The thylakoid membrane proteome of two marine diatoms outlines both diatom-specific and species-specific features of the photosynthetic machinery.
The thylakoid membrane of photoautotrophic organisms contains the main components of the photosynthetic electron transport chain. Detailed proteome maps of the thylakoid protein complexes of two marine diatoms, Thalassiosira pseudonana and Phaeodactylum tricornutum, were created by means of two-dimensional blue native (BN)/SDS-PAGE coupled with mass spectrometry analysis. One novel diatom-specific photosystem I (PS I)-associated protein was identified. A second plastid-targeted protein with possible PS I interaction was discovered to be restricted to the centric diatom species T. pseudonana. PGR5/PGRL homologues were found to be the only protein components of PS I-mediated cyclic electron transport common to both species. For the first time, evidence for a possible PS I localization of LI818-like light harvesting proteins (Lhcx) is presented. This study also advances the current knowledge on the light harvesting antenna composition and Lhcx expression in T. pseudonana on the protein level and presents details on the molecular distribution of Lhcx in diatoms. Above mentioned proteins and several others with unknown function provide a broad basis for further mutagenesis analysis, aiming toward further understanding of the composition and function of the photosynthetic apparatus of diatoms. The proteomics approach of this study further served as a tool to confirm and improve genome-derived protein models.
Department of Biochemistry and Food Chemistry, Molecular Plant Biology, Tykistökatu 6A, FI-20520, University of Turku, Finland.
Irina
I
Grouneva
Anne
A
Rokka
Eva-Mari
EM
Aro
D000595:Amino Acid Sequence; D025222:Chloroplast Proton-Translocating ATPases / Q000737:chemistry; D045346:Cytochrome b6f Complex / Q000737:chemistry; D030562:Databases, Protein; D017377:Diatoms / Q000737:chemistry*; D004579:Electron Transport; D004591:Electrophoresis, Polyacrylamide Gel; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry; D008969:Molecular Sequence Data; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000737:chemistry; D018087:Plastids / Q000737:chemistry; D020543:Proteome / Q000032:analysis / Q000737:chemistry*; D016415:Sequence Alignment; D012995:Solubility; D013045:Species Specificity; D020524:Thylakoids / Q000737:chemistry*; D024341:Xanthophylls / Q000737:chemistry
D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D020543:Proteome; D024341:Xanthophylls; C025164:fucoxanthin; D045346:Cytochrome b6f Complex; D025222:Chloroplast Proton-Translocating ATPases