Unknown,Transcriptomics,Genomics,Proteomics

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A crucial role of the zinc finger protein PfZnFP-G in sexual differentiation of the malaria parasites, Plasmodium falciparum

ABSTRACT: We described the biological role of a putative zinc finger protein (Plasmodb id: PF3D7_1008600), which plays an important role during the initiation and subsequent progression of gametocytogenesis in P. falciparum. Hence we termed the protein P. falciparum Zinc Finger Protein for Gametocytogenesis (PfZnFP-G). During the asexual intraerythrocyic developmental cycle (IDC), PfZnFP-G levels peak during the schizont stage during which it is localized in the nucleus. During the IDC, PfZnFP-G appears to be stochastically expressed in ~3% parasite population. Deactivation of PfZnFP-G appears to suppress, but not fully inhibit, production of gametocytes and vice versa overproduction of PfZnFP-G stimulates gametocytogenesis. In addition, PfZnFP-G is capable of associating with DNA binding preferentially to intergenic, promoter regions of the genome, and this binding correlates positively with transcription, particularly of other gametocyte specific genes. PfZnFP-G is also expressed in the mid-to-late gametocytes where it is present in the cytoplasm. Overall, these results suggest a dual function of PfZnFP-G in gametocytogenesis including: (i) commitment as a transcription factor and (ii) gametocyte maturation as a putative RNA binding protein. Transgenic 3D7 wild type parasite lines were generated with PfZnFP-G tagged, over-expressed and knocked-out. Transcriptional profiles across the parasite life cycle were generated. Genome occupancy of PfZnFP-G were also investigated and compared to the corresponding transcriptional profiles.

ORGANISM(S): Plasmodium falciparum

SUBMITTER: Yen-Hoon Luah

PROVIDER: E-GEOD-75295 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: Malaria is a one of the most important infectious diseases and is caused by parasitic protozoa of the genus Plasmodium. Previously, the quantitative characterization of the P. falciparum transcriptome demonstrated that the strictly controlled progression of these parasites through their intra-erythrocytic developmental cycle is accompanied by a continuous cascade of gene expression. Although such analyses have proven immensely useful, the precise correlations between transcript and protein abundance remain under-scrutinized. Results: Here, we present a quantitative time-course analysis of relative protein abundance for schizont-stage parasites (34-46 hours post-invasion) based on 2D-gel electrophoresis of protein samples labeled with DIGE fluorescent dyes. For this purpose we analyzed parasite samples taken at four-hour intervals from a tightly synchronized culture and established more than 500 individual protein abundance profiles with high temporal resolution and quantitative reproducibility. Approximately half of all profiles exhibit a significant change in abundance and 12% display an expression peak during the observed 12-hour time interval. Intriguingly, identification of 54 protein spots by mass spectrometry revealed that 58% of the corresponding proteins including actin-I, enolase, eIF4A, eIF5A, and several heat shock proteins are represented by more than one isoform, presumably due to post-translational modifications, with the various isoforms of a given protein frequently showing different expression patterns. Furthermore, comparisons with transcriptome data generated from the same parasite samples reveal significant post-transcriptional gene expression regulation. Conclusions: Together, our data indicate that both post-transcriptional and post-translational events are widespread and of presumably great biological significance during the intra-erythrocytic development of P. falciparum. Additional comment: In essence, the microarray data generated in this study is a repeat of the transcriptome analysis described in Bozdech et al., PLoS Biol 2003, 1(1):E5. Differences include (1) an improved set of oligonucleotides [see Hu et al., BMC Bioinformatics 2007, 8:350] used in the study associated with this GEO entry, and (2) the sampling at only four timepoints during the intra-erythrocytic development cycle (schizont stage) to match and complement the samples processed in the concomitant proteomics analysis. Four timepoint samples were harvested from a tightly synchronized 6 liter biofermenter culture of P. falciparum during schizont stage (at 34, 38, 42, and 46 hours post-invasion) and compared against a 3D7 RNA reference pool.

Project description:The pir genes comprise the largest multi-gene family in Plasmodium, with members found in P. vivax, P. knowlesi and the rodent malaria species. Despite comprising up to 5% of the parasite genome, little is known about the functions of the proteins encoded by pir genes. P. chabaudi causes chronic infection in mice, which may be due antigenic variation. In this model, pir genes are called cirs and may be involved in this mechanism allowing evasion of host immune responses. We have annotated the cir repertoire and performed detailed bioinformatic characterization of the encoded CIR proteins. Two major sub-families were identified: A and B, which display different amino acid motifs, and are thus predicted to have undergone functional divergence. The expression of all cirs was analyzed via RNA sequencing and microarray. Up to 40% of cir genes were expressed in the parasite population during infection, including members of both sub-families. Dominant cir transcripts could also be identified. Finally, specific cir genes were expressed at different time points during the blood stages of infection. Together our data characterizing the cir genes and their expression throughout the intra-erythrocytic cycle of development indicate that CIR proteins are likely to be important for parasite survival in the host. P. chabaudi AS is a highly synchronous parasite for which development in the blood follows its hostM-bM-^@M-^Ys circadian rhythm. Twelve time-points were then collected; one every two hours, to cover the entire 24 h cycle of blood stage development. At the peak of parasitaemia, one mouse was sacrificed at each time point and thin blood films were made and stained with Giemsa for optical microscopy. The pan-rodent microarray was designed using the OligoRankPick program as previously described: Liew, K et al.2010, Defining species specific genome differences in malaria parasites. BMC genomics 11,128. The RNA preparation, Cy-dye coupling to cDNA, hybridization and slide scanning were performed as described by Bozdech and colleagues Bozdech, Z et al 2003, The transcriptome of the intraerythrocytic developmental cycle of Plasmodium falciparum. PLoS Biol 1, E5.

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A crucial role of the zinc finger protein PfZnFP-G in sexual differentiation of the malaria parasites, Plasmodium falciparum

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