The natural intron sequence of human tyrosine pre-transfer RNA is not a temporal stabilizer for cloverleaf structure.

We have developed the hyperprocessing technique to evaluate the stability of the cloverleaf shape of pre-transfer RNA (pre-tRNA). Application of this strategy to hyperprocessible human tyrosine pre-tRNA indicated that the natural intron sequence did not contribute to stabilization of the cloverleaf shape of this pre-tRNA, while the artificial intron with elongated anticodon-stem completely inhibited hyperprocessing of it. Our data suggested that the contemporary intron sequence may be a vestige of the ancient pre-biotic world, but not has been retained as a temporal stabilizer of the pre-tRNA before the base modifications.