Identification of protein complexes in detergent-resistant membranes of Plasmodium falciparum schizonts
Details
Publication Year 2007-08, Volume 154, Issue #2, Page 148-157
Journal Title
MOLECULAR AND BIOCHEMICAL PARASITOLOGY
Publication Type
Journal Article
Abstract
Merozoite surface proteins of the human malaria parasite Plasmodium falciparum are involved in initial contact with target erythrocytes, a process that begins a cascade of events required for successful invasion of these cells. In order to identify complexes that may play a role in invasion we purified detergent-resistant membranes (DRMs), known to be enriched in merozoite surface proteins, and used blue native-polyacrylamide gel electrophoresis (BN-PAGE) to isolate high molecular weight complexes for identification by mass spectrometry. Sixty-two proteins were detected and these mostly belonged to expected DRM proteins classes including GPI-anchored, multi-membrane spanning and rhoptry proteins. Proteins from seven known complexes were identified including MSP-1/7, the low (RAPI/2 and RAP1/3), and high (RhopHI/H2/H3) molecular weight rhoptry complexes, and the invasion motor complex (GAP45/GAP50/myosinA). Remarkably, a large proportion of identified spectra were derived from only 4 proteins: the GPI-anchored proteins MSP-1 and Pf92, the putative GPI-anchored protein Pf113 and RAP-1, the core component of the two RAP complexes. Each of these proteins predominated in high molecular weight species suggesting their aggregation in much larger complexes than anticipated. To demonstrate that the procedure had isolated novel complexes we focussed on MSP-1, which predominated as a distinct species at similar to 500 kDa by BN-PAGE, approximately twice its expected size. Chemical cross-linking supports the existence of a stable MSP-1 oligomer of similar to 500 kDa, probably comprising a highly stable homodimeric species. Our observations also suggests that oligomerization of MSP-1 is likely to occur outside the C-terminal epidermal growth factor (EGF)-like domains. Confirmation of MSP-1 oligomerization, together with the isolation of a number of known complexes by BN-PAGE, makes it highly likely that novel interactions occur amongst members of this proteome. (c) 2007 Elsevier BX All rights reserved.
Publisher
ELSEVIER SCIENCE BV
Keywords
MEROZOITE SURFACE PROTEIN-1; RHOPTRY PROTEIN; PARASITOPHOROUS VACUOLE; MALARIA PARASITES; CROSS-LINKING; LIFE-CYCLE; INVASION; GENE; ERYTHROCYTES; EXPRESSION
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Creation Date: 2007-08-01 12:00:00
Last Modified: 0001-01-01 12:00:00
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