Biol Open. 2013 Sep 16;2(11):1160-70. doi: 10.1242/bio.20136163.
Unique apicomplexan IMC sub-compartment proteins are early markers for apical polarity in the malaria parasite
Poulin B, Patzewitz EM, Brady D, Silvie O, Wright MH, Ferguson DJ, Wall RJ, Whipple S, Guttery DS, Tate EW, Wickstead B, Holder AA, Tewari R.
Centre for Genetics and Genomics, School of Life Sciences, Queens Medical Centre, University of Nottingham , Nottingham NG2 7UH , UK.
The phylum Apicomplexa comprises over 5000 intracellular protozoan parasites, including Plasmodium and Toxoplasma, that are clinically important pathogens affecting humans and livestock. Malaria parasites belonging to the genus Plasmodium possess a pellicle comprised of a plasmalemma and inner membrane complex (IMC), which is implicated in parasite motility and invasion. Using live cell imaging and reverse genetics in the rodent malaria model P. berghei, we localise two unique IMC sub-compartment proteins (ISPs) and examine their role in defining apical polarity during zygote (ookinete) development. We show that these proteins localise to the anterior apical end of the parasite where IMC organisation is initiated, and are expressed at all developmental stages, especially those that are invasive. Both ISP proteins are N-myristoylated, phosphorylated and membrane-bound. Gene disruption studies suggest that ISP1 is likely essential for parasite development, whereas ISP3 is not. However, an absence of ISP3 alters the apical localisation of ISP1 in all invasive stages including ookinetes and sporozoites, suggesting a coordinated function for these proteins in the organisation of apical polarity in the parasite.
ISP, Plasmodium, Polarity