Crystal Structure of the Human tRNA Guanine Transglycosylase Catalytic Subunit QTRT1

Johannsson, Sven; Neumann, Piotr; Ficner, Ralf

doi:10.3390/biom8030081

Cited by 18 publications

(19 citation statements)

References 51 publications

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“…S3A and B available at https://datadryad.org/stash/share/Y6qAAIhEzUcPNlK16zSmOvPJyjd0bqUcPUz3mNw1fCg ), which interact together to form a heterodimer like the eukaryotic TGT enzyme ( Fig. 3A ) ( 29 ). To get more insights about the EhTGT enzyme, a polyhistidine-tagged EhQTRT1 and untagged EhQTRTD1 were cloned and coexpressed in E. coli .…”

Section: Resultsmentioning

confidence: 99%

Queuine Is a Nutritional Regulator of Entamoeba histolytica Response to Oxidative Stress and a Virulence Attenuator

Nagaraja

Cai

Sun

et al. 2021

mBio

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Queuosine is a naturally occurring modified ribonucleoside found in the first position of the anticodon of the transfer RNAs for Asp, Asn, His, and Tyr. Eukaryotes lack pathways to synthesize queuine, the nucleobase precursor to queuosine, and must obtain it from diet or gut microbiota. Here, we describe the effects of queuine on the physiology of the eukaryotic parasite Entamoeba histolytica, the causative agent of amebic dysentery. Queuine is efficiently incorporated into E. histolytica tRNAs by a tRNA-guanine transglycosylase (EhTGT) and this incorporation stimulates the methylation of C38 in tRNAGUCAsp. Queuine protects the parasite against oxidative stress (OS) and antagonizes the negative effect that oxidation has on translation by inducing the expression of genes involved in the OS response, such as heat shock protein 70 (Hsp70), antioxidant enzymes, and enzymes involved in DNA repair. On the other hand, queuine impairs E. histolytica virulence by downregulating the expression of genes previously associated with virulence, including cysteine proteases, cytoskeletal proteins, and small GTPases. Silencing of EhTGT prevents incorporation of queuine into tRNAs and strongly impairs methylation of C38 in tRNAGUCAsp, parasite growth, resistance to OS, and cytopathic activity. Overall, our data reveal that queuine plays a dual role in promoting OS resistance and reducing parasite virulence. IMPORTANCE Entamoeba histolytica is a unicellular parasite that causes amebiasis. The parasite resides in the colon and feeds on the colonic microbiota. The gut flora is implicated in the onset of symptomatic amebiasis due to alterations in the composition of bacteria. These bacteria modulate the physiology of the parasite and affect the virulence of the parasite through unknown mechanisms. Queuine, a modified nucleobase of queuosine, is exclusively produced by the gut bacteria and leads to tRNA modification at the anticodon loops of specific tRNAs. We found that queuine induces mild oxidative stress resistance in the parasite and attenuates its virulence. Our study highlights the importance of bacterially derived products in shaping the physiology of the parasite. The fact that queuine inhibits the virulence of E. histolytica may lead to new strategies for preventing and/or treating amebiasis by providing to the host queuine directly or via probiotics.

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Section: Resultsmentioning

confidence: 99%

Queuine Is a Nutritional Regulator of Entamoeba histolytica Response to Oxidative Stress and a Virulence Attenuator

Nagaraja

Cai

Sun

et al. 2021

mBio

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“…7-chloro-7-deazaguanine ( 12 ) and 7-nitro-7-deazaguanine ( 11 )), and a range of ester, carboxy/amide derivatives ( 13 – 20 ) and oximes ( 20 – 24 ). Ficner and colleagues ( 40 ) have reported the crystal structure of QTRT1 where electron density corresponding to bound queuine was detected in the active site. In this structure the cyclopentene moiety occupies a groove that is expanded by rotation of Ser231 away from the nucleobase.…”

Section: Discussionmentioning

confidence: 99%

The human tRNA-guanine transglycosylase displays promiscuous nucleobase preference but strict tRNA specificity

Fergus

Alqasem

Cotter

et al. 2021

Nucleic Acids Research

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Base-modification can occur throughout a transfer RNA molecule; however, elaboration is particularly prevalent at position 34 of the anticodon loop (the wobble position), where it functions to influence protein translation. Previously, we demonstrated that the queuosine modification at position 34 can be substituted with an artificial analogue via the queuine tRNA ribosyltransferase enzyme to induce disease recovery in an animal model of multiple sclerosis. Here, we demonstrate that the human enzyme can recognize a very broad range of artificial 7-deazaguanine derivatives for transfer RNA incorporation. By contrast, the enzyme displays strict specificity for transfer RNA species decoding the dual synonymous NAU/C codons, determined using a novel enzyme-RNA capture-release method. Our data highlight the broad scope and therapeutic potential of exploiting the queuosine incorporation pathway to intentionally engineer chemical diversity into the transfer RNA anticodon.

