Elahi Rubayet, Dinis Luciana Ribeiro, Swift Russell P, Liu Hans B, Prigge Sean T
Department of Molecular Microbiology and Immunology, Johns Hopkins University, Baltimore, Maryland, USA.
The Johns Hopkins Malaria Research Institute, Baltimore, Maryland, USA.
bioRxiv. 2025 Jan 6:2024.12.21.629855. doi: 10.1101/2024.12.21.629855.
The circular genome of the apicoplast contains a complete minimal set of tRNAs, positioning the apicoplast as an ideal model for studying the fundamental factors required for protein translation. Modifications at tRNA wobble base positions, such as xmsU, are critical for accurate protein translation. These modifications are ubiquitously found in tRNAs decoding two-family box codons ending in A or G in prokaryotes and in eukaryotic organelles. Here, we investigated the xmsU biosynthetic pathway in the apicoplast organelle of . Through comparative genomics, we identified orthologs of enzymes involved in this process: SufS, MnmA, MnmE, and MnmG. While SufS and MnmA were previously shown to catalyze sU modifications, we now show that MnmE and MnmG are apicoplast-localized and contain features required for xmsU biosynthetic activity. Notably, we found that lacks orthologs of MnmC, MnmL, and MnmM, suggesting that the parasites contain a minimal xmsU biosynthetic pathway similar to that found in bacteria with reduced genomes. Deletion of either MnmE or MnmG resulted in apicoplast disruption and parasite death, mimicking the phenotype observed in Δ and Δ parasites. Our data strongly support the presence and essentiality of xmsU modifications in apicoplast tRNAs. This study advances our understanding of the minimal requirements for protein translation in the apicoplast organelle.
顶质体的环状基因组包含一套完整的最小tRNA集合，这使得顶质体成为研究蛋白质翻译所需基本要素的理想模型。tRNA摆动碱基位置的修饰，如xmsU，对于准确的蛋白质翻译至关重要。这些修饰普遍存在于原核生物和真核细胞器中解码以A或G结尾的双家族框密码子的tRNA中。在这里，我们研究了[具体物种]顶质体细胞器中的xmsU生物合成途径。通过比较基因组学，我们鉴定出了参与这一过程的酶的直系同源物：SufS、MnmA、MnmE和MnmG。虽然之前已证明SufS和MnmA催化sU修饰，但我们现在表明MnmE和MnmG定位于顶质体，并且具有xmsU生物合成活性所需的特征。值得注意的是，我们发现[具体物种]缺乏MnmC、MnmL和MnmM的直系同源物，这表明该寄生虫含有与基因组简化的细菌中相似的最小xmsU生物合成途径。删除MnmE或MnmG会导致顶质体破坏和寄生虫死亡，这与在Δ[相关基因缺失型寄生虫]和Δ[相关基因缺失型寄生虫]中观察到的表型相似。我们的数据有力地支持了顶质体tRNA中xmsU修饰的存在及其必要性。这项研究推进了我们对顶质体细胞器中蛋白质翻译最小要求的理解。
