Cyanophages: Billions of Years of Coevolution with Cyanobacteria

Prevalent in marine and freshwater ecosystems, cyanophages compose a class of double-stranded DNA viruses that specifically infect cyanobacteria. During billions of years of coevolution, cyanophages and cyanobacteria have significantly contributed to the biogeochemical cycling and genetic diversity of aquatic ecosystems. As natural predators of cyanobacteria, cyanophages hold promise as eco-friendly agents against harmful cyanobacterial blooms. Recent technical advances in omics and cryo-electron microscopy have revealed the remarkable diversity of cyanophages in genome sequence and tail morphology. In this review, we summarize the genomic and metagenomic data, phylogenetic analyses, and diverse three-dimensional structures of cyanophages, in addition to their interplays with hosts. We also discuss the in vivo assembly processes of cyanophages, the exploration of uncultured cyanophages and host pairing, and the synthetic engineering and potential applications of cyanophages.