Gonçalves Camila Silva, Catta-Preta Carolina Moura Costa, Repolês Bruno Marçal, Ferreira Wesley Roger Rodrigues, Morini Flavia Souza, Mottram Jeremy C, Cavalcanti Danielle Pereira, de Souza Wanderley, Fragoso Stenio Perdigão, Machado Carlos Renato, Motta Maria Cristina M
Laboratório de Ultraestrutura Celular Hertha Meyer, Centro de Pesquisa em Medicina de Precisão (CPMP), Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, CEP 21941-590, Brazil.
Centro Nacional de Biologia Estrutural e Bioimagem - CENABIO, Rio de Janeiro, RJ, Brazil.
Parasit Vectors. 2025 Aug 28;18(1):366. doi: 10.1186/s13071-025-06985-8.
One of the most intriguing and unusual features of trypanosomatids is their mitochondrial DNA, known as kinetoplast DNA (kDNA), which is organized into a network of concatenated circles. The kDNA is contained within the mitochondrial matrix and can exhibit distinct arrangements across different species and during cell differentiation. In addition to kDNA, the kinetoplast contains multiple proteins, including those involved in mitochondrial DNA topology and metabolism, such as the kinetoplast-associated proteins (KAPs). In this work, we obtained mutant cells to investigates the role of KAP7 in two trypanosomatid species, Trypanosoma cruzi and Angomonas deanei, which have distinct kinetoplast shapes and kDNA arrangements.
For this purpose, the kDNA replication process and cell morphology and ultrastructure were evaluated using microscopy methods. Furthermore, the proliferation of cells treated with genotoxic agents, such as cisplatin and ultraviolet radiation, was analyzed.
In A. deanei, which contains a symbiotic bacterium, KAP7 seems to be essential, since the deletion of one KAP7 allele generated mutants with a decay in cell proliferation, as well as changes in kDNA structure and replication. In T. cruzi, null mutants exhibited disturbances in kDNA replication, although the overall topology remained unaltered. The use of cisplatin and ultraviolet (UV) radiation affected the ultrastructure of A. deanei and T. cruzi. Cisplatin promoted increased kDNA compaction in both KAP7 mutants, but only in T. cruzi did the proliferative capacity fail to recover after treatment, as was also observed following UV radiation exposure.
Proteins associated with DNA are evolutionarily conserved and usually perform similar functions in different organisms. Our findings reveal that KAP7 is involved in kDNA replication, but its roles differ in trypanosomatid species: in A. deanei, KAP7 is associated with kDNA arrangement, while in T. cruzi, it is related to mitochondrial metabolism, such as kDNA replication and damage response.
锥虫最引人入胜且独特的特征之一是其线粒体DNA，即动质体DNA（kDNA），它被组织成一个由连环环组成的网络。kDNA包含在线粒体基质中，在不同物种以及细胞分化过程中可呈现出不同的排列方式。除了kDNA，动质体还包含多种蛋白质，包括那些参与线粒体DNA拓扑结构和代谢的蛋白质，如动质体相关蛋白（KAPs）。在这项研究中，我们获得了突变细胞，以研究KAP7在两种锥虫（克氏锥虫和德氏按蚊锥虫）中的作用，这两种锥虫具有不同的动质体形状和kDNA排列方式。
为此，使用显微镜方法评估kDNA复制过程以及细胞形态和超微结构。此外，分析了用顺铂和紫外线等基因毒性剂处理的细胞的增殖情况。
在含有共生细菌的德氏按蚊锥虫中，KAP7似乎是必不可少的，因为删除一个KAP7等位基因会产生细胞增殖衰退以及kDNA结构和复制发生变化的突变体。在克氏锥虫中，缺失突变体在kDNA复制方面表现出紊乱，尽管整体拓扑结构保持不变。顺铂和紫外线（UV）辐射的使用影响了德氏按蚊锥虫和克氏锥虫的超微结构。顺铂促使两种KAP7突变体中的kDNA压缩增加，但只有在克氏锥虫中，处理后增殖能力未能恢复，紫外线辐射暴露后也观察到了这种情况。
与DNA相关的蛋白质在进化上是保守的，通常在不同生物体中执行相似的功能。我们的研究结果表明，KAP7参与kDNA复制，但其在锥虫物种中的作用有所不同：在德氏按蚊锥虫中，KAP7与kDNA排列有关，而在克氏锥虫中，它与线粒体代谢有关，如kDNA复制和损伤反应。