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“…To get information about the EhTGT structure, we built an in silico model of EhTGT subunits based on the Thermotoga maritima QTRT1 structure and murine QTRT2 structures. The prediction also suggested that EhQTRT1 and EhQTRTD1 are homodimers (Fig S3 A&B), which interact together to form a heterodimer like the eukaryotic TGT enzyme (Fig 3A)[28]. To get more insights about the EhTGT enzyme, a polyhistidine-tagged EhQTRT1 and untagged EhQTRTD1 was cloned and coexpressed in E. coli .…”

Section: Resultsmentioning

confidence: 99%

Queuine is a nutritional regulator ofEntamoeba histolyticaresponse to oxidative stress and a virulence attenuator

Nagaraja

Cai

Sun

et al. 2020

Preprint

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Queuosine is a naturally occurring modified ribonucleoside found in the first position of the anticodon of the transfer RNAs for Asp, Asn, His and Tyr. Eukaryotes lack pathways to synthesize queuine, the nucleobase precursor to queuosine, and must obtain it from diet or gut microbiota. Here we describe the effects of queuine on the physiology of the eukaryotic parasite, Entamoeba histolytica, the causative agent of amebic dysentery. Queuine is efficiently incorporated into E. histolytica tRNAs by a tRNA-guanine transglycosylase (EhTGT) and this incorporation stimulates the methylation of C 38 in tRNA Asp GTC . Queuine protects the parasite against oxidative stress (OS) and antagonizes the negative effect that oxidation has on translation by inducing the expression of genes involved in OS response, such as heat shock protein 70 (Hsp 70), antioxidant enzymes, and enzymes involved in DNA repair. On the other hand, queuine impairs E. histolytica virulence by downregulating the expression of genes previously associated with virulence, including cysteine proteases, cytoskeletal proteins, and small GTPases. Silencing of EhTGT prevents incorporation of queuine into tRNAs and strongly impairs methylation of C 38 in tRNA Asp GTC , parasite growth, resistance to OS, and cytopathic activity. Overall, our data reveal that queuine plays a dual role in promoting OS resistance and reducing parasite virulence.Amebiasis is an enormous global medical problem due to poor sanitary conditions and unsafe hygiene practices in many parts of the world. According to the World Health Organization, 50 million people in India, Southeast Asia, Africa, and Latin America suffer from amebic dysentery, with amebiasis causing the death of at least 100,000 people each year. Entamoeba histolytica, the etiologic agent of amebiasis, proliferate in the intestinal lumen and phagocytose resident gut flora.Over the last few decades, it has become evident that E. histolytica's pathogenicity is directly linked to the parasite's interaction with the gut microbiota [1]. This interaction is very selective because only those bacteria with the appropriate recognition molecules are ingested by the parasite [2]. It has been reported that the E. histolytica's association with specific intestinal bacteria changes the parasite's cell surface architecture [3,4]. It has also been reported that phagocytosis of pathogenic bacteria boosts E. histolytica's cytopathogenicity, increases the expression of Gal/GalNAc lectin on the cell surface, and boosts cysteine proteinase activity when trophozoites are co-cultured with the enteropathogenic Escherichia coli (EPEC) O55 or Shigella dysenteriae [5]. It has also been reported that bacteria-induced augmentation of E. histolytica's virulence is achieved only when the trophozoites phagocytose intact live cells [6]. The composition of the gut flora in patients suffering from amebiasis shows a significant decrease in the population size of Bacteroides, Clostridium coccoides, Clostridium leptum, Lactobacillus, and Campylobacter and an ...

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Crystal Structure of the Human tRNA Guanine Transglycosylase Catalytic Subunit QTRT1

Cited by 18 publications

References 51 publications

Queuine Is a Nutritional Regulator of Entamoeba histolytica Response to Oxidative Stress and a Virulence Attenuator

Queuine Is a Nutritional Regulator of Entamoeba histolytica Response to Oxidative Stress and a Virulence Attenuator

The human tRNA-guanine transglycosylase displays promiscuous nucleobase preference but strict tRNA specificity

Queuine is a nutritional regulator ofEntamoeba histolyticaresponse to oxidative stress and a virulence attenuator

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