Book of Abstracts: Albany 2005
Tracing Ancient Mini-genes in Modern mRNA Sequences
From the early evolution theory that is based on reconstruction of the triplet code development (1, 2) it follows that the earliest mRNAs were short (∼20 nt) CG-rich polynucleotides (3). These short sequences could form hairpins, which would be of high evolutionary advantage because of stability and uniqueness of functional conformations. Based on the triplet code evolution chart (2), one can deduce that purines and pyrimidines in the second triplet positions are highly conserved through evolution, compared to the first and second triplet positions. Thus, the speculated earliest hairpins would largely lose the initial complementarity at the first and third positions of the triplets -- but their second positions should, perhaps, rather retain some complementary. Thus, by examining only the second positions in the triplets of modern mRNA sequences one may find remnants of those ancient hairpins. Indeed, computational analysis of modern prokaryotic mRNA sequences reveals excess population of such hairpins with stem size of three triplets and loops consisting of one triplet. These results are in full accord with the previous estimates for the earliest mini-genes size (3).
I.G. is supported by the Lynn and William Frankel Center for Computer Sciences.
References and Footnotes