Poster abstracts
Poster number 153 submitted by Brandon Iwaniec
Surveying tRNA introns across the eukaryotic tree: The intron in tRNATyr-GUA is almost universal, but some species lack all tRNA introns
Brandon Iwaniec (Department of Molecular Genetics and Center for RNA Biology, The Ohio State University ), Ambro van Hoof (Department of Molecular Genetics and Center for RNA Biology, The Ohio State University )
Abstract:
The existence of tRNAs containing introns is thought to be universal throughout eukaryotes. Our recent work shows that within metazoan specifically, introns in Tyr-GUA, Ile-UAU, and Leu-CAA tRNAs are very prevalent, while other tRNAs largely lack introns. We also showed that some nematode species have lost introns in Tyr-GUA and Ile-UAU tRNAs, and one nematode species, Levipalatum texanum, has lost all tRNA introns. The lack of introns in L. texanum is accompanied by the absence of the tRNA endonuclease, one of the two enzymes required for tRNA splicing. Here we expand on this work by more broadly studying the distribution of tRNA introns. We analyzed available genomes spanning 105 Nematoda genera. While L. texanum remains unique among the Nematoda in the complete absence of tRNA introns, we found that species of the infraorder Tylenchomorpha are missing the intron in Ile-UAU tRNA. We also examined tRNA intron conservation in early branching eukaryotes. While introns in Tyr-GUA, Ile-UAU, and Leu-CAA are prevalent in animals, only Tyr-GUA contained introns in most early branching eukaryotes. Two early branching eukaryotes, one in the Fornicata and one in the Stramenopila, contained no predicted tRNA introns nor homologs of tRNA endonuclease, while other Fornicate and Stramenopila did. These analyses indicate that the intron of Tyr-GUA tRNA is conserved from the last common ancestor of all eukaryotes and therefore must have an important function, but that in at least three branches of the eukaryotic tree all tRNA introns and the tRNA endonuclease were lost.
Keywords: tRNA introns, Nematodes