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. Author manuscript; available in PMC: 2019 Dec 1.
Published in final edited form as: IUBMB Life. 2018 Oct 25;70(12):1207–1213. doi: 10.1002/iub.1957

FIG 1. Intracellular compartmentalization of tRNAs and modification enzymes and their role in affecting mitochondria decoding and evolution.

FIG 1.

Methylation at position 37 of certain tRNAs is important for translational fidelity and is also the precursor for another frameshift-preventing modification, wyosine and derivatives. Two versions of the latter exist in T. brucei one cytoplasmic and the other mitochondrial, but because a robust and promiscuous tRNA import pathway tRNAs modified to various extents have to be further modified to be fully functional. The unique wyosine formation pathway of T. brucei is proposed as part of the evolutionary adaption that permitted the organelle to cope with an abundance of U-rich sequences created by RNA editing, while preventing ribosomal frameshifting. NPC refers to the Nuclear Pore Complex, m1G37 refers to 1-methylguanosine found at position 37 of the anticodon of tRNAs Ile, His, Pro, Leu, Arg and Phe. In tRNAPhe this methylation is further modified to wybutosine (yW) or wyosine (imG) dependent on location.