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Publication Abstract from PubMed

Prasiola crispa, an aerial green alga, forms layered colonies under the severe terrestrial conditions of Antarctica. Since only far-red light is available at a deep layer of the colony, P. crispa has evolved a molecular system for photosystem II (PSII) excitation using far-red light with uphill energy transfer. However, the molecular basis underlying this system remains elusive. Here, we purified a light-harvesting chlorophyll (Chl)-binding protein complex from P. crispa (Pc-frLHC) that excites PSII with far-red light and revealed its ring-shaped structure with undecameric 11-fold symmetry at 3.13 A resolution. The primary structure suggests that Pc-frLHC evolved from LHCI rather than LHCII. The circular arrangement of the Pc-frLHC subunits is unique among eukaryote LHCs and forms unprecedented Chl pentamers at every subunit‒subunit interface near the excitation energy exit sites. The Chl pentamers probably contribute to far-red light absorption. Pc-frLHC's unique Chl arrangement likely promotes PSII excitation with entropy-driven uphill excitation energy transfer.

Uphill energy transfer mechanism for photosynthesis in an Antarctic alga.,Kosugi M, Kawasaki M, Shibata Y, Hara K, Takaichi S, Moriya T, Adachi N, Kamei Y, Kashino Y, Kudoh S, Koike H, Senda T Nat Commun. 2023 Feb 15;14(1):730. doi: 10.1038/s41467-023-36245-1. PMID:36792917^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.