Transcript maturation in apicomplexan parasites

Abstract

Summary The complex life cycles of apicomplexan parasites are associated with dynamic changes of protein repertoire. In Toxoplasma gondii, global analysis of gene expression demonstrates that dynamic changes in mRNA levels unfold in a serial cascade during asexual replication and up to 50% of encoded genes are unequally expressed in development. Recent studies indicate transcription as well as mRNA processing have important roles in fulfilling the “just-in-time” delivery of proteins to parasite growth and development. The prominence of post-transcriptional mechanisms in the Apicomplexa was demonstrated by mechanistic studies of the critical RNA-binding proteins and regulatory kinases. However, it is still early in our understanding of how transcription and post-transcriptional mechanisms are balanced to produce adequate numbers of specialized forms that is required to complete the parasite life cycle.

Cycling Transcriptional Networks Optimize Energy Utilization on a Genome Scale

“…Second, in addition to partitioning of cellular processes, in yeast (Bristow et al, 2014) and parasites (Bozdech et al, 2003; Suvorova and White, 2014) there is considerable gene expression turnover and gene expression occurs “as needed” in these organisms. In the yeast metabolic cycle, the three phases (Oxidative; Reductive, Building; Reductive, Charging) follow the strategy of “just-in-time” delivery of components (Kuang et al, 2014).…”

Multiple dimensions of epigenetic gene regulation in the malaria parasite Plasmodium falciparum

“…It would be interesting to fully characterize the epigenetic factors, such as genome architecture, that help PfAP2-G target and regulate gametocyte-specific genes. In addition to layers of epigenetic regulation that we have focused on here, posttranscriptional and translational controls are likely to be involved in the timing of protein expression [22][23][24]104]. Increased insight into these regulatory processes would significantly advance our understanding of parasite biology and could facilitate major breakthroughs in our fight against malaria.…”

“…Here, we focus on three important aspects of epigenetic gene regulation in P. falciparum, all of which are related to how DNA is packed in the nucleus (see [20][21][22][23][24] for articles discussing post-transcriptional regulation and see [25] for a discussion on DNA methylation, which is not wellcharacterized in P. falciparum). Similar to other eukaryotes, P. falciparum packages its DNA in the form of a condensed DNA-protein complex called chromatin.…”

Alternative Splicing in Apicomplexan Parasites

“…For example, Plasmodium spliceosomal RNAs (UsnRNAs) possess unusual 3′ poly(A) extensions (10), while several proteins normally involved in snRNA trafficking are apparently absent in apicomplexans (11), and some spliceosomal proteins contain divergent sequence features (12). Nonetheless, from what has been described thus far, the overall assembly, structure, and function of this apparatus closely reflects what is known from model eukaryotes, and we refer readers to a recent review for a survey of the general splicing machinery (9).…”

“…While some apicomplexan introns depart from the canonical TG-AG sites, the minor spliceosome appears to be absent in Apicomplexa, and indeed from Alveolata altogether (8). Recent work suggests that components of the apicomplexan U2-type spliceosome have acquired certain divergent features (9). For example, Plasmodium spliceosomal RNAs (UsnRNAs) possess unusual 3′ poly(A) extensions (10), while several proteins normally involved in snRNA trafficking are apparently absent in apicomplexans (11), and some spliceosomal proteins contain divergent sequence features (12).…”