DOC2 whole genome sequencing study

We report the discovery of DOC2.1 and its conserved role in Ca2 -mediated control of microneme exocytosis across the Apicomplexa. DOC2.1 was identified with whole-genome mutational profiling (WGMP), an approach combining chemical mutagenesis and phenotypic screening with deep organismal sequencing. DOC2.1 contained the etiological point mutation in a temperature sensitive Toxoplasma gondii egress mutant with a defect in Ca2 -dependent microneme secretion, required for both host cell invasion and egress. A conditional allele of the orthologous gene in Plasmodium falciparum resulted in a comparable phenotype, demonstrating the conserved role of DOC2.1. Since DOC2 proteins are Ca2 -dependent proteins that recruit the membrane fusion machinery required for vesicle release, these results substantially expand the mechanistic understanding of microneme secretion, a critical process in toxoplasmosis and malaria.