biostudies-literatureZhang SChinese Academy of SciencesChinese Academy of Sciences (CAS)National Natural Science Foundation of ChinaNational Natural Science Foundation of China (National Science Foundation of China)560https://www.ebi.ac.uk/biostudies/studies/S-EPMC11088674biostudies-literatureUnknown7(1)Photosynthetic cryptophytes are eukaryotic algae that utilize membrane-embedded chlorophyll a/c binding proteins (CACs) and lumen-localized phycobiliproteins (PBPs) as their light-harvesting antennae. Cryptophytes go through logarithmic and stationary growth phases, and may adjust their light-harvesting capability according to their particular growth state. How cryptophytes change the type/arrangement of the photosynthetic antenna proteins to regulate their light-harvesting remains unknown. Here we solve four structures of cryptophyte photosystem I (PSI) bound with CACs that show the rearrangement of CACs at different growth phases. We identify a cryptophyte-unique protein, PsaQ, which harbors two chlorophyll molecules. PsaQ specifically binds to the lumenal region of PSI during logarithmiCommunications biologyGrowth phase-dependent reorganization of cryptophyte photosystem I antennae.PMC1108867431930064XDB37020101Si LAn XZhang SSu XLi MZhao XfalseGrowth phase-dependent reorganization of cryptophyte photosystem I antennae.Photosynthetic cryptophytes are eukaryotic algae that utilize membrane-embedded chlorophyll a/c binding proteins (CACs) and lumen-localized phycobiliproteins (PBPs) as their light-harvesting antennae. Cryptophytes go through logarithmic and stationary growth phases, and may adjust their light-harvesting capability according to their particular growth state. How cryptophytes change the type/arrangement of the photosynthetic antenna proteins to regulate their light-harvesting remains unknown. Here we solve four structures of cryptophyte photosystem I (PSI) bound with CACs that show the rearrangement of CACs at different growth phases. We identify a cryptophyte-unique protein, PsaQ, which harbors two chlorophyll molecules. PsaQ specifically binds to the lumenal region of PSI during logarithmi2024-01-01T00:00:00Z2024 May2026-06-02T08:17:48.449Z2026-05-26T03:07:24.476ZS-EPMC110886743873481910.1038/s42003-024-06268-5