RsgA(小核糖体亚基,30S,GTPase),晚期生物发生因子,从30S-RbfA复合物中释放RbfA。大肠杆菌ΔrsgA(rsgA缺失)显示出缓慢的生长表型,并且17SrRNA(16SrRNA的前体)和核糖体亚基的积累增加。这里,我们表明,通过同时过表达起始tRNA(i-tRNA)来增强多拷贝infB(IF2)对ΔrsgA菌株的拯救,提示启动复合物形成在生长拯救中的作用。IF2/i-tRNA的协同效应伴随着17SrRNA(至16S)的加工增加,和16SrRNA3'-次要结构域的保护。重要的是,我们证明了一种结合IF2的抗惊厥药物,拉莫三嗪,也挽救了ΔrsgA菌株的生长。拯救伴随着17SrRNA的加工增加,16SrRNA的3'-次要结构域的保护,多体谱中70S核糖体增加。然而,Ltg对ΔrsgA菌株具有抑制作用,该菌株的生长已经被rbfA中的L83R突变挽救。有趣的是,就像野生型infB,LtgRinfB等位基因的过量生产(在其结构域II中具有indel突变)也挽救了ΔrsgA菌株(独立于Ltg)。我们的观察结果表明,IF2在挽救ΔrsgA菌株中具有双重作用。首先,连同i-tRNA,IF2促进17SrRNA的最终加工步骤。第二,IF2的构象在功能上补偿了RsgA,虽然很糟糕,在30S生物发生期间。
目的:RsgA是一种晚期核糖体生物发生因子。早些时候,infB(IF2)被分离为大肠杆菌ΔrsgA菌株的多拷贝抑制物。IF2如何拯救菌株生长仍不清楚。这项研究表明,(i)在同时过表达起始tRNA和(ii)IF2的构象时,可以增强菌株中大肠杆菌ΔrsgA的多拷贝infB介导的生长挽救和17S前体到16SrRNA的加工,当IF2过量产生或当大肠杆菌ΔrsgA用Ltg(一种与IF2的结构域II结合的抗惊厥药物)处理时,其发生率增加,补偿RsgA的功能。因此,这项研究揭示了IF2在核糖体生物发生中的另一个作用。
RsgA (small ribosomal subunit, 30S, GTPase), a late-stage biogenesis factor, releases RbfA from 30S-RbfA complex. Escherichia coli ΔrsgA (deleted for rsgA) shows a slow growth phenotype and an increased accumulation of 17S rRNA (precursor of 16S rRNA) and the ribosomal subunits. Here, we show that the rescue of the ΔrsgA strain by multicopy infB (IF2) is enhanced by simultaneous overexpression of initiator tRNA (i-tRNA), suggesting a role of initiation complex formation in growth rescue. The synergistic effect of IF2/i-tRNA is accompanied by increased processing of 17S rRNA (to 16S), and protection of the 16S rRNA 3\'-minor domain. Importantly, we show that an IF2-binding anticonvulsant drug, lamotrigine (Ltg), also rescues the ΔrsgA strain growth. The rescue is accompanied by increased processing of 17S rRNA, protection of the 3\'-minor domain of 16S rRNA, and increased 70S ribosomes in polysome profiles. However, Ltg becomes inhibitory to the ΔrsgA strain whose growth was already rescued by an L83R mutation in rbfA. Interestingly, like wild-type infB, overproduction of LtgRinfB alleles (having indel mutations in their domain II) also rescues the ΔrsgA strain (independent of Ltg). Our observations suggest the dual role of IF2 in rescuing the ΔrsgA strain. First, together with i-tRNA, IF2 facilitates the final steps of processing of 17S rRNA. Second, a conformer of IF2 functionally compensates for RsgA, albeit poorly, during 30S biogenesis.
RsgA is a late-stage ribosome biogenesis factor. Earlier, infB (IF2) was isolated as a multicopy suppressor of the Escherichia coli ΔrsgA strain. How IF2 rescued the strain growth remained unclear. This study reveals that (i) the multicopy infB-mediated growth rescue of E. coli ΔrsgA and the processing of 17S precursor to 16S rRNA in the strain are enhanced upon simultaneous overexpression of initiator tRNA and (ii) a conformer of IF2, whose occurrence increases when IF2 is overproduced or when E. coli ΔrsgA is treated with Ltg (an anticonvulsant drug that binds to domain II of IF2), compensates for the function of RsgA. Thus, this study reveals yet another role of IF2 in ribosome biogenesis.