tRNA-Cys gene clusters exhibit high variability in Arabidopsis thaliana
Szymanski M., Maurya A., Kopec P., Karlowski WM.
AbstractAlthough most of the genes encoding tRNAs in plants are dispersed throughout the genome, a fraction of them form tRNA gene clusters. In Arabidopsis thaliana, the smallest of tRNA clusters on chromosome 5 consists of four tRNA-Cys-GCA genes placed within repeating units of 0.4 kbp. A systematic analysis of the genomic sequences of syntenic regions from various ecotypes of A. thaliana showed that the general structure of the cluster, consisting of a tRNA-Cys pseudogene followed by repeating units containing tRNA-Cys genes, is well conserved. However, there is significant heterogeneity in the number of repeating units between different ecotypes. A unique feature of this cluster is the presence of putative transposable elements (Helitron). In addition, two further tRNA-Cys gene mini-clusters (gene pairs) in A. thaliana were identified. RNA-seq-based evaluation of expression of tRNA-Cys-GCA genes showed a positive signal for 11 out of 13 unique transcripts. An analysis of the conservation of the tRNA-Cys clusters from A. thaliana with the corresponding regions from four other Arabidopsis species suggests a sequence of events that led to the divergence of these regions.