Utilização de métodos de comparação de sequências para a detecção de genes taxonomicamente restritos

Abstract

Since the 1990s, international efforts to obtain complete genomes led to the determination of the genome of many organisms. This, coupled with great advances in computing, has allowed the use of innovative approaches in the study of structure, organization and evolution of genomes and the prediction and functional classification of genes. Among the methods most commonly employed in such analysis is the search for similarities between biological sequences. Comparative analysis of whole genome sequences indicate that each taxonomic group studied so far contain 10 to 20% of genes with no recognizable homologues in other species. It is believed that these taxonomically restricted genes (TRGs) have an important role in adaptation to particular ecological niches and may be involved in important evolutionary processes. However, the recognition of such genes is not simple, being necessary to distinguish them from spurious ORFs nonfunctional and / or artifacts from the processes of gene annotation. Furthermore, species- or genus-specific genes may be an opportunity for the development of methods for identification and / or typing, a relatively complicated task in the case of prokaryotes, where the gold standard at present involves the analysis of a group of several genes (Multilocus Sequence Typing - MLST). This study used data generated through comparative analysis of genome sequences to identify and characterize species- and genusspecific genes, which may help in the development of new methods for identification and / or typing, and can possibly shed light on important evolutionary processes (such as loss and / or origin of genes in particular lineages, as well as expansion of gene families in specific strains) involving the studied organisms.