Zhao Xiaojing, He Yixin, Zhang Fan, Aphasizheva Inna, Aphasizhev Ruslan, Zhang Liye
School of Life Science and Technology, ShanghaiTech University, Shanghai201210, China.
Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA 02118, United States.
Nucleic Acids Res. 2025 Jul 8;53(13). doi: 10.1093/nar/gkaf661.
Trypanosoma brucei, a kinetoplastid parasite, cycles between a tsetse fly vector and a mammalian host, undergoing profound changes in cell architecture and metabolism. Central to these transitions are modifications in mitochondrial structure, volume, and energy production. The parasite's mitochondrial genome is highly complex, comprising a few maxicircles that encode proteins and rRNAs, and thousands of minicircles that encode guide RNAs (gRNAs). Most messenger RNAs (mRNAs) sustain gRNA-directed U-insertion/deletion editing to acquire functional protein-coding sequences. Although the minicircle repertoire varies among isolates and environmental conditions, the extent and biological significance of this variability in commonly used laboratory strains remain unclear. Here, we analyzed mitochondrial genomes and transcriptomes of the developmentally competent AnTat1.1 strain, the differentiation-incapable Lister 427 strain, and transgenic derivatives of Lister 427. While maxicircle sequences are broadly conserved and stable, minicircles differ markedly in sequence complexity, relative abundance, and gRNA gene content. These variations likely affect the efficiency and accuracy of mRNA editing. Compared with Lister 427, the AnTat1.1 strain retains greater minicircle diversity, longer predicted gRNA-mRNA duplexes, and higher editing fidelity. By examining cell lines with distinct developmental capacities and cultivation histories, our findings reveal how mitochondrial genomes evolve in response to changing environmental contexts.
布氏锥虫是一种动基体寄生虫，在采采蝇载体和哺乳动物宿主之间循环，细胞结构和代谢会发生深刻变化。这些转变的核心是线粒体结构、体积和能量产生的改变。该寄生虫的线粒体基因组高度复杂，由几个编码蛋白质和rRNA的大环状DNA以及数千个编码引导RNA（gRNA）的小环状DNA组成。大多数信使RNA（mRNA）进行gRNA指导的U插入/缺失编辑以获得功能性蛋白质编码序列。尽管小环状DNA的组成在不同分离株和环境条件下有所不同，但常用实验室菌株中这种变异性的程度和生物学意义仍不清楚。在这里，我们分析了具有发育能力的AnTat1.1菌株、无分化能力的利斯特427菌株以及利斯特427的转基因衍生物的线粒体基因组和转录组。虽然大环状DNA序列广泛保守且稳定，但小环状DNA在序列复杂性、相对丰度和gRNA基因含量方面存在显著差异。这些变异可能会影响mRNA编辑的效率和准确性。与利斯特427相比，AnTat1.1菌株保留了更大的小环状DNA多样性、更长的预测gRNA-mRNA双链体和更高的编辑保真度。通过检查具有不同发育能力和培养历史的细胞系，我们的研究结果揭示了线粒体基因组如何响应不断变化的环境背景而进化。
