Balaban Amanda E, Kanatani Sachie, Mitra Jaba, Gregory Jason, Vartak Natasha, Sinnis-Bourozikas Ariadne, Frischknecht Fredrich, Ha Taekjip, Sinnis Photini
Johns Hopkins Malaria Research Institute and Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21201, USA.
IDEXX Laboratories, Westbrook, ME, USA.
EMBO J. 2025 Sep 22. doi: 10.1038/s44318-025-00551-9.
The Plasmodium circumsporozoite protein (CSP) is the major surface protein of the sporozoite, the infective stage of the malaria parasite. The central repeat region of CSP is the primary immunological target of the sporozoite stage, yet little is known about its structure or function. Here, we show that sporozoite mutants with truncated or scrambled CSP repeats exhibit impaired motility due to altered adhesion site formation and dynamics. Since CSP forms the environment in which the thrombospondin-related anonymous protein (TRAP)-containing adhesion sites assemble, our data suggest that the dense CSP coat is altered in the repeat mutants, affecting adhesion site formation. We hypothesized that this role depends on the biophysical properties of the repeats, and used single-molecule fluorescence-force spectroscopy to test this hypothesis. Our results indicate that the CSP repeats behave like a stiff, linear spring with elastic properties that depend on its length and are lost when the repeats are scrambled. These data provide evidence for a functional role of the CSP repeat region during Plasmodium infection and motility.
疟原虫环子孢子蛋白（CSP）是疟原虫感染阶段即子孢子的主要表面蛋白。CSP的中央重复区域是子孢子阶段的主要免疫靶点，但对其结构或功能却知之甚少。在此，我们表明，具有截短或打乱的CSP重复序列的子孢子突变体由于粘附位点形成和动态变化而表现出运动能力受损。由于CSP形成了含血小板反应蛋白相关无名蛋白（TRAP）的粘附位点组装的环境，我们的数据表明，重复突变体中致密的CSP外壳发生了改变，影响了粘附位点的形成。我们推测这一作用取决于重复序列的生物物理特性，并使用单分子荧光力谱来验证这一假设。我们的结果表明，CSP重复序列的行为类似于一个刚性的线性弹簧，其弹性特性取决于其长度，当重复序列被打乱时弹性特性丧失。这些数据为CSP重复区域在疟原虫感染和运动过程中的功能作用提供了证据。
