Arrest of Nuclear Division in Plasmodium through Blockage of Erythrocyte Surface Exposed Ribosomal Protein P2

Sudipta Das,Himanish Basu,Shobhona Sharma,Rita Tewari,Reshma Korde,Joe Smith

doi:10.1371/journal.ppat.1002858

Sudipta Das, Himanish Basu + Show 4 more

Open Access

https://doi.org/10.1371/journal.ppat.1002858

Copy DOI

Abstract

Malaria parasites reside inside erythrocytes and the disease manifestations are linked to the growth inside infected erythrocytes (IE). The growth of the parasite is mostly confined to the trophozoite stage during which nuclear division occurs followed by the formation of cell bodies (schizogony). The mechanism and regulation of schizogony are poorly understood. Here we show a novel role for a Plasmodium falciparum 60S stalk ribosomal acidic protein P2 (PfP2) (PFC0400w), which gets exported to the IE surface for 6–8 hrs during early schizogony, starting around 26–28 hrs post-merozoite invasion. The surface exposure is demonstrated using multiple PfP2-specific monoclonal antibodies, and is confirmed through transfection using PfP2-GFP. The IE surface-exposed PfP2-protein occurs mainly as SDS-resistant P2-homo-tetramers. Treatment with anti-PfP2 monoclonals causes arrest of IEs at the first nuclear division. Upon removal of the antibodies, about 80–85% of synchronized parasites can be released even after 24 hrs of antibody treatment. It has been reported that a tubovesicular network (TVN) is set up in early trophozoites which is used for nutrient import. Anti-P2 monoclonal antibodies cause a complete fragmentation of TVN by 36 hrs, and impairs lipid import in IEs. These may be downstream causes for the cell-cycle arrest. Upon antibody removal, the TVN is reconstituted, and the cell division progresses. Each of the above properties is observed in the rodent malaria parasite species P. yoelii and P. berghei. The translocation of the P2 protein to the IE surface is therefore likely to be of fundamental importance in Plasmodium cell division.

Highlights

Malaria, caused by the species Plasmodium, is a prevalent tropical infectious disease, which continues to take a large toll on lives (WHO guidelines, 2008)
AntiP2 monoclonal antibodies (mAbs) E2G12 was specific for Plasmodium P2 protein and reacted with the 27–49 amino-acids peptide (Figure 1BIII) while A12D9 mapped to the 92–112 amino acids extreme-Cterminal region of P2 (Figure 1BI, Cc)
The rabbit polyclonal anti-PfP1 antibody reacted with both PfP1 and PfP2 in denatured conditions (Figure 1DII), it did not react to recombinant PfP2 under native conditions (Figure 1BII)

Summary

Introduction

Malaria, caused by the species Plasmodium, is a prevalent tropical infectious disease, which continues to take a large toll on lives (WHO guidelines, 2008). Cell division in Plasmodium occurs largely through a schizogonic process, in which the nuclei divide asynchronously at first into about 16–24 nuclei, followed by the formation of cell bodies [1,2,3,4,5]. Certain filament forming fungal species form multinuclear hyphal compartments, in which the nuclear position and cell cycle is only loosely coordinated with septum placement [8,9]. This type of nuclear division might enable cells to spatially restrict mitoses within a shared cytoplasm, potentially facilitating local responses to nutrients or other environmental stimuli

Methods

Results

Discussion

Conclusion