AS-1 cyanophage infection inhibits the photosynthetic electron flow of photosystem II in Synechococcus sp. PCC 6301, a cyanobacterium.

In Synechococcus sp. cells AS-1 cyanophage infection gradually inhibits the photosystem II mediated photosynthetic electron flow whereas the activity of photosystem I is apparently unaffected by the cyanophage infection. Transient fluorescence induction and flash-induced delayed luminescence decay studies revealed that the inhibition may occur at the level of the secondary acceptor, QB of photosystem II. In addition, the breakdown of D1-protein is inhibited, comparable to DCMU-induced protection of D1-protein turnover, in AS-1-infected cells.