School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.
Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
Nat Commun. 2023 Jan 18;14(1):300. doi: 10.1038/s41467-023-35914-5.
Historically, ribosomes were viewed as unchanged homogeneous macromolecular machines with no regulatory capacity for mRNA translation. An emerging concept is that heterogeneity of ribosomal composition exists, exerting a regulatory function or specificity in translational control. This is supported by recent discoveries identifying compositionally distinct specialised ribosomes that actively regulate mRNA translation. Viruses lack their own translational machinery and impose high translational demands on the host during replication. We explore the possibility that KSHV manipulates ribosome biogenesis producing specialised ribosomes which preferentially translate viral transcripts. Quantitative proteomic analysis identified changes in the stoichiometry and composition of precursor ribosomal complexes during the switch from latent to lytic replication. We demonstrate the enhanced association of ribosomal biogenesis factors BUD23 and NOC4L, and the KSHV ORF11 protein, with small ribosomal subunit precursor complexes during lytic replication. BUD23 depletion resulted in significantly reduced viral gene expression, culminating in dramatic reduction of infectious virion production. Ribosome profiling demonstrated BUD23 is essential for reduced association of ribosomes with KSHV uORFs in late lytic genes, required for the efficient translation of the downstream coding sequence. Results provide mechanistic insights into KSHV-mediated manipulation of cellular ribosome composition inducing a population of specialised ribosomes facilitating efficient translation of viral mRNAs.
从历史上看，核糖体被视为不变的同质性大分子机器，没有调节 mRNA 翻译的能力。一个新兴的概念是，核糖体组成存在异质性，在翻译调控中发挥调节功能或特异性。这一概念得到了最近的发现的支持，这些发现确定了组成上不同的专门核糖体，它们积极调节 mRNA 翻译。病毒缺乏自己的翻译机制，并在复制过程中对宿主施加高翻译需求。我们探讨了 KSHV 操纵核糖体生物发生产生专门核糖体的可能性，这些核糖体优先翻译病毒转录本。定量蛋白质组学分析在潜伏到裂解复制的转换过程中，鉴定了前核糖体复合物的计量和组成的变化。我们证明了核糖体生物发生因子 BUD23 和 NOC4L 以及 KSHV ORF11 蛋白与小核糖体亚基前体复合物在裂解复制过程中的增强关联。BUD23 的耗竭导致病毒基因表达显著降低，最终导致传染性病毒粒子的产生显著减少。核糖体谱分析表明，BUD23 对于减少晚期裂解基因中核糖体与 KSHV uORFs 的结合是必需的，这对于下游编码序列的有效翻译是必需的。结果为 KSHV 介导的细胞核糖体组成的操纵提供了机制上的见解，诱导了专门核糖体的群体，从而促进了病毒 mRNA 的高效翻译。
