Characterisation of a new family of zinc finger proteins and their role in apicomplexan parasites' development and transmission.

The small parasites from the group called Apicomplexa are known to cause a number of human and animal diseases, including one of the most deadly infections in tropics - malaria. They are often being transmitted by the insect vectors and during their development go through a number of life forms of different appearance and function.

To progress through these complex life cycles, the parasites need to be able to switch on and off each of their genes in a timely and coordinated manner. Most of the commonly studied organisms are achieving this by using the proteins called transcription factors, which can act as molecular switches of the whole groups of genes. However only a very small number of them have been identified in the Apicomplexa, suggesting that their mechanisms of controlling the gene expression are significantly different.

The understanding of these mechanisms could open the way to new antiparasitic treatments but also allow better control of the parasites life cycles in laboratory conditions allowing the generation of a large number of desired life stages for the drug screening.

We have recently identified a group of parasite-specific proteins with the capacity to specifically bind the ribonucleic acids (RNA) - the key intermediates between the activated gene and its final product, whose stabilisation or degradation can be used to fine-tune the gene expression. These proteins are present in all Apicomplexa and their nearest relatives but not in any of the other organisms including the parasite hosts.

Importantly in the laboratory model of malaria infection, a number of them appear to be necessary for parasite's growth and infectivity. While these proteins may constitute a major group of Apicomplexa-specific gene regulators, the details of their role remain unknown.

The proposed project plans to investigate these proteins, understand the details of their function and identify the molecules/gene they are interacting with. In order to achieve this we plan to:

1) Study the evolution of these proteins, looking at the changes they underwent during the expansion of the Apicomplexa, mapping their similarities and differences between different species and comparing them to other protein families present in the parasites

2) In the model parasite (Plasmodium berghei) generate the mutants lacking each of the 11 proteins from the investigated family present in this species, and study the effects of these mutations on the parasite's ability to progress through its life cycle and control its RNA content

3) Choose 3-4 proteins, identified in the previous point as important for Plasmodium development, and study their function by a) identifying the RNA molecules they interact with (using three different complementary methods), b) studying the effects they have on the gene expression and c) discovering the proteins they interact with and mechanism by which the may degrade and/or stabilised their targets.

The combined data from the above investigations will provide a comprehensive picture of the role these newly identified proteins play in the gene expression regulation in malaria (and related parasites) and generate tools and avenues for their further investigation in multiple parasite species, potentially contributing to the new strategies of parasitic infections control.