Dipartimento di Malattie Infettive, Parassitarie e Immunomediate, Istituto Superiore di Sanità, Viale Regina Elena n.299, 00161 Rome, Italy.
Int J Parasitol. 2010 May;40(6):663-73. doi: 10.1016/j.ijpara.2009.11.006. Epub 2009 Dec 5.
Gametocytes of the protozoan Plasmodium falciparum ensure malaria parasite transmission from humans to the insect vectors. In their development, they produce the abundant specific protein Pfg27, the function and in vivo molecular interactions of which are unknown. Here we reveal a previously unreported localisation of Pfg27 in the gametocyte nucleus by immunoelectron microscopy and studies with HaloTag and Green Fluorescent Protein fusions, and identify a network of interactions established by the protein during gametocyte development. We report the ability of endogenous Pfg27 to form oligomeric complexes that are affected by phosphorylation of the protein, possibly through the identified phosphorylation sites, Ser32 and Thr208. We show that Pfg27 binds RNA molecules through specific residues and that the protein interacts with parasite RNA-binding proteins such as EF1alpha and PfH45. We propose a structural model for Pfg27 oligomerisation, based on the sequence and structural conservation here recognised between Pfg27 and sterile alpha motif. This study provides a molecular basis for Pfg27 to establish an interaction network with RNA and RNA-binding proteins and to govern its dynamic oligomerisation in developing gametocytes.
疟原虫配子体保证了疟原虫从人类到昆虫媒介的传播。在发育过程中，它们产生丰富的特异性蛋白 Pfg27，但该蛋白的功能和体内分子相互作用尚不清楚。本文通过免疫电子显微镜和 HaloTag 和绿色荧光蛋白融合研究，揭示了 Pfg27 在配子体核内的一个以前未报道的定位，并鉴定了该蛋白在配子体发育过程中建立的相互作用网络。我们报告了内源性 Pfg27 形成寡聚体复合物的能力，该能力受到蛋白磷酸化的影响，可能是通过已鉴定的磷酸化位点 Ser32 和 Thr208。我们表明 Pfg27 通过特定残基结合 RNA 分子，并且该蛋白与寄生虫 RNA 结合蛋白（如 EF1alpha 和 PfH45）相互作用。我们基于在此识别到的 Pfg27 和 sterile alpha motif 之间的序列和结构保守性，提出了 Pfg27 寡聚化的结构模型。这项研究为 Pfg27 与 RNA 和 RNA 结合蛋白建立相互作用网络，并控制其在发育中的配子体中的动态寡聚化提供了分子基础。
