In the genome, the genes coding for similar proteins that are regulated jointly are usually found nearby. But there are also genes that do not have this feature and yet are held together in the genome. Why separate, or not, some genes, ancestrally linked in the genome, is a question that now has a new scientific answer, as appears from an article published in the journal of Genome Research.
A study of the University of Barcelona demonstrates for the first time, how genes can be separated along the evolutionary lineages through the mechanism of retrotransposition, which is DNA synthesis from RNA through reverse transcriptase.
Sign the new study, the researchers Jordi Garcia-Fernandez, Ignacio Maeso and Manuel Irimia, Department of Genetics and Institute of Biomedicine, University of Barcelona (IBUB), scientists from the teams led by Jose Luis Gomez-Skarmeta (Andalusian Center for Developmental Biology, CSIC), and Sonsoles Campuzano, Center for Molecular Biology Severo Ochoa, CSIC, and experts from the National University of Singapore.
The human genome contains many retro secuencias, i.e. segments that are the result of reverse transcription of RNA and integration of new DNA at new points of the genome. Reverse transcriptase, an enzyme that participates in the synthesis and maintenance of telomeres (chromosome ends), is responsible for this particular molecular mechanism.
As a preview, the new paper describes how the retrotransposition has also helped decouple genes that were coming in a million years in evolution. “Until now, only two known mechanisms to separate genes: complete genome duplication and loss of one copy and tandem duplication and loss of one copy, some molecular processes that have taken place at different times of the biological evolution. In the new paper, we describe for the first time a new way of separation between genes”, explains Jordi Garcia-Fernandez.
The work of Genome Research, focused on the field of genomic architecture is based on the study of gene Sosondowah that topographic scale is adjacent to the Iroquois genes, a gene cluster involved in neurogenesis in the Drosophila nervous system and vertebrates. “Iroquois genes – Garcia-Fernandez – points are flanked by extensive areas that are deserts gene, i.e., very poor areas of the genome in genes and tend to double. In the genome of vertebrates, in particular, there are over 3,000 ultra conserved regulatory regions, and some of these areas are located within the Iroquois complex”.
According to the authors, for most metazoans studied, the gene Sosondowah (Sowah) would be tied to the Iroquois, because Sowah contains in its introns (non-coding regions), a series of key regulatory regions for genes Iroquois.
In vertebrates, however, would have escaped Sosondowah through retrotransposition mechanisms in an evolutionary scenario described now as a scoop, and characterized by the conservation of gene Sosondowah introns and loss of the exons (coding regions) along biological evolution.