de Crécy-Lagard Valérie, Marck Christian, Grosjean Henri
Department of Microbiology and Cell Science, University of Florida, P.O. Box 110700, Gainesville, FL 32611-0700, USA.
Trends Cell Mol Biol. 2012;7:11-34.
A comparative genomic analysis of the recently sequenced human body louse unicellular endosymbiont Candidatus Riesia pediculicola with a reduced genome (582 Kb), revealed that it is the only known organism that might have lost all post-transcriptional base and ribose modifications of the tRNA body, retaining only modifications of the anticodon-stem-loop essential for mRNA decoding. Such a minimal tRNA modification set was not observed in other insect symbionts or in parasitic unicellular bacteria, such as Mycoplasma genitalium (580 Kb), that have also evolved by considerably reducing their genomes. This could be an example of a minimal tRNA modification set required for life, a question that has been at the center of the field for many years, especially for understanding the emergence and evolution of the genetic code.
对最近测序的人体虱子单细胞内共生菌“嗜虱念珠藻（Candidatus Riesia pediculicola）”进行的比较基因组分析显示，其基因组已缩减至582千碱基对，它是已知唯一可能已丧失转运核糖核酸（tRNA）主体所有转录后碱基和核糖修饰的生物体，仅保留了对信使核糖核酸（mRNA）解码至关重要的反密码子茎环修饰。在其他昆虫共生菌或寄生单细胞细菌（如基因组也经大幅缩减的生殖道支原体，其基因组大小为580千碱基对）中未观察到如此简约的tRNA修饰集。这可能是生命所需的最小tRNA修饰集的一个实例，多年来这一问题一直是该领域的核心，尤其是对于理解遗传密码的出现和进化而言。
