Transfêrencia horizontal de gene: avaliando padrões

Abstract

The term horizontal gene transfer (HGT), or lateral gene transfer (LGT) is used to refer to the movement of genetic information between distantly related organisms beyond the natural barrier and mating transmission from parent to offspring known as vertical gene transfer (VGT). Thus, the exchange of genes between organisms have been associated with the acquisition of new features that give the recipient a selective advantage on the population where it currently is. However, the effects of gene transfer events also may be neutral or detrimental for the receptor genome. The HGT can be identified by the presence of a similar gene in distantly related organisms. The horizontal transfer is a common event in bacteria and its importance in the evolution of these organisms is very clear. On the other hand, in eukaryotes this phenomenon is not yet entirely understood because of lack of research and data. However, in recent years there has been an increasing number of sequenced eukaryotic genomes and investigation of HGT events, both in unicellular and multicellular organisms. So it became necessary to sum up this data and organize it in order to visualize these events in a broadly perspective. The main goal of this study was to review the literature about HGT and to create a database of horizontally transferred genes having eukaryotes as recipient organism. In addition we also analyzed parameters to clarify processes that may govern such events in nature. Several rounds of literature search were performed in PubMed and Google Schollar. The information about the genes were extracted as their gene IDs and their potential donors. The IDs of genes have been submitted to Kobas 2.0 platform in order to make its fucntional annotation. 447 genes were transferred to four species (Homo sapiens, Caenorhabditis elegans, Drosophila melanogaster and Physcomitrella patens). Among these, there was a higher occurrence of transferred genes from prokaryotic organisms (199 genes) and from unicellular eukaryotes (protists, with 140 genes found) to multicellular eukaryotes. The remaining genes are divided between plants, fungi and Archeas. The largest association of eukaryotic organisms with prokaryotes and higher taxon sampling of bacterial genomic sequences are proposed to explain these results. The gene function prediction analysis showed a trend in the transfer of genes that act in sugar metabolism, amino acid, nucleotide and secondary metabolism, transmitting a wide variety of metabolic functions, suggesting that HGT has played an important role in expanding and reconfiguring metabolic core and nutrient processing capacity and enables the adaptation of these organisms to unfavorable conditions. This work brings together, for the first time, the information about horizontally transferred genes fulfilling a first step towards the creation of a public database