Comparative Analysis of Apicomplexa and Genomic Diversity in Eukaryotes

Abstract

The apicomplexans Plasmodium and Cryptosporidium have developed distinctive adaptations via lineage-specific gene loss and gene innovation in the process of diverging from a common parasitic ancestor. The two lineages have acquired distinct but overlapping sets of surface protein adhesion domains typical of animal proteins, but in no case do they share multidomain architectures identical to animals. Cryptosporidium, but not Plasmodium, possesses an animal-type O-linked glycosylation pathway, along with >30 predicted surface proteins having mucin-like segments. The two parasites have notable qualitative differences in conserved protein architectures associated with chromatin dynamics and transcription. Cryptosporidium shows considerable reduction in the number of introns and a concomitant loss of spliceosomal machinery components. We also describe additional molecular characteristics distinguishing Apicomplexa from other eukaryotes for which complete genome sequences are available

Diversity of extracellular proteins during the transition from the ‘proto-apicomplexan’ alveolates to the apicomplexan obligate parasites

“…Annotation of chromerids and colpodellids also reveals mucin proteins (for example Cvel_819. t1, Cvel_541.t1, and Colpodella_angusta_Spi-2_ cDNA_ca@a28207_52), as well as a conserved O-linked glycosylation machinery which was first described in coccidians (Templeton et al 2004b;Walker et al 2010). Our rough annotation of P. marinus indicates that it has perhaps an order of magnitude more genes which encode predicted mucins than Chromera, with potentially over 500 mucin genes within several families; based upon the features of predicted secretion, the presence of threonine repeats, and transmembrane or GPI-anchor domains.…”

“…For example, component domains of the multi-domain CCP/LAP proteins (namely, ricin, NEC, SR, LCCL, as well as other domains) also have a phylogenetic distribution uniting the chromerids with Apicomplexa, to the exclusion of Perkinsus and the ciliates. Many of the extracellular domains common to chromerids and Apicomplexa are also found in metazoans, and thereby may have arisen through lateral transfer (Templeton et al 2004b;Aravind et al 2012). Table 2 illustrates the variety of domains and multi-domain architecture expansions, using chromerids as examples.…”

High Mobility Group Protein HMGB2 Is a Critical Regulator of Plasmodium Oocyst Development

“…Nevertheless, the other down-regulated genes could contribute to ookinete and oocyst formation given their protein expression profile and conservation across Plasmodium species. For example three gametocyte-specific articulins, a class of cytoskeletal proteins, are down-regulated in the ⌬pyhmgb2 parasites suggesting involvement of articulins in the maintenance of stagespecific cellular shapes (35).…”

Whole-genome analysis reveals molecular innovations and evolutionary transitions in chromalveolate species

“…Despite general shared features, the alveolates have greatly diverged in many respects, including host specificities, tissue tropisms, and the requirement of multiple hosts (4). The obligate intracellular apicomplexans contain several protozoan pathogens that provoke severe diseases in mammals, including humans.…”