The amplification of oligonucleotide themes in the evolution of themyc protooncogene family |
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Authors: | Jiří Doskočil |
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Institution: | (1) Institute of Molecular Genetics, Czech Academy of Sciences, Flemingovo n. 2, 6, 16610 Praha, Czech Republic;(2) Present address: Institute of Molecular Genetics, Flemingovo n. 2, 166 37 Prague 6, Czech Republic |
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Abstract: | The evolutionary past of intragenic repeats in protein-coding exons of c-, N-, L-, and s-myc-protooncogene subfamilies was elucidated. Apparently these genes evolved by succession of distinct unit events rather than
by a steady flow of random point mutations. An evolutionary event probably involved a duplication of the whole gene, which
was followed by amplification of progressively shorter oligonucleotide themes and motifs. The repeats were either joined in
tandem or one of the copies was transposed and integrated elsewhere within the same exon. In some instances multiple fragments
of an amplified theme were integrated at several sites. Direct repeats were found to prevail over inverted ones. By reconstructing
the fate of repeats in the course of evolution of vertebrates, the origins of some functional domains could be traced to the
initial amplification event. For example, an N-myc-specific domain was created by tandem duplication of a single-copy theme of L-myc exon; at the time of divergence of the c-myc and N-myc, the tandem duplex underwent a new round of duplication followed by transposition of the new copy, thus accounting for the
formation of a new domain specific for c-myc. The model proposed here may be regarded as a molecular-level equivalent of the theory of punctuated equilibria.
This is the author's last paper; it was submitted shortly before his death. The proofs were corrected by Michal Dvorak
Correspondence to: M. Dvorak |
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Keywords: | myc-Protooncogenes Intragenic repeats Oligonucleotide amplification Domain evolution Hierarchy of amplifications Primeval genes Periodic structures Punctuated equilibria Evolutionary potential |
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