Phylogeny of conserved adenines in linkers of Group-I introns

Abstract

We have analyzed the linkers in group-I introns, a characteristic region that is crucial to the folding and splicing process of the folded RNA, in seventy sequences spreading across r-RNA, t-RNA and organelle genes from various organisms including algae, fungi and protozoa. The study revealed a high degree of consensus of specific adenine residues in J3/4, J6/7 and J8/7 stems of the linker regions that were required to stabilize the local orientation, either as single residue or by forming unusual base pairs along with divalent metal ions. Conservation of these residues in the Group-I intron linkers suggests their significant contribution to the folded structure whose bonding and geometry recruit metal ions to interact in stabilizing the folded nature of RNA.