Release factor-dependent ribosome rescue by BrfA in the Gram-positive bacterium Bacillus subtilis
Release factor-dependent ribosome rescue by BrfA in the Gram-positive bacterium Bacillus subtilis
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DOI：
10.1038/s41467-019-13408-7
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发表时间：
2019-11-27
影响因子：
16.6
通讯作者：
Chiba, Shinobu
中科院分区：
文献类型：
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作者：
Shimokawa-Chiba, Naomi;Mueller, Claudia;Chiba, Shinobu
从死端翻译复合物中拯救核糖体，如截短（非终止）mRNA上的核糖体，对细胞至关重要。尽管细菌使用反式翻译进行核糖体拯救，但一些革兰氏阴性菌具有替代性和释放因子（RF）依赖性拯救因子，其使得RF能够催化不依赖于终止密码子的多肽释放。我们现在发现革兰氏阳性枯草芽孢杆菌具有一种进化上独特的核糖体拯救因子，命名为BrfA。遗传分析表明，B.枯草芽孢杆菌的生长需要转译或BrfA的功能，即使在没有蛋白毒性应激的情况下。生化和冷冻电子显微镜（cryo-EM）表征表明，BrfA结合到不停止停滞的核糖体，招募同源RF 2，但不是RF 1，并诱导其转变成一个开放的活性构象。虽然BrfA与E. coliArfA，他们在作用模式和表达调控方面使用收敛策略，表明许多细菌可能已经进化出尚未鉴定的核糖体拯救系统。
Rescue of the ribosomes from dead-end translation complexes, such as those on truncated (non-stop) mRNA, is essential for the cell. Whereas bacteria use trans-translation for ribosome rescue, some Gram-negative species possess alternative and release factor (RF)-dependent rescue factors, which enable an RF to catalyze stop-codon-independent polypeptide release. We now discover that the Gram-positive Bacillus subtilis has an evolutionarily distinct ribosome rescue factor named BrfA. Genetic analysis shows that B. subtilis requires the function of either trans-translation or BrfA for growth, even in the absence of proteotoxic stresses. Biochemical and cryo-electron microscopy (cryo-EM) characterization demonstrates that BrfA binds to non-stop stalled ribosomes, recruits homologous RF2, but not RF1, and induces its transition into an open active conformation. Although BrfA is distinct from E. coli ArfA, they use convergent strategies in terms of mode of action and expression regulation, indicating that many bacteria may have evolved as yet unidentified ribosome rescue systems.