title: The trade-off between the light-harvesting and photoprotective functions of fucoxanthin-chlorophyll proteins dominates light acclimation in Emiliania huxleyi (clone CCMP 1516).
abstract: Mechanistic understanding of the costs and benefits of photoacclimation requires knowledge of how photophysiology is affected by changes in the molecular structure of the chloroplast. We tested the hypothesis that changes in the light dependencies of photosynthesis, nonphotochemical quenching and PSII photoinactivation arises from changes in the abundances of chloroplast proteins in Emiliania huxleyi strain CCMP 1516 grown at 30 (Low Light; LL) and 1000 (High Light; HL) μmol photons m(-2) s(-1) photon flux densities. Carbon-specific light-saturated gross photosynthesis rates were not significantly different between cells acclimated to LL and HL. Acclimation to LL benefited cells by increasing biomass-specific light absorption and gross photosynthesis rates under low light, whereas acclimation to HL benefited cells by reducing the rate of photoinactivation of PSII under high light. Differences in the relative abundances of proteins assigned to light-harvesting (Lhcf), photoprotection (LI818-like), and the photosystem II (PSII) core complex accompanied differences in photophysiology: specifically, Lhcf:PSII was greater under LL, whereas LI818:PSII was greater in HL. Thus, photoacclimation in E. huxleyi involved a trade-off amongst the characteristics of light absorption and photoprotection, which could be attributed to changes in the abundance and composition of proteins in the light-harvesting antenna of PSII.
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors.forename: Boyd A
authors.initials: BA
authors.lastname: McKew
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors.forename: Phillip
authors.initials: P
authors.lastname: Davey
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors.forename: Stewart J
authors.initials: SJ
authors.lastname: Finch
authors.affiliation: National Oceanography Centre, University of Southampton, European Way, Southampton, SO14 3ZH, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Hopkins
authors.affiliation: J. Craig Venter Institute, San Diego, CA, 92121, USA.
authors.forename: Stephane C
authors.initials: SC
authors.lastname: Lefebvre
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors.forename: Metodi V
authors.initials: MV
authors.lastname: Metodiev
authors.affiliation: CTG Ltd, 55 Central Avenue, West Molesey, KT8 2QZ, UK.
authors.forename: Kevin
authors.initials: K
authors.lastname: Oxborough
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Raines
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors.forename: Tracy
authors.initials: T
authors.lastname: Lawson
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Geider
mesh_terms: D000064:Acclimatization; D002734:Chlorophyll / Q000378:metabolism; D061146:Chlorophyll Binding Proteins / Q000378:metabolism*; D058087:Haptophyta / Q000378:metabolism / Q000502:physiology*; D008027:Light; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D061146:Chlorophyll Binding Proteins; D045332:Photosystem II Protein Complex; D024341:Xanthophylls; C025164:fucoxanthin; D002734:Chlorophyll
keywords: Emiliania huxleyi; gross photosynthesis; light acclimation; light harvesting; nonphotochemical quenching; photoinactivation; photoinhibition