Park Esther, Mackens-Kiani Timur, Berhane Rebekah, Esser Hanna, Erdenebat Chimeg, Burroughs A Maxwell, Berninghausen Otto, Aravind L, Beckmann Roland, Green Rachel, Buskirk Allen R
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, United States.
Gene Center and Department of Biochemistry, University of Munich, Munich, Germany.
bioRxiv. 2023 May 6:2023.05.05.539626. doi: 10.1101/2023.05.05.539626.
Stalled ribosomes are rescued by pathways that recycle the ribosome and target the nascent polypeptide for degradation. In , these pathways are triggered by ribosome collisions through recruitment of SmrB, a nuclease that cleaves the mRNA. In , the related protein MutS2 was recently implicated in ribosome rescue. Here we show that MutS2 is recruited to collisions by its SMR and KOW domains and reveal the interaction of these domains with collided ribosomes by cryo-EM. Using a combination of and approaches, we show that MutS2 uses its ABC ATPase activity to split ribosomes, targeting the nascent peptide for degradation by the ribosome quality control pathway. Notably, we see no evidence of mRNA cleavage by MutS2, nor does it promote ribosome rescue by tmRNA as SmrB cleavage does in . These findings clarify the biochemical and cellular roles of MutS2 in ribosome rescue in and raise questions about how these pathways function differently in various bacteria.
停滞的核糖体通过回收核糖体并将新生多肽靶向降解的途径得以拯救。在[具体细菌名称1]中，这些途径由核糖体碰撞触发，通过招募SmrB（一种切割mRNA的核酸酶）来实现。在[具体细菌名称2]中，相关蛋白MutS2最近被认为参与核糖体拯救。在这里，我们表明MutS2通过其SMR和KOW结构域被招募到碰撞位点，并通过冷冻电镜揭示了这些结构域与碰撞核糖体的相互作用。使用[具体方法1]和[具体方法2]相结合的方法，我们表明MutS2利用其ABC ATPase活性来裂解核糖体，将新生肽靶向通过核糖体质量控制途径进行降解。值得注意的是，我们没有发现MutS2切割mRNA的证据，它也不像[具体细菌名称1]中的SmrB切割那样通过tmRNA促进核糖体拯救。这些发现阐明了MutS2在[具体细菌名称2]核糖体拯救中的生化和细胞作用，并引发了关于这些途径在各种细菌中如何不同发挥作用的问题。
