Role of two histone-fold domain proteins in Plasmodium parasites

• Grant number: 16/22451-2
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: April 01, 2017
• End date: June 30, 2017
• Field of knowledge: Biological Sciences - Parasitology - Protozoology of Parasites
• Principal Investigator: Célia Regina da Silva Garcia
• Grantee: Chiara Currà
• Supervisor: Inga Siden-Kiamos
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Foundation for Research and Technology-Hellas (FORTH), Greece
• Associated to the scholarship: 16/03952-0 - Role of two histone-fold domain proteins in Plasmodium parasites, BP.PD

Abstract

The histone-fold domain (HFD) is found in histones of eukaryotes and Archaea, but also in a family of proteins involved in transcriptional regulation, the so called NF-Y family. NF-Y is composed of three subunits: NF-YA, NF-YB and NF-YC. The B and C subunits each contains a HFD, and these two subunits form a tight dimer through the interaction of these domains. As a dimer they bind to DNA non-specifically, while the A subunit binds DNA with sequence specificity upon interaction with the dimer. Two proteins of Plasmodium parasites ORP1 (Oocyst Rupture Protein1), also annotated as NF-YB, and ORP2, containing a similar HFD to NF-YC are probably not bona fide NFY subunits. The reason is i) no orthologue of the NF-YA subunit exist in Plasmodium, which rules out the role of NF-YB/C as subunits of a transcription factor NF-Y complex -like; ii) ORPs are much bigger than NFY subunits. In Curr et al. (Nat Comm 2016) we showed that ORPs have divergent functions in Plasmodium, being the dimerization of the HFDs a fundamental step in the transmission of the parasite. In fact, mutant parasites lacking either one of the orp, are blocked at oocysts stage, since sporozoites are formed but egress from oocyst is blocked. Furthermore, mutant orp(-) sporozoites are not able to establish infection in the vertebrate host. Within this BEPE project, I will continue my collaborations with Dr Inga Siden-Kiamos lab in Greece having the opportunity to develop my project and infect An gambiae mosquitoes with my different mutants containing partial deletion of the ORP proteins and a fluorescent tag, as mentioned in my general FAPESP project. I will aim to show the direct role of ORP1-2 HFDs dimerization during oocyst rupture using new mutant lines generated under FAPESP project. Reverse genetic and biochemistry approaches will be used as appropriate, and international collaborations will implement the feasibility of this project. Excellent results, new tasks and knowledge will contribute to progress of malaria transmission blocking strategies. The exploit of HFDs in divergent functions outside transcription is a very innovative finding in Plasmodium and new targets for drug/vaccine development can be identified. The collaboration with Siden-Kiamos lab in Greece was already mentioned in my proposal for the FAPESP fellowship in Brazil. (AU)