title: Efficient light harvesting in a dark, hot, acidic environment: the structure and function of PSI-LHCI from Galdieria sulphuraria.
abstract: Photosystem I-light harvesting complex I (PSI-LHCI) was isolated from the thermoacidophilic red alga Galdieria sulphuraria, and its structure, composition, and light-harvesting function were characterized by electron microscopy, mass spectrometry, and ultrafast optical spectroscopy. The results show that Galdieria PSI is a monomer with core features similar to those of PSI from green algae, but with significant differences in shape and size. A comparison with the crystal structure of higher plant (pea) PSI-LHCI indicates that Galdieria PSI binds seven to nine light-harvesting proteins. Results from ultrafast optical spectroscopy show that the functional coupling of the LHCI proteins to the PSI core is tighter than in other eukaryotic PSI-LHCI systems reported thus far. This tight coupling helps Galdieria perform efficient light harvesting under the low-light conditions present in its natural endolithic habitat.
authors.affiliation: Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, USA.
authors.forename: Balakumar
authors.initials: B
authors.lastname: Thangaraj
authors.forename: Craig C
authors.initials: CC
authors.lastname: Jolley
authors.forename: Iosifina
authors.initials: I
authors.lastname: Sarrou
authors.forename: Jelle B
authors.initials: JB
authors.lastname: Bultema
authors.forename: Jason
authors.initials: J
authors.lastname: Greyslak
authors.forename: Julian P
authors.initials: JP
authors.lastname: Whitelegge
authors.forename: Su
authors.initials: S
authors.lastname: Lin
authors.forename: Roman
authors.initials: R
authors.lastname: Kouřil
authors.forename: Rajagopal
authors.initials: R
authors.lastname: Subramanyam
authors.forename: Egbert J
authors.initials: EJ
authors.lastname: Boekema
authors.forename: Petra
authors.initials: P
authors.lastname: Fromme
mesh_terms: D000143:Acids; D000595:Amino Acid Sequence; D016825:Chlamydomonas reinhardtii; D002853:Chromatography, Liquid; D003624:Darkness; D004777:Environment; D006358:Hot Temperature; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D000461:Rhodophyta / Q000378:metabolism* / Q000648:ultrastructure; D013050:Spectrometry, Fluorescence
chemical_list: D000143:Acids; D045342:Light-Harvesting Protein Complexes; D010455:Peptides; D045331:Photosystem I Protein Complex