Abstract:SURFIN 4.2 is a parasite-infected red blood cell (iRBC) surface associated protein of Plasmodium falciparum. To analyze the region responsible for the intracellular trafficking of SURFIN 4.2 to the iRBC and Maurer's clefts, a panel of transgenic parasite lines expressing recombinant SURFIN 4.2 fused with green fluorescent protein was generated and evaluated for their localization. We found that the cytoplasmic region containing a tryptophan rich (WR) domain is not necessary for trafficking, whereas the transme… Show more
“…However, NTC-4.2WRD2-GFP produced signals beyond the PVM with a diffused localization pattern in the iRBCs, which only partially co-localized with the Maurer’s cleft marker SBP1 and with PfEMP1, suggesting that it was likely transported beyond Maurer’s clefts and to the RBC cytosol or membrane (Fig. 1b), a result that is consistent with previous reports [6, 19]. Fig.…”
Section: Resultssupporting
confidence: 91%
“…In the current study, WRD2 shared the most similarity between two known exported SURFINs, SURFIN 4.1 and SURFIN 4.2 . Previous data have shown that recombinant SURFIN 4.2 containing WRDs were mainly detected in Triton X-100 insoluble fractions, compared to the one without WRD, and also exhibited a unique localization pattern in the iRBC cytosol, implying a direct interaction of these SURFIN 4.2 with the RBC membrane [6]. Consistently, by fusing the conserved WRD2 of SURFIN 4.2 with the minimum Maurer’s cleft targeting motifs present in SURFIN 4.1 [18], the recombinant NTC-4.2WRD2 also was targeted to the iRBC cytosol.…”
Section: Discussionmentioning
confidence: 99%
“…Maurer’s clefts are membranous structures involved in sorting and translocating parasite proteins to the iRBC membrane [4, 5]. These extensive modifications of the iRBC dramatically alter its morphology, antigenicity and functions, including the appearance of knob protrusions on the iRBC surface, increased rigidity and poor deformability of iRBC, and increased adhesiveness of the iRBC to the endothelium [4, 6, 7]. Some exported proteins such as PfEMP1, PfEMP3, MESA, Pf332, PfSBP1, KAHRP1, and RESA interact with RBC membrane skeleton [7–13].…”
Background
Plasmodium falciparum dramatically alters the morphology and properties of the infected red blood cells (iRBCs). A large group of exported proteins participate in these parasite-host interactions occurring at the iRBC membrane skeleton. SURFIN4.2 is one of iRBC surface protein that belongs to surface-associated interspersed protein (SURFIN) family. Although the intracellular tryptophan-rich domain (WRD) was proposed to be important for the translocation of SURFINs from Maurer’s clefts to iRBC surface, the molecular basis of this observation has yet to be defined. The WRDs of P. falciparum SURFIN proteins and their orthologous Plasmodium vivax subtelomeric transmembrane proteins (PvSTPs) show homology to the intracellular regions of PfEMP1 and Pf332, both of which are involved in RBC membrane skeleton interactions, and contribute to malaria pathology.MethodsTwo transfected lines expressing recombinant SURFINs (NTC-GFP and NTC-4.2WRD2-GFP) of the 3D7 sequence were generated by transfection in P. falciparum. In vitro binding assays were performed by using recombinant WRDs of SURFIN4.2/PvSTP2 and inside-out vesicles (IOVs). The interactions between the recombinant WRDs of SURFIN4.2/PvSTP2 with actin and spectrin were evaluated by the actin spin down assay and an enzyme-linked immunosorbent assay based binding assays, respectively.ResultsThe recombinant SURFINs (NTC-4.2WRD2-GFP), in which the second WRD from SURFIN4.2 was added back to NTC-GFP, show diffused pattern of fluorescence in the iRBC cytosol. Furthermore, WRDs of SURFIN4.2/PvSTP2 were found to directly interact with the IOVs of RBC, with binding affinities ranging from 0.26 to 0.68 μM, values that are comparable to other reported parasite proteins that bind to the RBC membrane skeleton. Further experiments revealed that the second WRD of SURFIN4.2 bound to F-actin (K
d = 5.16 μM) and spectrin (K
d = 0.51 μM).ConclusionsBecause PfEMP1 and Pf332 also bind to actin and/or spectrin, the authors propose that the interaction between WRD and RBC membrane skeleton might be a common feature of WRD-containing proteins and may be important for the translocation of these proteins from Maurer’s clefts to the iRBC surface. The findings suggest a conserved mechanism of host-parasite interactions and targeting this interaction may disrupt the iRBC surface exposure of Plasmodium virulence-related proteins.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-017-1772-5) contains supplementary material, which is available to authorized users.
