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bioRxiv · 10.1101/2022.06.07.494954

Altered tRNA processing is linked to a distinct and unusual La protein in Tetrahymena thermophila

Kerkhofs, K.·Garg, J.·Fafard-Couture, Étienne·Abou Elela, S.·Scott, M. S.·Pearlman, R. E.·Bayfield, M. A.
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Abstract

Nascent pre-tRNAs are transcribed by RNA polymerase III and immediately bound by La proteins on the UUU-3OH sequence, using a tandem arrangement of the La motif and an adjacent RNA recognition motif-1 (RRM1), resulting in protection from 3-exonucleases and promotion of pre-tRNA folding. The Tetrahymena thermophila protein Mlp1 has been classified as a genuine La protein, despite the predicted absence of the RRM1. We found that Mlp1 functions as a La protein through binding of pre-tRNAs and affecting processing in Tetrahymena thermophila and when expressed in fission yeast. However, unlike in other examined eukaryotes, depletion of Mlp1 results in 3-trailer stabilization. We also observed that 3-trailers in Tetrahymena thermophila are uniquely short relative to other examined eukaryotes, and that 5-leaders have evolved to disfavour pre-tRNA leader/trailer pairing. Our data indicate that this variant Mlp1 architecture is linked to an altered, novel mechanism of tRNA processing in Tetrahymena thermophila.

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Kerkhofs, K., Garg, J., Fafard-Couture, Étienne, Abou Elela, S., Scott, M. S., Pearlman, R. E., Bayfield, M. A.. 2022-06-07. Altered tRNA processing is linked to a distinct and unusual La protein in Tetrahymena thermophila. https://doi.org/10.1101/2022.06.07.494954

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