Spontaneously releasedPlasmodium falciparum merozoites from culture possess glycoproteins

Heidrich, Hans-G.; Strych, Werner; Prehm, Peter

doi:10.1007/bf00927127

Cited by 25 publications

(6 citation statements)

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“…MSA 2, the second main molecule present on the Plasmodium falciparum merozoite surface, is a 35–56 kDa glycoprotein whose size and isoelectric point vary according to the parasite strain (1, 2). It is expressed during the late ring stage (≈ 12 h after merozoite invasion) and its maximal concentration is observed 42 h after invasion (3, 4). This antigen has been found to be associated with internal membranes in very mature multinucleated schizonts; it is present on the merozoite surface and residual bodies of all P. falciparum strains studied to date (5–9).…”

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confidence: 99%

Two MSA 2 peptides that bind to human red blood cells are relevant to Plasmodium falciparum merozoite invasion

Ocampo

Urquiza

Guzmán

et al. 2000

The Journal of Peptide Research

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Plasmodium falciparum merozoite membrane surface antigen 2 (MSA2) has been associated with the development of protective immunity against malaria. MSA2 antibodies were able to inhibit in vitro merozoite invasion. In our search for experimental evidence concerning the participation of MSA2 in merozoite invasion, 40 peptides were synthesized according to sequences reported for the CAMP and FC27 prototype Plasmodium strains. These peptides were purified, 125I-radiolabeled and tested for their ability to bind to erythrocytes. Two MSA2 synthetic peptides with high specific binding to human erythrocytes were found. The peptide coded 4044 (KNESKYSNTFINNAYNMSIR), located in the MSA2 N-terminal conserved region, has an affinity coefficient of 72 nM and showed a positive cooperativity for the receptor-ligand interaction. The other peptide, coded 4053 (NPNHKNAETNPKGKGEVQKP) and located in the central variable region of MSA2, has an affinity coefficient of 49nM and also showed a positive cooperativity for the receptor-ligand interaction. The binding capacity of these peptides is affected by erythrocytes treated with neuraminidase and trypsin, but it is not affected by chymotrypsin. Both of these sequences inhibit in vitro erythrocyte parasite invasion by up to 95% suggesting that they have an important role in the parasite's invasion process. Furthermore, as published previously [A. Saul et al. (1992) J. Immunol., 148, 208-211], a protective B epitope is included in the 4044 peptide sequence.

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confidence: 99%

Two MSA 2 peptides that bind to human red blood cells are relevant to Plasmodium falciparum merozoite invasion

Ocampo

Urquiza

Guzmán

et al. 2000

The Journal of Peptide Research

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“…Several proteins of erythrocytic stage P. falciparum are known to contain carbohydrates (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). The deduced amino acid sequences of the parasite proteins have potential N-glycosylation sites (7, 24 -26).…”

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confidence: 99%

Glycosylphosphatidylinositol Anchors Represent the Major Carbohydrate Modification in Proteins of Intraerythrocytic Stage Plasmodium falciparum

