Low-potential cytochrome c that plays a role in the oxygen-evolving complex of photosystem II. Binds 1 heme c group covalently per subunit. The oxygen-evolving complex may be composed of psbO, psbQ', psbV and psbU. Associated with photosystem II at the lumenal side of the thylakoid membrane. Belongs to the cytochrome c family. PsbV subfamily.