Glycogen as a carbohydrate energy reserve in trophozoites of Giardia lamblia

Ladeira, Rodolfo Braga; Freitas, Michelle A. R.; Silva, Edward F.; Gontijo, Nelder F.; Gomes, Maria Aparecida

doi:10.1007/s00436-005-1356-0

Cited by 9 publications

(6 citation statements)

References 15 publications

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“…Combining this result with previous reports that glycogen has been found to be present in trophozoites [22], we suggest that Giardia is able to generate glycogen from glucose to serve as an energy reserve.…”

Section: Resultssupporting

confidence: 88%

Reconstruction of Sugar Metabolic Pathways of Giardia lamblia

Han

Collins

2012

International Journal of Proteomics

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Giardia lamblia is an “important” pathogen of humans, but as a diplomonad excavate it is evolutionarily distant from other eukaryotes and relatively little is known about its core metabolic pathways. KEGG, the widely referenced site for providing information of metabolism, does not yet include many enzymes from Giardia species. Here we identify Giardia's core sugar metabolism using standard bioinformatic approaches. By comparing Giardia proteomes with known enzymes from other species, we have identified enzymes in the glycolysis pathway, as well as some enzymes involved in the TCA cycle and oxidative phosphorylation. However, the majority of enzymes from the latter two pathways were not identifiable, indicating the likely absence of these functionalities. We have also found enzymes from the Giardia glycolysis pathway that appear more similar to those from bacteria. Because these enzymes are different from those found in mammals, the host organisms for Giardia, we raise the possibility that these bacteria-like enzymes could be novel drug targets for treating Giardia infections.

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Section: Resultssupporting

confidence: 88%

Reconstruction of Sugar Metabolic Pathways of Giardia lamblia

Han

Collins

2012

International Journal of Proteomics

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“…The excavates may not define a monophyletic group and are usually thought to have diverged close to the root of the eukaryotic tree. From the point of view of storage polysaccharides, among the two major excavate divisions, the amitochondriate metamonads and the discoba that contain discoid cristae within the mitochondria, only the former seems to accumulate glycogen as storage polysaccharide (Ladeira et al 2005;Manners and Ryley 1955), while the latter (with organisms such as Naegleria, Trypanosoma, or Euglena) are reported to contain either "-glucans, such as paramylon, or mannans, or both. The metamonads have a glycogen metabolism network resembling that of Amoebozoa (see Fig.…”

Section: Glycogen Metabolism In Excavatesmentioning

confidence: 97%

The Transition from Glycogen to Starch Metabolism in Cyanobacteria and Eukaryotes

Ball

Colleoni

Arias

2015

Starch

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'-1,4-linked glucan chains branched through '-1,6 glucosidic lineages define the most frequently found storage polysaccharides in living cells. These glucans come in two very distinct forms known as glycogen and starch. The small water-soluble glycogen particles distribute widely in Archaea, Bacteria, and heterotrophic eukaryotes, while semicrystalline solid starch seems to be restricted to photosynthetic eukaryotes. This review focusses on the so-called glycosylnucleotide-dependent pathway of starch and glycogen synthesis. Through comparative biochemistry of storage polysaccharide metabolism in distinct clades, we will review the evidence sustaining that starch has evolved from preexisting glycogen metabolism several times during the evolution of photosynthetic eukaryotes and cyanobacteria. This review will also describe the possible function of storage polysaccharide metabolism in establishing metabolic symbiosis during plastid endosymbiosis. We will detail the evidence sustaining that storage polysaccharide metabolism was used by three distinct organisms to establish a tripartite symbiosis that facilitated metabolic integration of free-living cyanobacteria into evolving organelles.

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“…Therefore, glycosidic compounds in these organisms play an important role in attachment and invasion to host cells and also for induction and modulation of the host immune response [45]. Besides, the involvement of UDP-Glc and UDP-Gal as key metabolites in G. lamblia is supported by: (i) the parasite ability to accumulate glycogen (for storage of carbon and energy, which determine survival and pathogenic capacity) [11,12]; and (ii) Gal represents a 14 and 26% of total sugars present in glycosidic structures of trophozoites and cyst membranes, respectively [45].…”

Section: Discussionmentioning

confidence: 99%

“…It has been reported that G. lamblia accumulates glycogen for storage of carbon and energy [11,12]. To get a better picture of occurrence and synthesis of the reserve polysaccharide in G. lamblia we approached the study of UDP-Glc PPase, the enzyme that catalyzes synthesis of the glycosyl donor (UDP-Glc) for glycogen elongation in heterotrophic eukaryotes [16,17].…”

Section: Cloning and Heterologous Expression Of G Lamblia Genes Encomentioning

confidence: 99%

“…The protective cystic wall comprises a characteristic Nacetyl-galactosamine polysaccharide and the structure is responsible for the parasite survival outside the host [9,10]. Furthermore, G. lamblia accumulates glycogen, which serves as an energy reserve in trophozoites [11] and also plays a critical role in their differentiation to cyst forms [12].…”

Section: Introductionmentioning

confidence: 99%

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