Sub-cellular localization and post-translational modifications of the Plasmodium yoelii enolase suggest moonlighting functions

Pal-Bhowmick, Ipsita; Vora, Hardeep K.; Jarori, Gotam K.

doi:10.1186/1475-2875-6-45

Cited by 62 publications

(59 citation statements)

References 27 publications

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“…In Plasmodium, enolase is present on the surface as well as in the nucleus, as observed through IFA and IEM data presented in this paper. Our biochemical analyses of subcellular fractions of P. yoelii have also provided similar results (34). The nuclear presence of enolase has also been reported in the closely related apicomplexan Toxoplasma gondii.…”

Section: Discussionsupporting

confidence: 86%

Protective Properties and Surface Localization ofPlasmodium falciparumEnolase

et al. 2007

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The enolase protein of the human malarial parasite Plasmodium falciparum has recently been characterized. Apart from its glycolytic function, enolase has also been shown to possess antigenic properties and to be present on the cell wall of certain invasive organisms, such as Candida albicans. In order to assess whether enolase of P. falciparum is also antigenic, sera from residents of a region of Eastern India where malaria is endemic were tested against the recombinant P. falciparum enolase (r-Pfen) protein. About 96% of immune adult sera samples reacted with r-Pfen over and above the seronegative controls. Rabbit anti-r-Pfen antibodies inhibited the growth of in vitro cultures of P. falciparum. Mice immunized with r-Pfen showed protection against a challenge with the 17XL lethal strain of the mouse malarial parasite Plasmodium yoelii. The antibodies raised against r-Pfen were specific for Plasmodium and did not react to the host tissues. Immunofluorescence as well as electron microscopic examinations revealed localization of the enolase protein on the merozoite cell surface. These observations establish malaria enolase to be a potential protective antigen.Malaria continues to be a life-threatening infectious disease in the tropical world. Despite tremendous efforts to control the malaria epidemic, current prophylaxis and drug treatments are proving insufficient. The extensive spreading of drug-resistant Plasmodium strains as well as insecticide-resistant mosquitoes makes it urgent to develop an effective malaria vaccine. Long years of antigen identification and characterization have yielded many potential vaccine candidates, but developing an effective malaria vaccine has remained an incredibly difficult challenge (17). It has been observed that immunity to the disease develops gradually, after many attacks and over many years, in adults living in areas where malaria is endemic (2). The successful passive transfer of this immunity by injecting antibodies from malaria-immune persons to children susceptible to malaria has demonstrated that antibodies alone can trigger protection (5, 9, 58). These experiments have worked across geographical borders, as immunoglobulin G (IgG) from malaria-immune West Africans have cured East Africans as well as Thai malaria patients (5). The nature of this immunity is poorly understood at the molecular level. However, attempts have been made to identify antigens, the humoral response against which leads to protection. Seroepidemiological studies have identified several specific malarial blood-stage antigens including ring-infected erythrocyte surface antigen (10), apical membrane antigen (53), and PfP0, a conserved ribosomal protein (7,18,24), as protective antigens.Enolase has been reported to be present on the cell surface of several organisms (38). It is also considered to be a major immunostimulatory protein in the case of visceral leishmaniasis (19). Enolase has been demonstrated to play a protective role in Candida albicans infection (31, 41, 55). Recently, it has also been ...

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Section: Discussionsupporting

confidence: 86%

Protective Properties and Surface Localization ofPlasmodium falciparumEnolase

et al. 2007

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“…Further investigation showed that this accumulation was due to enzymatically inactive enolase and that the accumulation was on the cell surface of these parasites. Whereas enolase functions in carbohydrate metabolism in a number of organisms, it has also recently been shown to function as a virulence factor in bacterial pathogens, such as Bacillus anthracis (41) and Streptococcus pneumoniae (42) as well as in protozoan parasites like Toxoplasma gondii (43) and Plasmodium (34), where it acts as a cell surface ligand. In fact, in Leishmania, surface-associated enolase was previously documented and shown to bind host plasminogen (44).…”

Section: Discussionmentioning

confidence: 99%

“…In the malaria parasite Plasmodium yoelii, different phosphorylated isoforms of enolase were localized to the parasite membrane (34). It was recently found that inactive forms of enolase are associated with the plasma membrane of L. mexicana, where they perform a function independent of the classical enzymatic activity (14).…”

