Abstract
Ubiquitination tags proteins for different functions within the cell. One of the most abundant and studied ubiquitin modification is the Lys48 polyubiquitin chain that modifies proteins for their destruction by proteasome. In Plasmodium is proposed that post-translational regulation is fundamental for parasite development during its complex life-cycle; thus, the objective of this work was to analyze the ubiquitination during Plasmodium chabaudi intraerythrocytic stages. Ubiquitinated proteins were detected during intraerythrocytic stages of Plasmodium chabaudi by immunofluorescent microscopy, bidimensional electrophoresis (2-DE) combined with immunoblotting and mass spectrometry. All the studied stages presented protein ubiquitination and Lys48 polyubiquitination with more abundance during the schizont stage. Three ubiquitinated proteins were identified for rings, five for trophozoites and twenty for schizonts. Only proteins detected with a specific anti- Lys48 polyubiquitin antibody were selected for Mass Spectrometry analysis and two of these identified proteins were selected in order to detect the specific amino acid residues where ubiquitin is placed. Ubiquitinated proteins during the ring and trophozoite stages were related with the invasion process and in schizont proteins were related with nucleic acid metabolism, glycolysis and protein biosynthesis. Most of the ubiquitin detection was during the schizont stage and the Lys48 polyubiquitination during this stage was related to proteins that are expected to be abundant during the trophozoite stage. The evidence that these Lys48 polyubiquitinated proteins are tagged for destruction by the proteasome complex suggests that this type of post-translational modification is important in the regulation of protein abundance during the life-cycle and may also contribute to the parasite cell-cycle progression.
Highlights
Malaria is a mosquito-borne disease caused by members of the genus Plasmodium and it was responsible for ~300 million cases and ~580,000 deaths in 2014 [1]
P. chabaudi ubiquitin protein is predicted to be the product of two ubiquitin fusion genes, UBS27a [PlasmoDB:PCHAS_104020] and UBL40 [PlasmoDB:PCHAS_114120], that encode a single copy of ubiquitin fused to the ribosomal protein S27a and L40, respectively, and the polyubiquitin gene [PlasmoDB:PCHAS_061200] (Fig 1A)
The open reading frame (ORF) of the polyubiquitin gene encodes a pro-protein of 305 aa in length comprising four 76 aa tandem repeats with an extra amino acid residue in the last repeat probably processed by a deubiquitinating enzyme as occurs in Nedd8 where the C-terminal is processed by NEDP1 or UCHL3 [34]
Summary
Malaria is a mosquito-borne disease caused by members of the genus Plasmodium and it was responsible for ~300 million cases and ~580,000 deaths in 2014 [1]. One of the main purposes of understanding the biology of these parasites is to interrupt at least one of the replicative stages within its complicated life-cycle. Plasmodium chabaudi exhibits a synchronous intraerythrocytic cycle and other genetic and biology features that make it suitable for experimentation due to the extensive similarities between the infected mice and human infection mainly with P. falciparum [3]. The complete life-cycle of malaria parasites includes three main developmental stages, one takes place in the vector mosquito, and two in the vertebrate host in the liver and red blood cells. The latter is concluded within 48 and 24 h in P. falciparum and P. chabaudi, respectively, after a schizogonic process [3]. Ubiquitination, the binding of ubiquitin (Ub) units to proteins, is a major player that participates in the regulation of protein degradation, intracellular trafficking, DNA repair, cell cycle, cell differentiation, signal transduction and immune responses [5, 12,13,14,15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
