biostudies-literatureNadel OEuropean Research Council434-442https://www.ebi.ac.uk/biostudies/studies/S-EPMC12695635biostudies-literatureUnknown648(8093)Marine picocyanobacteria are abundant photosynthetic organisms of global importance. They coexist in the ocean with cyanophages-viruses that infect cyanobacteria. Cyanophages carry many auxiliary metabolic genes acquired from their hosts that are thought to redirect host metabolism for the phage's benefit^1-5. One such gene is nblA, which is present in multiple cyanophage families^2,6-8. Under nutrient deprivation cyanobacterial NblA is responsible for inducing proteolytic degradation of the phycobilisome^9-11, the large cyanobacterial photosynthetic light-harvesting complex. This increases the pool of amino acids available for essential tasks¹¹, serving as a survival mechanism¹². Ectopic expression of different cyanophage nblA genes resuNatureViral NblA proteins negatively affect oceanic cyanobacterial photosynthesis.PMC12695635321647646868Hanna RTahan RShitrit DKleifeld ORozenberg ALindell DBeja ONadel OPekarsky IfalseViral NblA proteins negatively affect oceanic cyanobacterial photosynthesis.Marine picocyanobacteria are abundant photosynthetic organisms of global importance. They coexist in the ocean with cyanophages-viruses that infect cyanobacteria. Cyanophages carry many auxiliary metabolic genes acquired from their hosts that are thought to redirect host metabolism for the phage's benefit^1-5. One such gene is nblA, which is present in multiple cyanophage families^2,6-8. Under nutrient deprivation cyanobacterial NblA is responsible for inducing proteolytic degradation of the phycobilisome^9-11, the large cyanobacterial photosynthetic light-harvesting complex. This increases the pool of amino acids available for essential tasks¹¹, serving as a survival mechanism¹². Ectopic expression of different cyanophage nblA genes resu2025-01-01T00:00:00Z2025 Dec2026-07-15T11:16:07.656Z2026-07-04T03:11:43.649ZS-EPMC126956354122499610.1038/s41586-025-09656-x