The mitochondrial genome of the nematode Romanomermis culicivorax encodes for
miniaturized hairpin-like tRNA molecules that lack D- as well as T-arms, strongly deviating from
the consensus cloverleaf. The single tRNA nucleotidyltransferase of this organism is fully active on
armless tRNAs, while the human counterpart is not able to add a complete CCA-end. Transplanting
single regions of the Romanomermis enzyme into the human counterpart, we identified a beta-turn
element of the catalytic core that—when inserted into the human enzyme—confers full CCA-adding
activity on armless tRNAs. This region, originally identified to position the 30
-end of the tRNA
primer in the catalytic core, dramatically increases the enzyme’s substrate affinity. While conventional
tRNA substrates bind to the enzyme by interactions with the T-arm, this is not possible in the case of
armless tRNAs, and the strong contribution of the beta-turn compensates for an otherwise too weak
interaction required for the addition of a complete CCA-terminus. This compensation demonstrates
the remarkable evolutionary plasticity of the catalytic core elements of this enzyme to adapt to
unconventional tRNA substrates.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:88931 |
| Date | 10 January 2024 |
| Creators | Hennig, Oliver, Philipp, Susanne, Bonin, Sonja, Rollet, Kévin, Kolberg, Tim, Jühling, Tina, Betat, Heike, Sauter, Claude, Mörl, Mario |
| Publisher | MDPI |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 9047, 10.3390/ijms21239047 |
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