Proximity labeling facilitates defining neighborhood proteome of photosystem II oxygen evolution complex in a model cyanobacterium

APEX2-based proximity labeling coupled with mass spectrometry have great potential for spatiotemporal identification of proteins proximal to a protein complex of interest. Using this approach it is feasible to define the proteome neighborhood of important protein complexes in a popular photosynthetic model cyanobacterium Synechocystis sp. PCC6803 (hereafter named as Synechocystis). To this end, we developed a robust workflow for APEX2-based proximity labeling in Synechocystis, and used the workflow to identify proteins proximal to the photosystem II (PS II) oxygen evolution complex (OEC) through fusion APEX2 with a luminal OEC subunit, PsbO.