翻译沉默的100S核糖体是二聚体70S复合物的一种鲜为人知的形式,在所有细菌门中普遍存在。冬眠的100S核糖体的消除导致翻译抑制,核糖体不稳定,抗生素敏感性,和一些细菌的生物膜缺陷。在Firmicutes中,如机会病原体金黄色葡萄球菌,一种称为冬眠促进因子(HPF)的190个氨基酸的蛋白质通过HPF同源二聚体之间的直接相互作用二聚化并连接两个70S核糖体,每个HPF单体拴在一个单独的70S复合物上。虽然在gammaproteobacteria和蓝细菌中100S核糖体的形成是在指数后生长期和黑暗期间专门诱导的,分别,Firmicutes中的100S核糖体是由滞后对数期到稳定期组成的。关于控制hpf表达和100S核糖体丰度的调节途径知之甚少。这里,我们表明,一般应激反应(GSR)σ因子(SigB)和GTP敏感转录因子(CodY)整合营养和热信号来调节金黄色葡萄球菌的hpf合成,导致败血症感染小鼠模型中病原体的毒力增强。Hpf的CodY依赖性调节是菌株特异性的。上位分析进一步证明了CodY以条件依赖性方式在GSR途径的上游起作用。结果揭示了金黄色葡萄球菌应激生理之间的重要联系,核糖体代谢,和感染生物学。重要性70S核糖体(100S复合物)的二聚化在主要人类病原体金黄色葡萄球菌的翻译调节和感染性中起着重要作用。调节100S核糖体丰度的途径仍然难以捉摸。我们确定了一种代谢和营养敏感的转录因子,CodY,以营养和温度依赖性方式充当hpf表达的激活剂和阻遏剂。此外,CodY介导的hpf活化掩盖了源自一般应激反应SigB启动子的次级hpf转录物。CodY和SigB调节毒力基因库。核糖体稳态与两种主要毒力调节剂之间的意外联系为替代可药用位点提供了新的机会。
The translationally silent 100S ribosome is a poorly understood form of the dimeric 70S complex that is ubiquitously found in all bacterial phyla. The elimination of the hibernating 100S ribosome leads to translational derepression, ribosome instability, antibiotic sensitivity, and biofilm defects in some bacteria. In Firmicutes, such as the opportunistic pathogen Staphylococcus aureus, a 190-amino acid protein called hibernating-promoting factor (HPF) dimerizes and conjoins two 70S ribosomes through a direct interaction between the
HPF homodimer, with each
HPF monomer tethered on an individual 70S complex. While the formation of the 100S ribosome in gammaproteobacteria and cyanobacteria is exclusively induced during postexponential growth phase and darkness, respectively, the 100S ribosomes in Firmicutes are constitutively produced from the lag-logarithmic phase through the post-stationary phase. Very little is known about the regulatory pathways that control
hpf expression and 100S ribosome abundance. Here, we show that a general stress response (GSR) sigma factor (SigB) and a GTP-sensing transcription factor (CodY) integrate nutrient and thermal signals to regulate hpf synthesis in S. aureus, resulting in an enhanced virulence of the pathogen in a mouse model of septicemic infection. CodY-dependent regulation of
hpf is strain specific. An epistasis analysis further demonstrated that CodY functions upstream of the GSR pathway in a condition-dependent manner. The results reveal an important link between S. aureus stress physiology, ribosome metabolism, and infection biology.IMPORTANCE The dimerization of 70S ribosomes (100S complex) plays an important role in translational regulation and infectivity of the major human pathogen Staphylococcus aureus Although the dimerizing factor HPF has been characterized biochemically, the pathways that regulate 100S ribosome abundance remain elusive. We identified a metabolite- and nutrient-sensing transcription factor, CodY, that serves both as an activator and a repressor of hpf expression in nutrient- and temperature-dependent manners. Furthermore, CodY-mediated activation of
hpf masks a secondary
hpf transcript derived from a general stress response SigB promoter. CodY and SigB regulate a repertoire of virulence genes. The unexpected link between ribosome homeostasis and the two master virulence regulators provides new opportunities for alternative druggable sites.