EMD-32588

Single-particle
2.8 Å
EMD-32588 Deposition: 13/01/2022
Map released: 23/11/2022
Last modified: 26/06/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-32588

The Cryo-EM structure of siphonaxanthin chlorophyll a/b type light-harvesting complex II

EMD-32588

Single-particle
2.8 Å
EMD-32588 Deposition: 13/01/2022
Map released: 23/11/2022
Last modified: 26/06/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Codium fragile
Sample: siphonaxanthin chlorophyll a/b-type light-harvesting complex II
Fitted models: 7wlm (Avg. Q-score: 0.649)

Deposition Authors: Seki S , Nakaniwa T, Castro-Hartmann P, Sader K, Kawamoto A , Tanaka H, Qian P, Kurisu G , Fujii R
Structural insights into blue-green light utilization by marine green algal light harvesting complex II at 2.78 angstrom.
Seki S , Nakaniwa T, Castro-Hartmann P, Sader K, Kawamoto A , Tanaka H, Qian P, Kurisu G , Fujii R
(2022) Bba Adv , 2 , 100064 - 100064
PUBMED: 37082593
DOI: doi:10.1016/j.bbadva.2022.100064
ISSN: 2667-1603
Abstract:
Light-harvesting complex II (LHCII) present in plants and green algae absorbs solar energy to promote photochemical reactions. A marine green macroalga, Codium fragile, exhibits the unique characteristic of absorbing blue-green light from the sun during photochemical reactions while being underwater owing to the presence of pigment-altered LHCII called siphonaxanthin-chlorophyll a/b-binding protein (SCP). In this study, we determined the structure of SCP at a resolution of 2.78 Å using cryogenic electron microscopy. SCP has a trimeric structure, wherein each monomer containing two lutein and two chlorophyll a molecules in the plant-type LHCII are replaced by siphonaxanthin and its ester and two chlorophyll b molecules, respectively. Siphonaxanthin occupies the binding site in SCP having a polarity in the trimeric inner core, and exhibits a distorted conjugated chain comprising a carbonyl group hydrogen bonded to a cysteine residue of apoprotein. These features suggest that the siphonaxanthin molecule is responsible for the characteristic green absorption of SCP. The replaced chlorophyll b molecules extend the region of the stromal side chlorophyll b cluster, spanning two adjacent monomers.