![]() Recent studies have provided evidence of viral acquisition of host genes encoding enzymes in key metabolic pathways, such as phosphate metabolism, nitrogen metabolism, photosynthesis and pigment biosynthesis, pentose phosphate pathway, nucleic acid synthesis and others. The identification of auxiliary metabolic genes found in viral genomes is enabling a deeper understanding of the functions that increase viral fitness and the mechanism in which these functions are promoted. For example, the contribution of the viral psbA gene, which is a key factor in host photosynthesis, was shown to increase the viral genome number produced during the lytic cycle of cyanophage P-SSP7. It was suggested that such genes improve viral fitness by supporting key steps in host metabolism and were therefore termed ‘auxiliary metabolic genes’. One of the key aspects of viral evolution is the acquisition of host genes and their fixation in the viral genomes. The high abundance of viruses combined with evidence that viral particles are a major source of planktonic mortality and horizontal gene transfer demonstrate the immense influence of the virosphere on the ecology and biology of the marine environment. Viruses are the most abundant biological entities in the marine environment, with observations of millions of viral particles per single drop of water. Our naïve metagenomic analyses strongly support the well-established notion that viral auxiliary genes promote viral replication via both degradation of host DNA and RNA as well as a shift of the host metabolism towards nucleotide biosynthesis, clearly indicating that comparative metagenomics can be used to understand different environments and systems without prior knowledge of pathways involved. ![]() In addition, these enriched genes were found to be of modular nature, participating in several pathways. Furthermore, we observed that sequential reactions are promoted in pathways having a high proportion of enriched genes. Moreover, many other viral-enriched metabolic pathways were found to be closely associated with the purine and pyrimidine metabolism pathways. Our analysis of the viral-enriched pathways revealed that purine and pyrimidine metabolism pathways are among the most enriched pathways. Viral-enriched genes were mapped to a “global metabolism network” that comprises all KEGG metabolic pathways. To initially identify enriched auxiliary genes, we analyzed metagenomic microbial reads from the Global Ocean Survey (GOS) dataset that were characterized as viral, as well as marine virome and microbiome datasets from the Line Islands. In this study, we searched for enriched viral auxiliary genes and mapped them to metabolic pathways. While many individual auxiliary genes were observed in viral genomes and metagenomes, there is great importance in investigating the abundance of auxiliary genes and metabolic functions in the marine environment towards a better understanding of their role in promoting viral reproduction. It is assumed that these genes are fixed in viral genomes as a result of a selective force, favoring viruses that acquire specific metabolic functions. Viral genomes often contain metabolic genes that were acquired from host genomes (auxiliary genes).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |