeast has been found to be less than 15% of its dry weight and is intracellular which makes its isolation an energy intensive process due to presence of tough cell wall ( Zhu et al., 2016 ). E. gracilis can accumulate large quantities of β-1,3-glucan in the range of 20–75% of dry weight when cultivated in the presence of adequate carbon sources ( Muchut et al., 2018 ). E. gracilis is devoid of cell wall and therefore β-1,3-glucan extraction is much easier as compared to that of S. cerevisiae .…”

Section: Introductionmentioning

confidence: 99%

Prebiotic activity of paramylon isolated from heterotrophically grown Euglena gracilis

Bhattad¹,

Koradiya

Prakash³

2021

Heliyon

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show abstract

Elucidating paramylon and other carbohydrate metabolism in Euglena gracilis: Kinetic characterization, structure and cellular localization of UDP-glucose pyrophosphorylase

Cited by 9 publications

References 50 publications

UDP-Sugar Producing Pyrophosphorylases: Distinct and Essential Enzymes With Overlapping Substrate Specificities, Providing de novo Precursors for Glycosylation Reactions

UDP-Sugar Producing Pyrophosphorylases: Distinct and Essential Enzymes With Overlapping Substrate Specificities, Providing de novo Precursors for Glycosylation Reactions

Exploring Redox Modulation of Plant UDP-Glucose Pyrophosphorylase

Prebiotic activity of paramylon isolated from heterotrophically grown Euglena gracilis

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