“…However, NTC-4.2WRD2-GFP produced signals beyond the PVM with a diffused localization pattern in the iRBCs, which only partially co-localized with the Maurer’s cleft marker SBP1 and with PfEMP1, suggesting that it was likely transported beyond Maurer’s clefts and to the RBC cytosol or membrane (Fig. 1b), a result that is consistent with previous reports [6, 19]. Fig.…”
Section: Resultssupporting
confidence: 91%
“…In the current study, WRD2 shared the most similarity between two known exported SURFINs, SURFIN 4.1 and SURFIN 4.2 . Previous data have shown that recombinant SURFIN 4.2 containing WRDs were mainly detected in Triton X-100 insoluble fractions, compared to the one without WRD, and also exhibited a unique localization pattern in the iRBC cytosol, implying a direct interaction of these SURFIN 4.2 with the RBC membrane [6]. Consistently, by fusing the conserved WRD2 of SURFIN 4.2 with the minimum Maurer’s cleft targeting motifs present in SURFIN 4.1 [18], the recombinant NTC-4.2WRD2 also was targeted to the iRBC cytosol.…”
Section: Discussionmentioning
confidence: 99%
“…Maurer’s clefts are membranous structures involved in sorting and translocating parasite proteins to the iRBC membrane [4, 5]. These extensive modifications of the iRBC dramatically alter its morphology, antigenicity and functions, including the appearance of knob protrusions on the iRBC surface, increased rigidity and poor deformability of iRBC, and increased adhesiveness of the iRBC to the endothelium [4, 6, 7]. Some exported proteins such as PfEMP1, PfEMP3, MESA, Pf332, PfSBP1, KAHRP1, and RESA interact with RBC membrane skeleton [7–13].…”
Background
Plasmodium falciparum dramatically alters the morphology and properties of the infected red blood cells (iRBCs). A large group of exported proteins participate in these parasite-host interactions occurring at the iRBC membrane skeleton. SURFIN4.2 is one of iRBC surface protein that belongs to surface-associated interspersed protein (SURFIN) family. Although the intracellular tryptophan-rich domain (WRD) was proposed to be important for the translocation of SURFINs from Maurer’s clefts to iRBC surface, the molecular basis of this observation has yet to be defined. The WRDs of P. falciparum SURFIN proteins and their orthologous Plasmodium vivax subtelomeric transmembrane proteins (PvSTPs) show homology to the intracellular regions of PfEMP1 and Pf332, both of which are involved in RBC membrane skeleton interactions, and contribute to malaria pathology.MethodsTwo transfected lines expressing recombinant SURFINs (NTC-GFP and NTC-4.2WRD2-GFP) of the 3D7 sequence were generated by transfection in P. falciparum. In vitro binding assays were performed by using recombinant WRDs of SURFIN4.2/PvSTP2 and inside-out vesicles (IOVs). The interactions between the recombinant WRDs of SURFIN4.2/PvSTP2 with actin and spectrin were evaluated by the actin spin down assay and an enzyme-linked immunosorbent assay based binding assays, respectively.ResultsThe recombinant SURFINs (NTC-4.2WRD2-GFP), in which the second WRD from SURFIN4.2 was added back to NTC-GFP, show diffused pattern of fluorescence in the iRBC cytosol. Furthermore, WRDs of SURFIN4.2/PvSTP2 were found to directly interact with the IOVs of RBC, with binding affinities ranging from 0.26 to 0.68 μM, values that are comparable to other reported parasite proteins that bind to the RBC membrane skeleton. Further experiments revealed that the second WRD of SURFIN4.2 bound to F-actin (K
d = 5.16 μM) and spectrin (K
d = 0.51 μM).ConclusionsBecause PfEMP1 and Pf332 also bind to actin and/or spectrin, the authors propose that the interaction between WRD and RBC membrane skeleton might be a common feature of WRD-containing proteins and may be important for the translocation of these proteins from Maurer’s clefts to the iRBC surface. The findings suggest a conserved mechanism of host-parasite interactions and targeting this interaction may disrupt the iRBC surface exposure of Plasmodium virulence-related proteins.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-017-1772-5) contains supplementary material, which is available to authorized users.
