Multiply Expressed tRNA Genes?

Abstract

Some coding (mRNA) genes are known to express into several different amino-acid chains by intron and exon shuffling. There are computational arguments that an analogous mechanism may give rise to two different products from a single non-coding gene. We propose, based on bioinformatics' evidence, that the number of different products from some of these non-coding genes may indeed be greater than two. The present study demonstrates that, in some cases, intron repositioning and partial exon-intron shuffling lead to newer putative tRNAs. An intricate and entangled organizational network performs a complex optimization of the secondary structures at the exon-intron boundaries. We find up to four different RNAs are encoded cryptically in a single composite tRNA gene. But it is the remarkably high fidelity of the secondary structures and the conserved sequences of all the tRNAs that are embedded that leads to this hypothesis.