title: Involvement of the Lhcx protein Fcp6 of the diatom Cyclotella meneghiniana in the macro-organisation and structural flexibility of thylakoid membranes.
abstract: Diatoms possess special light-harvesting proteins involved in the photoprotection mechanism called non-photochemical quenching (NPQ). These Lhcx proteins were shown to be subunits of trimeric fucoxanthin-chlorophyll complexes (FCPa) in centric diatoms, but their mode of action is still unclear. Here we investigated the influence of Fcp6, an orthologue to Lhcx1 of Thalassiosira pseudonana in the diatom Cyclotella meneghiniana, by reducing its amount using an antisense approach. Whereas the pigment interactions inside FCPa were not influenced by the presence or absence of Fcp6, as demonstrated by unaltered spectra of circular dichroism, changes could be observed on the level of thylakoids and cells in the mutants compared to WT. This fits to recent models of NPQ in diatoms, where FCP aggregation or supramolecular reorganisation is thought to be a major feature. Thus, Fcp6 (Lhcx1) appears to alter pigment-pigment interactions inside the aggregates, but not inside (un-aggregated) FCPa itself.
authors.affiliation: Institute of Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany.
authors.forename: Artur
authors.initials: A
authors.lastname: Ghazaryan
authors.affiliation: Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary.
authors.forename: Parveen
authors.initials: P
authors.lastname: Akhtar
authors.affiliation: Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary.
authors.forename: Győző
authors.initials: G
authors.lastname: Garab
authors.affiliation: Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary.
authors.forename: Petar H
authors.initials: PH
authors.lastname: Lambrev
authors.affiliation: Institute of Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany. Electronic address: C.Buechel@bio.uni-frankfurt.de.
authors.forename: Claudia
authors.initials: C
authors.lastname: Büchel
mesh_terms: D002942:Circular Dichroism; D017377:Diatoms / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000502:physiology*; D066329:Protein Aggregates; D020524:Thylakoids / Q000737:chemistry*
chemical_list: D045342:Light-Harvesting Protein Complexes; D066329:Protein Aggregates; C088752:fucoxanthin-, chlorophyll a-c-containing protein
keywords: Anisotropic circular dichroism; FCPa; LHCSR; Lhcx1; Non-photochemical quenching