Function of Actins in Malaria Parasites

Two different patterns of Actin II (magenta) expression in Plasmodium sexual cells, nucleus in blue

Actins have prominent roles in the malaria parasite and two actin isoforms, which are both divergent from actin of higher eukaryotes and from each other, are present. Actin I is ubiquitously found in all stages of the parasite, and has an important role in cell motility and invasion.
Actin II is expressed only in the mosquito stages. The protein has two functions, unrelated to motility: during male gametogenesis and during the zygote stage. The function at the molecular level is not yet completely understood for either of the two actins but our studies have revealed that the functions of the two actins are not equivalent in vivo. Our present work focuses on the role of an actin-binding protein called C-CAP (cyclase associated protein), that is essential for oocyst development. We have analyzed the expression of the protein showing that C-CAP is only expressed in the sexual stages and the ookinete. Furthermore, we have identified interacting proteins confirming that C-CAP binds actin I.

References:
Deligianni et al. (2011) Critical role for a stage-specific actin in male exflagellation of the malaria parasite. Cell Microbiol. 13:1714-1730

Siden-Kiamos et al. (2012). Evidence for filamentous actin in ookinetes of a malarial parasite. Mol. Biochem. Parasitol. 181(2):186-9

Andreadaki et al. (2014) Genetic crosses and complementation reveal essential functions for the Plasmodium stage-specific actin2 in sporogonic development. Cell. Microbiol. 16(5):751-67. doi: 10.1111/cmi.12274

Vahokoski et al. (2014) Structural Differences Explain Diverse Functions of Plasmodium Actins. PLoS Pathog. Apr 17;10(4):e1004091. doi: 10.1371/journal.ppat.1004091.

Hliscs et a. (2014) Organisation and function of an actin cytoskeleton in Plasmodium falciparum gametocytes. Cell. Microbiol, 2014 Sep 16. doi: 10.1111/cmi.12359.

Andreadaki et al. (2015) Global expression profiling reveals shared and distinct transcript signatures in arrested act2(-) and CDPK4(-) Plasmodium berghei gametocytes.Mol Biochem Parasitol. 2015 Jun;201(2):100-7. doi: 10.1016/j.molbiopara.2015.07.001.

Maria Andreadaki et al. (2016) Expression of the Plasmodium berghei actin II gene is controlled by elements in a long genomic region Parasitology Research 115(8):3261-5. doi: 10.1007/s00436-016-5133-z.

Curra et al. (2017) Structured illumination microscopy reveals actin I localization in discreet foci in Plasmodium berghei gametocytes.Exp Parasitol. 2017 Oct;181:82-87. doi: 10.1016/j.exppara.2017.08.001.

Lopez et al. (2023). Structure and function of Plasmodium actin II in the parasite mosquito stages. PLoS Pathog. 2023 Mar 6;19(3):e1011174. doi: 10.1371/journal.ppat.1011174.