An iron lens for translational regulation in Toxoplasma gondii

Apicomplexan parasite Toxoplasma gondii’s ability to sense and regulate iron levels is critical to its ability to cause disease. Yet, little is known about how these parasites coordinate responses to the dynamic iron environment in their hosts. Translational regulation, mediated by mRNA-binding proteins (mRBPs), of iron acquisition/storage proteins appears conserved across the tree of life. As such, I propose to investigate the role mRNA-binding proteins in regulating T. gondii iron content. Many organisms use aconitase to regulate cellular iron. Under iron starvation, aconitase binds short sequences in mRNAs, called iron response elements (IREs), regulating translation according to IRE position. Using genetic techniques, I will determine whether T. gondii uses aconitase/IREs to regulate iron content. Other, less conserved, mRBPs have been implicated in iron homeostasis in other model organisms. To identify novel post-transcriptional regulators of T. gondii iron homeostasis, I will characterise all mRNA-protein complexes whose abundance changes according to iron availability using enhanced RNA-interactome capture. I will use genetic techniques to validate and characterise iron-responsive mRBPs. To uncover how shortlisted mRBPs regulate cellular iron, I will identify their target transcripts using immunoprecipitation and RNA-sequencing. Using molecular techniques, I will determine the consequences of mRBP-binding on transcript stability, localisation, and translation.