From End to End: tRNA Editing at 5'- and 3'-Terminal Positions

• Main Authors: Heike Betat, Yicheng Long, Jane E. Jackman, Mario Mörl
• Format: Article
• Language: English
• Published: MDPI AG 2014-12-01
• Series: International Journal of Molecular Sciences
• Subjects: tRNA; editing; tRNA processing; tRNA maturation
• Online Access: http://www.mdpi.com/1422-0067/15/12/23975

During maturation, tRNA molecules undergo a series of individual processing steps, ranging from exo- and endonucleolytic trimming reactions at their 5'- and 3'-ends, specific base modifications and intron removal to the addition of the conserved 3'-terminal CCA sequence. Especially in mitochondria, this plethora of processing steps is completed by various editing events, where base identities at internal positions are changed and/or nucleotides at 5'- and 3'-ends are replaced or incorporated. In this review, we will focus predominantly on the latter reactions, where a growing number of cases indicate that these editing events represent a rather frequent and widespread phenomenon. While the mechanistic basis for 5'- and 3'-end editing differs dramatically, both reactions represent an absolute requirement for generating a functional tRNA. Current in vivo and in vitro model systems support a scenario in which these highly specific maturation reactions might have evolved out of ancient promiscuous RNA polymerization or quality control systems.