Analysis of the phage sequence space: the benefit of structured information.

Phages are the most abundant biological entities on Earth and are central players in the evolution of their bacterial hosts and the emergence of new pathogens. In addition, they bear an enormous potential for the development of new drugs, therapies or nanotechnologies. As a result, interest in phages is reviving. In the genomic era, our perspective on the phage sequence space remains incredibly sparse. The modular and combinatorial structure of phage genomes is largely documented. It is confirmed by new sequence information and it fuels a recurrent debate on the need to revise phage taxonomy. The absence of structured, computer readable information on phages is a major bottleneck for an extensive global analysis of phage genomes and their relationships, but such information is essential to reassess phage classification. Based on the ACLAME database, which is dedicated to the organization and analysis of prokaryotic mobile genetic elements, we discuss here how structured information on phage-encoded proteins helps global in silico analysis and allows the prediction of prophages in bacterial genome sequences, providing access to additional phage sequence information.