Photosystem I (PSI) is a multi-subunit integral pigment-protein complex that performs light-driven electron transfer from plastocyanin to ferredoxin in the thylakoid membrane of oxygenic photoautotrophs. In order to achieve the optimal photosynthetic performance under ambient irradiance, the absorption cross section of PSI is extended by means of peripheral antenna complexes. In eukaryotes, this role is played mostly by the pigment-protein complexes of the LHC family. The structure of the PSI-antenna supercomplexes has been relatively well understood in organisms harboring the primary plastid: red algae, green algae and plants. The secondary endosymbiotic algae, despite their major ecological importance, have so far received less attention. Here we report a detailed structural analysis of the antenna-PSI association in the stramenopile alga Nannochloropsis oceanica (Eustigmatophyceae). Several types of PSI-antenna assemblies are identified allowing for identification of antenna docking sites on the PSI core. Instances of departure of the stramenopile system from the red algal model of PSI-Lhcr structure are recorded, and evolutionary implications of these observations are discussed.

• Klíčová slova
• Electron microscopy, Light-harvesting complex, Nannochloropsis, Photosystem I, Stramenopila,
• MeSH
• fotosystém I (proteinový komplex) metabolismus   MeSH
• plastidy metabolismus   MeSH
• Rhodophyta metabolismus   MeSH
• spektrofotometrie ultrafialová MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fotosystém I (proteinový komplex) MeSH

Photosynthetic carbon fixation by Chromophytes is one of the significant components of a carbon cycle on the Earth. Their photosynthetic apparatus is different in pigment composition from that of green plants and algae. In this work we report structural maps of photosystem I, photosystem II and light harvesting antenna complexes isolated from a soil chromophytic alga Xanthonema debile (class Xanthophyceae). Electron microscopy of negatively stained preparations followed by single particle analysis revealed that the overall structure of Xanthophytes' PSI and PSII complexes is similar to that known from higher plants or algae. Averaged top-view projections of Xanthophytes' light harvesting antenna complexes (XLH) showed two groups of particles. Smaller ones that correspond to a trimeric form of XLH, bigger particles resemble higher oligomeric form of XLH.

• MeSH
• chlorofyl analýza   metabolismus   MeSH
• elektronová mikroskopie MeSH
• fluorescenční spektrometrie MeSH
• fotosyntéza MeSH
• fotosystém I (proteinový komplex) chemie   ultrastruktura   MeSH
• fotosystém II (proteinový komplex) chemie   ultrastruktura   MeSH
• Heterokontophyta chemie   ultrastruktura   MeSH
• multimerizace proteinu MeSH
• půda MeSH
• půdní mikrobiologie MeSH
• světlosběrné proteinové komplexy chemie   ultrastruktura   MeSH
• tylakoidy chemie   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorofyl MeSH
• fotosystém I (proteinový komplex) MeSH
• fotosystém II (proteinový komplex) MeSH
• fucoxanthin-, chlorophyll a-c-containing protein MeSH Prohlížeč
• půda MeSH
• světlosběrné proteinové komplexy MeSH