Antimycin A induces light hypersensitivity of PSII in the presence of quinone QB-site binding herbicides.

Photosynthetic electron transport consists of linear electron flow and 2 cyclic electron flow (CEF) pathways around PSI (CEF-PSI). PROTON GRADIENT REGULATION 5 (PGR5)-dependent CEF-PSI is thought to be the major CEF-PSI pathway and an important regulator of photosynthetic electron transfer. Antimycin A (AA) is commonly recognized as an inhibitor of PGR5-dependent CEF-PSI in photosynthesis.

D139N mutation of PsbP enhances the oxygen-evolving activity of photosystem II through stabilized binding of a chloride ion.

Photosystem II (PSII) is a multisubunit membrane protein complex that catalyzes light-driven oxidation of water to molecular oxygen. The chloride ion (Cl) has long been known as an essential cofactor for oxygen evolution by PSII, and two Cl ions (Cl-1 and Cl-2) have been found to specifically bind near the MnCaO cluster within the oxygen-evolving center (OEC). However, despite intensive studies on these Cl ions, little is known about the function of Cl-2, the Cl ion that is associated with the backbone nitrogens of D1-Asn338, D1-Phe339, and CP43-Glu354.

Binding and functions of the two chloride ions in the oxygen-evolving center of photosystem II.

Light-driven water oxidation in photosynthesis occurs at the oxygen-evolving center (OEC) of photosystem II (PSII). Chloride ions (Cl) are essential for oxygen evolution by PSII, and two Cl ions have been found to specifically bind near the MnCaO cluster in the OEC. The retention of these Cl ions within the OEC is critically supported by some of the membrane-extrinsic subunits of PSII.