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Abstract：
The ribosomal protein uS12 is conserved across all domains of life. Recently, a heterozygous spontaneous mutation in human uS12 (corresponding to R49K mutation immediately downstream of the universally conserved 44 PNSA47 loop in Escherichia coli uS12) was identified for causing ribosomopathy, highlighting the importance of the PNSA loop. To investigate the effects of a similar mutation in the absence of any wild-type alleles, we mutated the rpsL gene (encoding uS12) in E. coli. Consistent with its pathology (in humans), we were unable to generate the R49K mutation in E. coli in the absence of a support plasmid. However, we were able to generate the L48K mutation in its immediate vicinity. The L48K mutation resulted in a cold sensitive phenotype and ribosome biogenesis defect in the strain. We show that the L48K mutation impacts the steps of initiation and elongation. Furthermore, the genetic interactions of the L48K mutation with RRF and Pth suggest a novel role of the PNSA loop in ribosome recycling. Our studies reveal new functions of the PNSA loop in uS12, which has so far been studied in the context of translation elongation.
摘要：
核糖体蛋白uS12在生命的所有域中都是保守的。最近,人类uS12中的杂合自发突变（对应于大肠杆菌uS12中普遍保守的44PNSA47环下游的R49K突变）被鉴定为引起核糖体病，强调PNSA循环的重要性。为了研究在没有任何野生型等位基因的情况下相似突变的影响，我们在大肠杆菌中突变了rpsL基因(编码uS12)。与其病理（在人类中）一致，在缺乏支持质粒的情况下，我们无法在大肠杆菌中产生R49K突变。然而,我们能够在其附近产生L48K突变。L48K突变导致该菌株的冷敏感表型和核糖体生物发生缺陷。我们表明L48K突变影响起始和延伸的步骤。此外，L48K突变与RRF和Pth的遗传相互作用提示PNSA环在核糖体再循环中的新作用.我们的研究揭示了uS12中PNSA环的新功能，迄今为止，该功能已在翻译延伸的背景下进行了研究。
