Viruses that infect bacteria, also called phages, are the most abundant life form on earth. They play a fundamental role in nature and in many cases can affect human health. Nonetheless, they were discovered only a little over a century ago, and there is still much to be learned about their life cycle.
A team of scientists, including several researchers from the Centro Nacional de Biotecnología of the CSIC (CNB-CSIC), has published an article in the journal Nucleic Acids Research that identifies some of the key parts of the multiplication machinery of these viruses.
In specific terms, the study analyses the replication process of phages that infect Staphylococcus aureus, a bacterium that causes skin and mucosal infections in humans.
"Phages are partly responsible for the pathogenicity associated with S. aureus. The phage’s DNA often codes for toxins that cause human disease. They can also act as vehicles that transmit virulence genes from one bacterium to another," explains Silvia Ayora, a CNB-CSIC scientist and one of the authors of the paper.
The study, carried out in collaboration with scientists from the University of Glasgow (Scotland), the Biomedicine Institute of Valencia and the University CEU Cardenal Herrera (Spain), demonstrates for the first time that the Sak and Sak 4 enzymes are essential for the reproduction of phages that affect S. aureus.
"We propose a new model of how these proteins act to replicate phage DNA," says Ayora. The authors’ model suggests states that Sak and Sak4 bind to the genetic material and work together with another protein to allow virus multiplication.
Understanding the life cycle of these phages can help to reveal the origin of the virulence of some bacteria that cause human diseases, and to encourage development of new strategies to confront them. Better understanding of the replication process of this type of virus could similarly facilitate the development of new tools that allow remodeling of bacterial genomes for biotechnological purposes.
- Neamah MM, Mir-Sanchis I, López-Sanz M, Acosta S, Baquedano I, Haag AF, Marina A, Ayora S, Penadés JR. Sak and Sak4 recombinases are required for bacteriophage replication in Staphylococcus aureus. Nucleic Acids Res. 2017 May 5. doi: 10.1093/nar/gkx308.
Replication cycle of bacteriophages that affect Staphylococcus aureus / Silvia Ayora, CNB-CSIC