Genes and Structural Proteins of the Phage Syn5 of the Marine Cyanobacteria Synechococcus
MASSACHUSETTS INST OF TECH CAMBRIDGE
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Bacteriophage have been proposed to be the most abundant organisms on the planet, at an estimated 1031 particles globally Hendrix et al., 1999. The majority of bacteriophage isolates 96 are double-stranded DNA tailed phages Caudovirales. These phages possess a distinctive icosehedral head, with a protein tail structure protruding from a single vertex. This organelle determines host specificity and provides the mechanism of passage of the phage genome into the host cell. Phages infecting differing microbial hosts may have access to a global pool of genes, albeit at different levels. Marine cyanobacteria of the genera Prochiorococcus and Synechococcus are numerically dominant photosynthetic cells in the large oligotrophic gyres of the open oceans, and contribute an estimated 30 to the oceanic photosynthetic budget. Cyanophages have been isolated which propagate on many strains of Synechococcus and Prochiorococcus. Cyanophages can effect community structure and succession through lytic infection of their hosts, and have implications in lateral gene transfer, mediated through lysogeny, mixed infections, pseudolysogeny, and transduction. The broad host ranges between genera observed in some phages indicates that lateral gene transfer is not confined to cells of the same strain. These phagehost interactions begin by host recognition by the tail of the infecting phage. Few studies have examined the structural proteins of cyanophage, partially due to the lack of a robust protocol for the growth and purification of phage particles.