LPHI, UMR 5235, CNRS, INSERM, University of Montpellier, Montpellier, France.
Laboratory of Parasitology and Mycology, CNRS UMR 5290 MIVEGEC, University of Montpellier, Montpellier, France.
Cell Microbiol. 2021 Apr;23(4):e13303. doi: 10.1111/cmi.13303. Epub 2021 Jan 18.
Guanine-quadruplexes (G4s) are non-canonical DNA structures that can regulate key biological processes such as transcription, replication and telomere maintenance in several organisms including eukaryotes, prokaryotes and viruses. Recent reports have identified the presence of G4s within the AT-rich genome of Plasmodium falciparum, the protozoan parasite causing malaria. In Plasmodium, potential G4-forming sequences (G4FS) are enriched in the telomeric and sub-telomeric regions of the genome where they are associated with telomere maintenance and recombination events within virulence genes. However, there is a little understanding about the biological role of G4s and G4-binding proteins. Here, we provide the first snapshot of G4-interactome in P. falciparum using DNA pull-down assay followed by LC-MS/MS. Interestingly, we identified ~24 potential G4-binding proteins (G4-BP) that bind to a stable G4FS (AP2_G4). Furthermore, we characterised the role of G-strand binding protein 2 (PfGBP2), a putative telomere-binding protein in P. falciparum. We validated the interaction of PfGBP2 with G4 in vitro as well as in vivo. PfGBP2 is expressed throughout the intra-erythrocytic developmental cycle and is essential for the parasites in the presence of G4-stabilising ligand, pyridostatin. Gene knockout studies showed the role of PfGBP2 in the expression of var genes. Taken together, this study suggests that PfGBP2 is a bona fide G4-binding protein, which is likely to be involved in the regulation of G4-related functions in these malarial parasites. In addition, this study sheds light on this understudied G4 biology in P. falciparum.
鸟嘌呤四链体（G4s）是一种非经典的 DNA 结构，能够在包括真核生物、原核生物和病毒在内的多种生物中调节转录、复制和端粒维持等关键的生物学过程。最近的研究报告在引起疟疾的原生动物寄生虫疟原虫的富含 A-T 的基因组中发现了 G4s 的存在。在疟原虫中，潜在的 G4 形成序列（G4FS）在基因组的端粒和亚端粒区域富集，这些区域与端粒维持和毒力基因内的重组事件相关。然而，人们对 G4s 和 G4 结合蛋白的生物学作用知之甚少。在这里，我们使用 DNA 下拉测定法结合 LC-MS/MS 首次提供了 P. falciparum 中 G4 相互作用组的快照。有趣的是，我们鉴定了大约 24 个潜在的与稳定 G4FS（AP2_G4）结合的 G4 结合蛋白（G4-BP）。此外，我们还研究了疟原虫中的 G 链结合蛋白 2（PfGBP2）的作用，PfGBP2 是一种假定的端粒结合蛋白。我们在体外和体内验证了 PfGBP2 与 G4 的相互作用。PfGBP2 在整个红内期发育周期中表达，并在存在 G4 稳定配体吡啶斯的他汀时对寄生虫是必需的。基因敲除研究表明 PfGBP2 在 var 基因的表达中发挥作用。总之，这项研究表明 PfGBP2 是一种真正的 G4 结合蛋白，可能参与调节这些疟原虫中的 G4 相关功能。此外，这项研究揭示了在 P. falciparum 中这一研究较少的 G4 生物学。
