Análise global e gene a gene do GC% de vírus grandes e gigantes pertencentes ao filo Nucleocytoviricota

Abstract

Nucleocytoviricota (or NCLDV) is one of the most diverse taxonomic groups, including representatives with the largest genomes observed in the known virosphere. Genomic studies on sequence composition counts with many different approaches, one of which calculates the proportion of guanines and cytosines within the sequence, known as GC content. The GC% content can lead to important information about the organism’s biology and various biological aspects. In the present work, the GC% of 61 genomes belonging to Nuclecytoviricota was calculated gene by gene. Among these genomes are the representatives of Phycodnaviridae, Mimiviridae, Iridoviridae, Marseilleviridae, Asfaridae, Poxviridae and “Pithoviridae”, as well as unclassified lineages. Reference genomes were obtained from the public genomic database GenBank (NCBI), and multifasta files were created containing only coding sequences annotated for each genome. These files were submitted to the sequence content analysis and free access program InfoSeq, by EMBOSS (EMBL-EBI). We then obtained the GC% content of each CDS, for each genome individually, within each group and globally in Nucleocytoviricota. Our results revealed how NCLDV is diverse, not only considering the viral biology of its members, but also in the GC% composition of its genomes. The range of GC% values observed in Nucleocytoviricota is significant, and some families, such as Mimiviridae and Poxviridae, gain prominence. Although most of the analyzed genes presented GC% values close to the CDS mean, an important number of genes with GC% significantly over or below the mean was observed. Furthermore, different genomes presented clusters of genes in defined regions with percentage values of GC significantly above the average. Outlier gene sequences of each group were evaluated in order to determine presence of orthologs or potential evolutionary tendencies shared among these groups. This work brings, for the first time, a global and gene-by-gene analysis of the distribution and profile of the GC content percentage within genomes, illustrating part of the diversity within Nucleocytoviricota, and identifying possible new targets for future studies.