Pigment structure in the light-harvesting protein of the siphonous green alga Codium fragile.

The siphonaxanthin-siphonein-chlorophyll-a/b-binding protein (SCP), a trimeric light-harvesting complex isolated from photosystem II of the siphonous green alga Codium fragile, binds the carotenoid siphonaxanthin (Sx) and/or its ester siphonein in place of lutein, in addition to chlorophylls a/b and neoxanthin. SCP exhibits a higher content of chlorophyll b (Chl-b) than its counterpart in green plants, light-harvesting complex II (LHCII), increasing the relative absorption of blue-green light for photosynthesis. Using low temperature absorption and resonance Raman spectroscopies, we reveal the presence of two non-equivalent Sx molecules in SCP, and assign their absorption peaks at 501 and 535 nm. The red-absorbing Sx population exhibits a significant distortion that is reminiscent of lutein 2 in trimeric LHCII. Unexpected enhancement of the Raman modes of Chls-b in SCP allows an unequivocal description of seven to nine non-equivalent Chls-b, and six distinct Chl-a populations in this protein. Copyright © 2021 Elsevier B.V. All rights reserved.

Citation

Simona Streckaite, Manuel J Llansola-Portoles, Andrew A Pascal, Cristian Ilioaia, Andrew Gall, Soichiro Seki, Ritsuko Fujii, Bruno Robert. Pigment structure in the light-harvesting protein of the siphonous green alga Codium fragile. Biochimica et biophysica acta. Bioenergetics. 2021 May 01;1862(5):148384

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PMID: 33545114

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