The quest for viral 'photosynthesis' using both metagenomics and environmental genomics

Oded Beja
Technion

Genes that encode the photosystem II D1 protein (psbA) were recently found in several cultured cyanophage genomes. These viral photosynthesis genes may provide a beneficial trait to the viruses or to their photosynthetic cyanobacterial hosts, or even represent a previously unrecognized gene pool for formation of photosynthetic apparati.
Using both BAC based approaches (environmental Genomics) and Metagenomics we observe that between 44% (Sargasso Sea) to at least 59% (Atlantic Ocean) of environmental D1 sequences are of viral origin. Moreover, viral signatures were also detected in D1 mRNA, indicating that these photosynthetic viral genes are actively expressed in the marine environment. Overall, our environmental observations raise the possibility that marine viruses actively participate in and influence oceanic photosynthesis on a global scale. The possible implications to oceanic photosynthesis and to the carbon cycle will be discussed.