Bandeira Paula Terra, Chaves Camila Rodrigues, Monteiro Torres Pedro Henrique, de Souza Wanderley
Laboratório de Ultraestrutura Celular Hertha Meyer, Centro de Pesquisa Em Medicina de Precisão, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil.
Laboratório de Modelagem E Dinâmica Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil.
Parasitol Res. 2025 Mar 7;124(3):30. doi: 10.1007/s00436-025-08466-4.
Nowadays, even in light of all the massive advances in cell biology, we still find some cellular structures that are not entirely understood. Among those, we highlight the costa, a structure from the mastigont system existent only in some members of the orders Trichomonadida and Tritrichomonadida, including the pathogens of venereal diseases in humans and cattle, Trichomonas vaginalis (T. vaginalis) and Tritrichomonas foetus (T. foetus), respectively. The costa is a prominent striated fiber and, although part of the cytoskeleton, differs from its classical components, and its molecular composition is still not fully characterized. Using proteomics of T. foetus's costa fraction, we previously identified hypothetic proteins, and among these, the protein ARM19800.1 positively localized in the costa and named costain-1. In this study, two other protein candidates were analyzed. To achieve the specific localization of 11810 and 32137 proteins in T. foetus's cells, it was used expansion microscopy and immunocytochemistry. The immunofluorescence revealed the presence of both proteins throughout the whole costa but with different intensities. Immunocytochemistry using negative staining, LR-White, and Epon embedding revealed further analyses of the protein's localization. All techniques confirmed the distinct and distributed localization of both proteins: costain-2 (11810) and costain-3 (32137). Also, AlfaFold3 was used to generate 3D models of the three identified proteins, showing a major prevalence of α-helical spans. Nonetheless, the identification and further characterization of these unique proteins can help understand their functional role in the assembled costa and, therefore, better understand the organization and function of this structure in these organisms.
如今，即使鉴于细胞生物学取得了所有巨大进展，我们仍然发现一些尚未完全被理解的细胞结构。其中，我们特别强调肋（costa），它是鞭毛基体系统中的一种结构，仅存在于毛滴虫目（Trichomonadida）和三毛滴虫目（Tritrichomonadida）的某些成员中，分别包括人类和牛的性病病原体阴道毛滴虫（Trichomonas vaginalis，T. vaginalis）和胎儿三毛滴虫（Tritrichomonas foetus，T. foetus）。肋是一种突出的横纹纤维，尽管是细胞骨架的一部分，但与经典成分不同，其分子组成仍未完全表征。利用胎儿三毛滴虫肋部分的蛋白质组学，我们先前鉴定出了假设蛋白，其中，蛋白ARM19800.1在肋中呈阳性定位，并被命名为肋蛋白-1（costain-1）。在本研究中，分析了另外两个蛋白质候选物。为了实现11810和32137这两种蛋白质在胎儿三毛滴虫细胞中的特异性定位，使用了扩展显微镜和免疫细胞化学技术。免疫荧光显示这两种蛋白质在整个肋中均有存在，但强度不同。使用负染色、LR-White和Epon包埋的免疫细胞化学揭示了对该蛋白质定位的进一步分析。所有技术均证实了这两种蛋白质——肋蛋白-2（11810）和肋蛋白-3（32137）的独特且分布的定位。此外，还使用AlfaFold3生成了这三种已鉴定蛋白质的三维模型，显示出α-螺旋跨度占主要比例。尽管如此，这些独特蛋白质的鉴定和进一步表征有助于了解它们在组装好的肋中的功能作用，从而更好地理解这些生物体中该结构的组织和功能。
