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Escherichia coli mediated resistance of Entamoeba histolytica to oxidative stress is triggered by oxaloacetate.

ABSTRACT: Amebiasis, a global intestinal parasitic disease, is due to Entamoeba histolytica. This parasite, which feeds on bacteria in the large intestine of its human host, can trigger a strong inflammatory response upon invasion of the colonic mucosa. Whereas information about the mechanisms which are used by the parasite to cope with oxidative and nitrosative stresses during infection is available, knowledge about the contribution of bacteria to these mechanisms is lacking. In a recent study, we demonstrated that enteropathogenic Escherichia coli O55 protects E. histolytica against oxidative stress. Resin-assisted capture (RAC) of oxidized (OX) proteins coupled to mass spectrometry (OX-RAC) was used to investigate the oxidation status of cysteine residues in proteins present in E. histolytica trophozoites incubated with live or heat-killed E. coli O55 and then exposed to H2O2-mediated oxidative stress. We found that the redox proteome of E. histolytica exposed to heat-killed E. coli O55 is enriched with proteins involved in redox homeostasis, lipid metabolism, small molecule metabolism, carbohydrate derivative metabolism, and organonitrogen compound biosynthesis. In contrast, we found that proteins associated with redox homeostasis were the only OX-proteins that were enriched in E. histolytica trophozoites which were incubated with live E. coli O55. These data indicate that E. coli has a profound impact on the redox proteome of E. histolytica. Unexpectedly, some E. coli proteins were also co-identified with E. histolytica proteins by OX-RAC. We demonstrated that one of these proteins, E. coli malate dehydrogenase (EcMDH) and its product, oxaloacetate, are key elements of E. coli-mediated resistance of E. histolytica to oxidative stress and that oxaloacetate helps the parasite survive in the large intestine. We also provide evidence that the protective effect of oxaloacetate against oxidative stress extends to Caenorhabditis elegans.

SUBMITTER: Shaulov Y

PROVIDER: S-EPMC6181410 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Escherichia coli mediated resistance of Entamoeba histolytica to oxidative stress is triggered by oxaloacetate.

Shaulov Yana Y Shimokawa Chikako C Trebicz-Geffen Meirav M Nagaraja Shruti S Methling Karen K Lalk Michael M Weiss-Cerem Lea L Lamm Ayelet T AT Hisaeda Hajime H Ankri Serge S

PLoS pathogens 20181011 10

Amebiasis, a global intestinal parasitic disease, is due to Entamoeba histolytica. This parasite, which feeds on bacteria in the large intestine of its human host, can trigger a strong inflammatory response upon invasion of the colonic mucosa. Whereas information about the mechanisms which are used by the parasite to cope with oxidative and nitrosative stresses during infection is available, knowledge about the contribution of bacteria to these mechanisms is lacking. In a recent study, we demons ...[more]

PMID: 30308066

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Project description:The protozoan parasite, Entamoeba histolytica, invades the host colon causing significant tissue destruction and inflammation. Upon host infection, the parasite is confronted with reactive oxygen and nitrogen species (ROS/RNS) that cause large-scale changes in gene expression profiles, which likely support the parasite's adaptation to the host environment. We have previously identified oxidative and nitrosative stress responsive genes using whole-genome expression profiling. Functional studies on two such genes are now reported and demonstrate that they have roles in parasite virulence. EHI_056680 encodes a small hypothetical protein named E. histolytica stress-induced adhesion factor (EhSIAF); EHI_188210 encodes a putative phospholipid transporting P-type ATPase/flippase (EhPTPA). Over-expression of each protein in E. histolytica trophozoites enhanced parasite survival in response to oxidative stress. Exposure to oxidative and nitrosative stress did not affect the localization of EhSIAF or EhPTPA but markedly increased EhPTPA protein levels. Interestingly, over-expression of each gene resulted in parasites with increased adherence to healthy mammalian cells, but increased adherence to apoptotic cells was noted only in EhSIAF over-expressing parasites. However, despite having increased adherence to both healthy and apoptotic host cells, EhSIAF-over-expressing parasites were reduced in their ability to destroy mammalian cell monolayers, raising the intriguing possibility that EhSIAF over-expression caused signaling defects or resulted in a dominant negative phenotype. Over-expression of EhSIAF and EhPTPA also resulted in decreased motility in a transwell motility assay. Thus, we have confirmed that two genes that are upregulated by ROS confer increased resistance to oxidative stress and have identified an unexpected role of EhSIAF and EhPTPA in host cell adherence and a role of EhSIAF in parasite virulence. Our data imply that stress response genes may play multi-factorial roles in amoebic pathogenesis.

Project description:Characterization of the human microbiota is providing new insightsinto the complexity of host–parasite–bacterium relationships. Amoebiasis (an intestinal infection affecting a large proportion of the population in many countries worldwide) is caused by the amoebic parasite Entamoeba histolytica. During amoebiasis, the parasite encounters several types of stress as a result of the host’s response to infection. Given that E. histolytica phagocytises bacteria in the intestinal lumen, we hypothesized that enteric bacteria can influence the course of an amoebic infection. Hence, we used live Escherichia coli O55 as a pertinent model of the bacterial community’s contribution to amoebic responses during host- induced stress. By measuring amoebic survival, we found that live E. coli protected E. histolytica against oxidative stress (OS) but not against nitrosative stress. E. coli– associated protection is correlated with massive transcriptionalchanges in amoebic genes acquired through lateral transfer from the bacterial kingdom, including genes coding for proteinscontaining leucine-rich repeat (LRR) motifs. The transcriptome profile triggered by OS and E. coli was also observed with other enteric bacteria, including pathogens and non-pathogens. In contrast, exposure to a probiotic resulted in a different transcriptome profile. The present study shows that OS and live bacteria together modulate 84 of E. histolytica’s 137 LRR protein genes. The LRR proteins are involvedin protein-ligand and protein-protein interactions – especially in proteins that interact with bacteria as part of the innate immune response in mammals and plants, such as Toll-like receptors. The structural and functional homology of LRRs and TLRs identified here suggest that despite its old age in evolutionary terms, the protozoan E. histolytica displays key characteristics of higher eukaryotes’ innate immune systems. We conclude that components of innate immunity existed in the common ancestor of plants and animals

Project description: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 [Formula: see text] 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 [Formula: see text], 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.IMPORTANCEEntamoeba 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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Escherichia coli mediated resistance of Entamoeba histolytica to oxidative stress is triggered by oxaloacetate.

Publications

Escherichia coli mediated resistance of Entamoeba histolytica to oxidative stress is triggered by oxaloacetate.

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