The chitin biosynthesis pathway in Entamoeba and the role of glucosamine-6-P isomerase by RNA interference

Samanta, Sintu Kumar; Ghosh, Sudip Kumar

doi:10.1016/j.molbiopara.2012.09.011

Cited by 21 publications

(15 citation statements)

References 30 publications

(40 reference statements)

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“…It was postulated that enzymes of cell wall biosynthesis pathways could be targeted by potential antiprotozoal drugs (Spindler et al 1990 ). The anabolic GlcN6P deaminase was indicated as one of the potential targets for antiparasitic chemotherapy (Aguilar-Díaz et al 2011 ), which was confirmed by results of the gene silencing experiments (Samanta and Ghosh 2012 ). It seems interesting therefore to find out a molecular basis of an apparent uniqueness of this enzyme.…”

Section: Introductionmentioning

confidence: 80%

Heterogeneity of quaternary structure of glucosamine-6-phosphate deaminase from Giardia lamblia

et al. 2014

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The oligoHis-tagged versions of glucosamine-6-phosphate deaminase from Giardia lamblia (GlmNagB-HisN, GlmNagB-HisC) were constructed and purified to hear homogeneity, and their kinetic and structural properties were compared to those of the wild-type enzyme (GlmNagB). Introduction of the oligoHis tag at the GlmNagB C-terminus resulted in almost complete loss of the catalytic activity, while the catalytic properties of GlmNagB-HisN and GlmNagB were very similar. The recombinant and wild-type enzyme exhibits heterogeneity of the quaternary structure and in solution exists in three interconvertible forms, namely, monomeric, homodimeric, and homotetrameric. Although the monomeric form is prevalent, the monomer/dimer/tetramer ratios depended on protein concentration and fell within the range from 72:27:1 to 39:23:38. The enzyme is fully active in each of the oligomeric structures, efficiently catalyzes synthesis of D-glucosamine-6-phosphate from D-fructose-6-phosphate and ammonia, and its activity is not modified by GlcNAc6P, UDP-GlcNAc, or UDP-GalNAc. GlcN6P deaminase of G. lamblia represents a novel structural and functional type of enzyme of the NagB subfamily.

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Section: Introductionmentioning

confidence: 80%

Heterogeneity of quaternary structure of glucosamine-6-phosphate deaminase from Giardia lamblia

et al. 2014

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“…This sequence indicates the functional linkage of these two processes because cytoplasmic glycogen disappearance reflects the degradation of stored glycogen to provide a substrate for the synthesis of chitin. Glycogen hydrolysis provides D-glucose-1-phosphate via D-glucose, which is an essential substrate for the chitin synthetic pathway (Samanta and Ghosh, 2012). Intriguingly, in E. histolytica , the cyst-like structure formation was impaired by knockdown of the D-glucosamine 6-phosphate isomerase gene, which inhibits chitin synthesis (Aguilar-Díaz et al ., 2013).…”

Section: Discussionmentioning

confidence: 99%

The dynamics of ultrastructural changes during Entamoeba invadens encystation

Mousa¹,

Sakaguchi²,

Nakamura³

et al. 2020

Parasitology

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Entamoeba histolytica infection causes amoebiasis, which is a global public health problem. The major route of infection is oral ingestion of E. histolytica cysts, cysts being the sole form responsible for host-to-host transmission. Cysts are produced by cell differentiation from proliferative trophozoites in a process termed ‘encystation’. Therefore, encystation is an important process from a medical as well as a biological perspective. Previous electron microscopy studies have shown the ultrastructure of precysts and mature cysts; however, the dynamics of ultrastructural changes during encystation were ambiguous. Here, we analysed a series of Entamoeba invadens encysting cells by transmission electron microscopy. Entamoeba invadens is a model for encystation and the cells were prepared by short interval time course sampling from in vitro encystation-inducing cultures. We related sampled cells to stage conversion, which was monitored in the overall population by flow cytometry. The present approach revealed the dynamics of ultrastructure changes during E. invadens encystation. Importantly, the results indicate a functional linkage of processes that are crucial in encystation, such as glycogen accumulation and cyst wall formation. Hence, this study provides a reference for studying sequential molecular events during Entamoeba encystation.

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“…To understand the in vivo role of Entamoeba TopoII during normal growth as well as encystation, we employed the dsRNA‐mediated gene silencing strategy reported by Samanta and Ghosh . The dsRNA specific to EitopoII and EhtopoII were expressed in RNase III‐deficient E. coli HT115 cells (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Eh and Ei trophozoites were incubated in TYI or LG media containing 200 μg·mL −1 of the respective, purified TopoII‐specific dsRNA for various time points, based on the experiment, and the silencing efficiency was calculated using real‐time RT‐PCR . All RNAi studies were carried out with two controls: one without dsRNA and one with non‐specific dsRNA (from B. subtilis , as mentioned above).…”

Section: Methodsmentioning

confidence: 99%

Stress‐responsive Entamoeba topoisomerase II: a potential antiamoebic target

Varghese

Ghosh

2019

FEBS Letters

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Topoisomerases, the ubiquitous enzymes involved in all DNA processes across the biological world, are targets for various anticancer and antimicrobial agents. In Entamoeba histolytica, the causative agent of amebiasis, we found one of seven unexplored putative topoisomerases to be highly upregulated during heat shock and oxidative stress, and also during the late hours of encystation. Further analysis revealed the upregulated enzyme to be a eukaryotic type IIA topoisomerase (TopoII) with demonstrable activity in vitro. This enzyme is localized to newly forming nuclei during encystation. Gene silencing of the TopoII reduces viability and encystation efficiency. Notable susceptibility of Entamoeba TopoII to prokaryotic topoisomerase inhibitors opens up the possibility for exploring this enzyme as a new antiamoebic target.

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The chitin biosynthesis pathway in Entamoeba and the role of glucosamine-6-P isomerase by RNA interference

Cited by 21 publications

References 30 publications

Heterogeneity of quaternary structure of glucosamine-6-phosphate deaminase from Giardia lamblia

Heterogeneity of quaternary structure of glucosamine-6-phosphate deaminase from Giardia lamblia

The dynamics of ultrastructural changes during Entamoeba invadens encystation

Stress‐responsive Entamoeba topoisomerase II: a potential antiamoebic target

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