Novel Hybrid Encodes both Continuous and Split tRNA Genes?

Abstract

tRNAs are mostly transcribed from un-fragmented genes, but occasionally also from split genes, with separated 5′ and 3′ halves. A reanalysis of the existing data on Staphylothermus marinus and Staphylothermus hellenicus hints of a novel hybrid gene that encodes both an un-fragmented and a 5′-split-half together in one. The corresponding 3′-complementgene is located elsewhere on the genome. As un-fragmented, the hybrid gene transcribes to tRNA^lys(TTT). But as 5′-half, it trans-splices with its 3′-complement-half to tRNA^lys(CTT), the tRNA missed so far. This hybrid of the split and the un-fragmented in one suggests a deeper synergy between the two, and hints of co-evolution. Furthermore, in a subtle contrast to the widely held idea of conservation of 3′-half, it is precisely the 3′-half that varies in these two tRNAs; the 5′-half remains conserved.

Key words:

• Genes
• Split-genes
• Noncoding RNA
• Gene-expression