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The host targeting motif in exported Plasmodium proteins is cleaved in the parasite endoplasmic reticulum.

ABSTRACT: During the blood stage of its lifecycle, the malaria parasite resides and replicates inside a membrane vacuole within its host cell, the human erythrocyte. The parasite exports many proteins across the vacuole membrane and into the host cell cytoplasm. Most exported proteins are characterized by the presence of a host targeting (HT) motif, also referred to as a Plasmodium export element (PEXEL), which corresponds to the consensus sequence RxLxE/D/Q. During export the HT motif is cleaved by an unknown protease. Here, we generate parasite lines expressing HT motif containing proteins that are localized to different compartments within the parasite or host cell. We find that the HT motif in a protein that is retained in the parasite endoplasmic reticulum is cleaved and N-acetylated as efficiently as a protein that is exported. This shows that cleavage of the HT motif occurs early in the secretory pathway, in the parasite endoplasmic reticulum.

SUBMITTER: Osborne AR

PROVIDER: S-EPMC2843544 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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The host targeting motif in exported Plasmodium proteins is cleaved in the parasite endoplasmic reticulum.

Osborne Andrew R AR Speicher Kaye D KD Tamez Pamela A PA Bhattacharjee Souvik S Speicher David W DW Haldar Kasturi K

Molecular and biochemical parasitology 20100201 1

During the blood stage of its lifecycle, the malaria parasite resides and replicates inside a membrane vacuole within its host cell, the human erythrocyte. The parasite exports many proteins across the vacuole membrane and into the host cell cytoplasm. Most exported proteins are characterized by the presence of a host targeting (HT) motif, also referred to as a Plasmodium export element (PEXEL), which corresponds to the consensus sequence RxLxE/D/Q. During export the HT motif is cleaved by an un ...[more]

PMID: 20117149

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Project description:Studies of the Plasmodium falciparum transcriptome have shown that the tightly controlled progression of the parasite through the intra-erythrocytic developmental cycle (IDC) is accompanied by a continuous gene expression cascade in which most expressed genes exhibit a single transcriptional peak. Because the biochemical and cellular functions of most genes are mediated by the encoded proteins, understanding the relationship between mRNA and protein levels is crucial for inferring biological activity from transcriptional gene expression data. Although studies on other organisms show that <50% of protein abundance variation may be attributable to corresponding mRNA levels, the situation in Plasmodium is further complicated by the dynamic nature of the cyclic gene expression cascade. In this study, we simultaneously determined mRNA and protein abundance profiles for P. falciparum parasites during the IDC at 2-hour resolution based on oligonucleotide microarrays and two-dimensional differential gel electrophoresis protein gels. We find that most proteins are represented by more than one isoform, presumably because of post-translational modifications. Like transcripts, most proteins exhibit cyclic abundance profiles with one peak during the IDC, whereas the presence of functionally related proteins is highly correlated. In contrast, the abundance of most parasite proteins peaks significantly later (median 11 h) than the corresponding transcripts and often decreases slowly in the second half of the IDC. Computational modeling indicates that the considerable and varied incongruence between transcript and protein abundance may largely be caused by the dynamics of translation and protein degradation. Furthermore, we present cyclic abundance profiles also for parasite-associated human proteins and confirm the presence of five human proteins with a potential role in antioxidant defense within the parasites. Together, our data provide fundamental insights into transcript-protein relationships in P. falciparum that are important for the correct interpretation of transcriptional data and that may facilitate the improvement and development of malaria diagnostics and drug therapy.

Dataset Information

The host targeting motif in exported Plasmodium proteins is cleaved in the parasite endoplasmic reticulum.

Publications

The host targeting motif in exported Plasmodium proteins is cleaved in the parasite endoplasmic reticulum.

Similar Datasets

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