title: First solid-state NMR analysis of uniformly ¹³C-enriched major light-harvesting complexes from Chlamydomonas reinhardtii and identification of protein and cofactor spin clusters.
abstract: The light-harvesting complex II (LHCII) is the main component of the antenna system of plants and green algae and plays a major role in the capture of sun light for photosynthesis. The LHCII complexes have also been proposed to play a key role in the optimization of photosynthetic efficiency through the process of state 1-state 2 transitions and are involved in down-regulation of photosynthesis under excess light by energy dissipation through non-photochemical quenching (NPQ). We present here the first solid-state magic-angle spinning (MAS) NMR data of the major light-harvesting complex (LHCII) of Chlamydomonas reinhardtii, a eukaryotic green alga. We are able to identify nuclear spin clusters of the protein and of its associated chlorophyll pigments in ¹³C-¹³C dipolar homonuclear correlation spectra on a uniformly ¹³C-labeled sample. In particular, we were able to resolve several chlorophyll 13¹ carbon resonances that are sensitive to hydrogen bonding to the 13¹-keto carbonyl group. The data show that ¹³C NMR signals of the pigments and protein sites are well resolved, thus paving the way to study possible structural reorganization processes involved in light-harvesting regulation through MAS solid-state NMR.
authors.affiliation: Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands. apandit@few.vu.nl
authors.forename: Anjali
authors.initials: A
authors.lastname: Pandit
authors.forename: Tomas
authors.initials: T
authors.lastname: Morosinotto
authors.forename: Michael
authors.initials: M
authors.lastname: Reus
authors.forename: Alfred R
authors.initials: AR
authors.lastname: Holzwarth
authors.forename: Roberto
authors.initials: R
authors.lastname: Bassi
authors.forename: Huub J M
authors.initials: HJ
authors.lastname: de Groot
mesh_terms: D000595:Amino Acid Sequence; D016825:Chlamydomonas reinhardtii / Q000201:enzymology*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment
chemical_list: D045342:Light-Harvesting Protein Complexes