Plasmodium falciparum GBP2 Is a Telomere-Associated Protein That Binds to G-Quadruplex DNA and RNA

Abstract

<jats:p>In the early-diverging protozoan parasite <jats:italic>Plasmodium</jats:italic>, few telomere-binding proteins have been identified and several are unique. <jats:italic>Plasmodium</jats:italic> telomeres, like those of most eukaryotes, contain guanine-rich repeats that can form G-quadruplex structures. In model systems, quadruplex-binding drugs can disrupt telomere maintenance and some quadruplex-binding drugs are potent anti-plasmodial agents. Therefore, telomere-interacting and quadruplex-interacting proteins may offer new targets for anti-malarial therapy. Here, we report that <jats:italic>P. falciparum</jats:italic> GBP2 is such a protein. It was identified <jats:italic>via</jats:italic> ‘Proteomics of Isolated Chromatin fragments’, applied here for the first time in <jats:italic>Plasmodium</jats:italic>. <jats:italic>In vitro</jats:italic>, <jats:italic>Pf</jats:italic>GBP2 binds specifically to G-rich telomere repeats in quadruplex form and it can also bind to G-rich RNA. <jats:italic>In vivo</jats:italic>, <jats:italic>Pf</jats:italic>GBP2 partially colocalises with the known telomeric protein HP1 but is also found in the cytoplasm, probably due to its affinity for RNA. Consistently, its interactome includes numerous RNA-associated proteins. <jats:italic>Pf</jats:italic>GBP2 is evidently a multifunctional DNA/RNA-binding factor in <jats:italic>Plasmodium</jats:italic>.</jats:p>