Gowda

Gupta

Davidson

1997

Journal of Biological Chemistry

136

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The nature and extent of carbohydrate modification in intraerythrocytic stage Plasmodium falciparum proteins have been controversial. This study describes the characterization of the carbohydrates in intraerythrocytic P. falciparum proteins and provides an overall picture of the nature of carbohydrate modification in the parasite proteins. P. falciparum strains were metabolically labeled with radioactive sugar precursors and ethanolamine at different developmental stages. The individual parasite proteins separated on SDS-polyacrylamide gels and whole parasite cell lysates were analyzed for the carbohydrate moieties. The results established the following: 1) glycosylphosphatidylinositol (GPI) anchors represent the major carbohydrate modification in the intraerythrocytic stage P. falciparum proteins; 2) in contrast to previous reports, O-linked carbohydrates are either absent or present only at very low levels in the parasite; and 3) P. falciparum contains low levels of N-glycosylation capability. The amount of N-linked carbohydrates in whole parasite proteins is ϳ6% compared with the GPI anchors attached to proteins based on radioactive GlcN incorporated into the proteins.The glycan cores of multiple parasite protein GPI anchors are all similar, consisting of protein-ethanolamine-phosphate-(Man␣1-2)6Man␣1-2Man␣1-6Man␣1-4GlcN. The fourth Man residues distal to GlcN of the GPI anchor glycan cores contain unidentified substituents that are susceptible to conditions of nitrous acid deamination. This unusual structural feature may contribute to the reported pathogenic properties of the P. falciparum GPI anchors.Malaria, a life-threatening disease caused by parasitic protozoa of the genus Plasmodium, is a major health problem throughout the tropical and subtropical regions of the world. Among the four species that infect humans, Plasmodium falciparum is the most virulent. New approaches such as vaccine development and novel therapeutic agents are urgently needed due to the emergence of parasite strains resistant to chloroquine and other commonly used drugs (1).Vaccines based on antigens of the blood stage parasite are under intensive study. A major focus has been on synthetic peptides or recombinant proteins of cell surface antigens (2-6). However, this approach has not been highly effective, although immunization with native cell surface proteins purified from the erythrocytic stage parasite is known to confer significant protective immunity (7-10). It is plausible that post-translational modifications play an important role in antigenicity. Accordingly, a basic understanding of such modifications may assist in the development of effective vaccines.Glycosylation is an often extensive post-translational modification of eukaryotic proteins. Carbohydrate moieties of glycoproteins perform a variety of functions including modulation of immunological properties, receptor-ligand interactions, sorting and localization of proteins, cell adhesion, and cell-cell communication (11). In addition, they contribute to protein conform...

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“…Other merozoite surface antigens, not related to the high molecular w¢!ght precursor, have been described. These include a giycoptotein with a molecular mass of 46 kDa observed in the FCBI strain [16,17,39,40]. Whether or not this antigen is the equivalent of a 56 kDa glycoprorein described by Stanley et al [62] in the FVO-strain remains to be seen.…”

Section: Discussionmentioning

confidence: 94%

“…The serum against another antigen, the 46 kDa merozoite surface antigen (which is not derived from the high molecular weight precursor, but is rather a protein syn-",hesised at the trophozoite stage and which is not processed during the schizogony cycle [17,40]) is recognised by the corresponding immune serum as a single band (Fig. 6).…”

Section: Production Of the Antiseramentioning

confidence: 99%

“…In one parasite strain at least 4 of these components at 83, 42, 36 and 19 kDa are derived from the precursor. The precursor, an antigenic glycoprotein which varies among P. falciparum strains in relative molecular mass (M r) from 185 to > 200 kDa, exhibits considerable antigenic and structural polymorphism within a single parasite species as well as maintaining conserved structures [11,13,15,17,19,20,26,27,[36][37][38]51,58,64,69]. The immunological importance of this molecule and/or its fragments has been indicated by antibodies directed against the precursor or its fragments which inhibit growth of P. falciparum in culture [3,55], and by partial protection of Aotus and Saimiri monkeys immunised with the precursor [14,[48][49][50]60].…”

Section: Introductionmentioning

confidence: 99%

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Isolation and functional characterization of Plasmodium falciparum merozoite antigens

Heidrich

1988

Biology of the Cell

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Spontaneously releasedPlasmodium falciparum merozoites from culture possess glycoproteins

Abstract: Using metabolic labeling techniques with either radioactive glucosamine or various sugars in synchronous Plasmodium falciparum cultures it was proven that merozoites isolated from such cultures possess glycoproteins. Biosynthesis and processing of these glycoproteins were investigated.

Cited by 25 publications

References 11 publications

Two MSA 2 peptides that bind to human red blood cells are relevant to Plasmodium falciparum merozoite invasion

Two MSA 2 peptides that bind to human red blood cells are relevant to Plasmodium falciparum merozoite invasion

Glycosylphosphatidylinositol Anchors Represent the Major Carbohydrate Modification in Proteins of Intraerythrocytic Stage Plasmodium falciparum

Isolation and functional characterization of Plasmodium falciparum merozoite antigens

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