Eukaryotic Noncoding DNA Sequences Provide Genes with an Additional Protection against Chemical Mutagens

L. I. Patrushev^a,# and I. G. Minkevich^b

^# Fax/phone: +7 (495) 429-8610; e-mail: patrush@mail.ibch.ru
^a Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117997 Russia
^b Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 6, Pushchino, Moscow oblast, 142290 Russia

Received September 16, 2005; in final form, October 14, 2005

Abstract: A quantitative model was developed that identified a new function of noncoding sequences in the eukaryotic genome, namely, the protection of coding sequences against chemical (mainly endogenous) mutagens. It was shown that, under common ecological conditions, the number of nucleotides damaged by modification in coding sequences of the genome is inversely proportional to the size of their noncoding parts. Noncoding sequences can differently protect single genetic loci from chemical mutagens by the formation of specific spatial structures of the protected loci in the interphase nuclei. The significant differences in genome sizes between species (C-value paradox) can be explained by different contributions of noncoding sequences to the total effect of genome protection from endogenous chemical mutagens.

Key words: coding sequences, evolution, genome, noncoding sequences, mutations, C-value paradox

Russian Journal of Bioorganic Chemistry 2006, 32 (4):368-372