What would be most likely to happen if some of the proteins in one of the photosystems were to change shape due to a drop in cell pH?

Plants use proteins to promote cell growth and repair damaged tissue, much like humans do. During the light stage of photosynthesis, proteins containing copper and iron help facilitate the transporting of electrons between water and other key molecules.
The water in the plant is an aqueous solution that acts as a solvent during photosynthesis, and as such, it has certain levels of acidity and basicity measured through a logarithmic scale called pH (potential of hydrogen).
A chemical called NADPH (nicotinamide adenine dinucleotide phosphate hydrogen), which is critical to energy creation in the plant, is a product generated during the first stage of photosynthesis that is later used by the plant to fuel essential reactions during the second stage.
The first stage of photosynthesis, when NADPH is created, involves two sets of molecules—photosystem I and II—which absorb sunlight, convert it to chemical energy, and transfer it to electrons.
However, various outside factors can cause a plant's pH level to drop during photosynthesis, from the alkalinity in the water supply to respiration and decomposition.
As a plant's pH level drops, it can alter the shape of proteins within either of the two photosystems and cause a decrease in the formation of NADPH, thus adversely affecting efficient photosynthesis, and cause an increase of another chemical called ATP (adenosine triphosphate).
ATP is a nucleotide molecule, containing a sugar called ribose, that stores and transfers energy and is also crucial to the synthesizing of nucleic acids. As pH levels drop from a neutral level, the additional ATP molecule tries to ensure the plant has sufficient levels of energy to survive.
https://sciencing.com/nadph-photosynthesis-5799755.html

https://www.worldofmolecules.com/life/atp.htm