Low-potential cytochrome c that plays a role in the oxygen-evolving complex of photosystem II (PSII). Required for normal function or stabilization of PSII. Extrinsic protein associated with PSII that enhances oxygen evolution. Binds 1 heme c group covalently per subunit. The cyanobacterial oxygen-evolving complex is composed of PsbO, PsbP, PsbQ, PsbV and PsbU. Associated with photosystem II at the lumenal side of the thylakoid membrane. Cells show decreased but not abolished level of PSII and photoautotrophic growth. Belongs to the cytochrome c family. PsbV subfamily. Truncated N-terminus.