“…Here, we investigate immune responses to protein products of three genes expressed at the merozoite stage that showed evidence of balancing selection in a genome-wide scan of a Gambian population (18), with similar results when tested separately in a Kenyan population (16). They are MSPDBL1 (also referred to as MSP3.4 [20]; gene locus PF3D7_1035700, previously PF10_0348) and MSPDBL2 (also referred to as MSP3.8 [20]; gene locus PF3D7_1036300, previously PF10_0355), which are members of the MSP3 family possessing a central Duffy-binding-like (DBL) region, and SURFIN4.2 (a member of the surf gene family; locus PF3D7_0424400, previously PFD1160w) (16, 21, 22). Recent studies have indicated a role for both MSPDBL1 and MSPDBL2 in binding to the erythrocyte surface (23, 24), with the interaction mediated by the DBL region (24).…”
Prospective studies continue to identify malaria parasite genes with particular patterns of polymorphism which indicate they may be under immune selection, and the encoded proteins require investigation. Sixteen new recombinant protein reagents were designed to characterize three such polymorphic proteins expressed in Plasmodium falciparum schizonts and merozoites: MSPDBL1 (also termed MSP3.4) and MSPDBL2 (MSP3.8), which possess Duffy binding-like (DBL) domains, and SURFIN4.2, encoded by a member of the surface-associated interspersed (surf) multigene family. After testing the antigenicities of these reagents by murine immunization and parasite immunofluorescence, we analyzed naturally acquired antibody responses to the antigens in two cohorts in coastal Kenya in which the parasite was endemic (Chonyi [n = 497] and Ngerenya [n = 461]). As expected, the prevalence and levels of serum antibodies increased with age. We then investigated correlations with subsequent risk of clinical malaria among children <11 years of age during 6 months follow-up surveillance. Antibodies to the polymorphic central region of MSPDBL2 were associated with reduced risk of malaria in both cohorts, with statistical significance remaining for the 3D7 allelic type after adjustment for individuals' ages in years and antibody reactivity to whole-schizont extract (Chonyi, risk ratio, 0.51, and 95% confidence interval [CI], 0.28 to 0.93; Ngerenya, risk ratio, 0.38, and 95% CI, 0.18 to 0.82). For the MSPDBL1 Palo Alto allelic-type antigen, there was a protective association in one cohort (Ngerenya, risk ratio, 0.53, and 95% CI, 0.32 to 0.89), whereas the other antigens showed no protective associations after adjustment. These findings support the prediction that antibodies to the polymorphic region of MSPDBL2 contribute to protective immunity.
“…One important feature of PNEP proteins is the presence of a transmembrane domain, since removal of this domain from the PNEPs MAHRP1, SBP1 and REX2 inhibited protein export [43,44]. Similarly, the transmembrane domain of SURFIN 4.2 was essential for protein trafficking to the infected erythrocyte and Maurer’s clefts [69]. …”
BackgroundCopper is an essential catalytic co-factor for metabolically important cellular enzymes, such as cytochrome-c oxidase. Eukaryotic cells acquire copper through a copper transport protein and distribute intracellular copper using molecular chaperones. The copper chelator, neocuproine, inhibits Plasmodium falciparum ring-to-trophozoite transition in vitro, indicating a copper requirement for malaria parasite development. How the malaria parasite acquires or secretes copper still remains to be fully elucidated.MethodsPlasmoDB was searched for sequences corresponding to candidate P. falciparum copper-requiring proteins. The amino terminal domain of a putative P. falciparum copper transport protein was cloned and expressed as a maltose binding fusion protein. The copper binding ability of this protein was examined. Copper transport protein-specific anti-peptide antibodies were generated in chickens and used to establish native protein localization in P. falciparum parasites by immunofluorescence microscopy.ResultsSix P. falciparum copper-requiring protein orthologs and a candidate P. falciparum copper transport protein (PF14_0369), containing characteristic copper transport protein features, were identified in PlasmoDB. The recombinant amino terminal domain of the transport protein bound reduced copper in vitro and within Escherichia coli cells during recombinant expression. Immunolocalization studies tracked the copper binding protein translocating from the erythrocyte plasma membrane in early ring stage to a parasite membrane as the parasites developed to schizonts. The protein appears to be a PEXEL-negative membrane protein.ConclusionPlasmodium falciparum parasites express a native protein with copper transporter characteristics that binds copper in vitro. Localization of the protein to the erythrocyte and parasite plasma membranes could provide a mechanism for the delivery of novel anti-malarial compounds.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
