Book of Abstracts: Albany 2007
June 19-23 2007
Duplex Nature of Ancient Genes
Starting from reconstruction of evolution of the triplet code (1), and appreciating conservation of middle purines or pyrimidines in the codons of modern mRNA, we were able to detect traces of the early minigenes in numerous prokaryotic mRNA sequences. The hypothesis that many of those minigenes possessed the form of hairpins was confirmed. Predominant size of detected ancient hairpins was found to correspond to 6-7 amino acids, in accordance with earlier independent estimates.
The spectrum of the genes-hairpins displays an interesting feature: the frequencies of occurrences of complementary hairpin sequences are correlated. In other words, if some hairpin sequence occurs frequently, so does its complementary sequence (2). Analysis of all 128 heptapeptides in binary presentation (amino acids with purine or pyrimidine-central codons) showed the same complementary parity in corresponding scores for complete proteomes of 13 phylogenetically diverse prokaryotes. This demonstrates that the hypothesized duplex coding at the beginning of Life can be still detected in modern sequences.
The transition from the double-stranded coding stage to a single-stranded coding is further unveiled by detailed analysis of the complementary parity phenomenon.
I. G. is supported by the Lynn and William Frankel Center for Computer Sciences and the Pratt Fellowship.
References and Footnotes
1Department of Computer Science