Section: Opb(ϫ/ϫ) Parasites Lose the Major Serinementioning

confidence: 99%

The Oligopeptidase B of Leishmania Regulates Parasite Enolase and Immune Evasion

Swenerton¹,

Zhang²,

Sajid

et al. 2011

Journal of Biological Chemistry

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Proteases are a ubiquitous group of enzymes that play key roles in the life cycle of parasites, in the host-parasite relationship, and in the pathogenesis of parasitic diseases. Furthermore, proteases are targets for the development of new antiparasitic therapy. Protozoan parasites like Leishmania predominantly express Clan CA cysteine proteases for key life cycle functions. It was therefore unexpected to find a high level of serine protease activity expressed by Leishmania donovani. Purification of this activity followed by mass spectrometry identified oligopeptidase B (OPB; Clan SC, family S9A) as the responsible enzyme. This was confirmed by gene knock-out of OPB, which resulted in the disappearance of the detected serine protease activity of Leishmania extracts. To delineate the specific role of OPB in parasite physiology, proteomic analysis was carried out on OPB(؊/؊) versus wild type parasites. Four protein species were significantly elevated in OPB(؊/؊) parasites, and all four were identified by mass spectrometry as enolase. This increased enolase was enzymatically inactive and associated with the parasite membrane. Aside from its classic role in carbohydrate metabolism, enolase was recently found to localize to membranes, where it binds host plasminogen and functions as a virulence factor for several pathogens. As expected, there was a striking alteration in macrophage responses to Leishmania when OPB was deleted. Whereas wild type parasites elicited little, if any, response from infected macrophages, OPB(؊/؊) parasites induced a massive up-regulation in gene transcription. Additionally, these OPB(؊/؊) parasites displayed decreased virulence in the murine footpad infection model.Proteases are a ubiquitous group of enzymes functioning in nearly all biological phenomena. In protozoan parasites, proteases play key roles in life cycle transition, host invasion, parasite immune evasion, and the pathogenesis of parasitic diseases (1, 2). At least 50 cysteine proteases and twenty serine proteases are known to exist in the Leishmania genome (3-5).The molecular evolution of proteases shows a striking dichotomy between the predominant Clan CA cysteine proteases of protozoa and primitive metazoa and the dominant trypsin family (S1A) serine proteases of vertebrates (6). It was therefore unexpected to find that Leishmania donovani, Leishmania major, and Leishmania mexicana (but not the related kinetoplastid parasite, Trypanosoma cruzi) express high levels of serine protease activity, relative to cysteine protease activity in parasite extracts.To delineate the character of this serine protease activity, it was purified from Leishmania extracts and identified as Clan SC, family S9A oligopeptidase B by mass spectrometry. Oligopeptidase B (OPB) 2 has been identified in other protozoa, including T. cruzi, Trypanosoma brucei, and Trypanosoma evansi (7-9). These enzymes represent a subfamily of potential chemotherapeutic targets (10) because their inhibitors have been shown to be trypanocidal (4,11,12). OPB of T. cruzi is i...

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“…Though generally found in the cytoplasm, a number of studies have identified ␣-enolase on the surfaces of many cell types (43). Furthermore, in a recent study, a small fraction of enolase from the malarial parasite Plasmodium yoeli was found to be associated with cell membranes and cytoskeletal elements (42). This makes enolase an interesting candidate for mediating the interactions between EhLimA and the cytoskeleton and/or lipid rafts.…”

Section: Discussionmentioning

confidence: 99%

EhLimA, a Novel LIM Protein, Localizes to the Plasma Membrane inEntamoeba histolytica

2007

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The parasitic protozoan Entamoeba histolytica relies on a very dynamic cytoskeleton in order to invade and survive in host tissues. Identification of cytoskeletal elements is key to understanding these processes. Here we present the characterization of EhLimA, the first LIM protein of E. histolytica. EhLimA consists of a single LIM domain at its N terminus and exhibits the highest degree of homology with DdLimE from Dictyostelium discoideum. Immunofluorescence localization of EhLimA using anti-EhLimA antibodies revealed that EhLimA is highly concentrated at the plasma membrane of cells. Silencing or overexpression of the EhLimA gene did not have a significant effect on the growth or morphology of the parasite. EhLimA associates with the cytoskeleton as demonstrated by the enrichment of the protein in cytoskeleton fractions as well as in pull-down assays that revealed that cytoskeleton association involves interaction with actin. EhLimA binding to actin was shown to be dependent on the N-terminal LIM domain of EhLimA, as removal of even half of the LIM domain resulted in almost complete inhibition of the binding to actin. We also found that a portion of EhLimA floats to the lower-density regions of a sucrose gradient together with portions of the Gal-lectin light subunit and actin. Treatment of cells with the cholesterol-sequestering agent digitonin resulted in increased solubility of EhLimA. These results indicate that in addition to cytoskeletal association, EhLimA may also associate with lipid rafts in the parasite plasma membrane and suggest that EhLimA may be part of the molecular system connecting the actin cytoskeleton to membrane rafts.Many cellular functions are dependent on specific proteinprotein interactions. These protein-protein interactions are governed by a variety of protein binding domains one of which is the LIM domain. Since first described nearly 2 decades ago (21, 28, 57), LIM domain-containing proteins have been identified in a wide range of eukaryotes, including protozoa (16,30,45), plants (5,20,40), and yeast (Saccharomyces cerevisiae) (39), stressing the evolutionary importance of these proteins. In the parasitic protozoan Entamoeba histolytica, a few studies have revealed the presence of such proteins (17, 36), although to date, no LIM domain-containing proteins have been characterized in this organism. The name LIM is derived from the three developmentally regulated transcription factors, LIN-11 of Caenorhabditis elegans (21), Isl1 of rat (28), and MEC-3 of C. elegans (57) in which the LIM domain was initially identified. The LIM domain is a cysteine-rich motif consisting of two zinc finger-like modules and displaying the consensus sequence CX 2 CX 16-23 HX 2 CX 2 CX 2 CX 16-21 CX 2 (C/H/D/) (31). This domain is found in a variety of different proteins with diverse functions, including transcription factors and cytoskeleton-associated proteins, and may be found in association with other functional domains, such as homeodomains, protein kinase domains, or other protein binding domains (...

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Sub-cellular localization and post-translational modifications of the Plasmodium yoelii enolase suggest moonlighting functions

Cited by 62 publications

References 27 publications

Protective Properties and Surface Localization ofPlasmodium falciparumEnolase

Protective Properties and Surface Localization ofPlasmodium falciparumEnolase

The Oligopeptidase B of Leishmania Regulates Parasite Enolase and Immune Evasion

EhLimA, a Novel LIM Protein, Localizes to the Plasma Membrane inEntamoeba histolytica

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