PSI-FCPI of the diatom Thalassiosira pseudonana CCMP1335
Ontology highlight
ABSTRACT:
SUBMITTER: Jian-Ren Shen
PROVIDER: EMPIAR-12142 | biostudies-other |
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Diatom is an important group of marine algae and contributes to around 20% of the global photosynthetic carbon fixation. Photosystem I (PSI) of diatoms is associated with a large number of fucoxanthin-chlorophyll a/c proteins (FCPIs). We report the structure of PSI-FCPI from a diatom Chaetoceros gracilis at 2.38 Å resolution by single-particle cryo-electron microscopy. PSI-FCPI is a monomeric supercomplex consisting of 12 core and 24 antenna subunits (FCPIs), and 326 chlorophylls a, 34 chlorophylls c, 102 fucoxanthins, 35 diadinoxanthins, 18 β-carotenes and some electron transfer cofactors. Two subunits designated PsaR and PsaS were found in the core, whereas several subunits were lost. The large number of pigments constitute a unique and huge network ensuring efficient energy harvesting, transfer and dissipation. These results provide a firm structural basis for unraveling the mechanisms of light-energy harvesting, transfer and quenching in the diatom PSI-FCPI, and also important clues to evolutionary changes of PSI-LHCI.
| S-EPMC7545214 | biostudies-literature
Project description:Approximately 65% of PSI structures report some type of ligand(s) that is bound in the crystal structure. Here, a description is given of how such ligands are handled and analyzed at the JCSG and a survey of the types, variety and frequency of ligands that are observed in the PSI structures is also compiled and analyzed, including illustrations of how these bound ligands have provided functional clues for annotation of proteins with little or no previous experimental characterization. Furthermore, a web server was developed as a tool to mine and analyze the PSI structures for bound ligands and other identifying features.
| S-EPMC2954221 | biostudies-literature
Project description:Chlamydomonas reinhardtii PSI-Cyt b6f complexes from sucrose density gradient fractions were identified by western blot and SMF spectroscopy, but showed high heterogeneity, as evident from the multiple bands present in the Coomassie stained SDS gel and original EM micrographs. Therefore potential PSI-Cyt b6f supercomplexes were enriched by a subsequent PsaA HisTag purification step. Only this additional enrichment enabled the identification of novel PSI supercomplexes, although the sample remained far from being homogeneous. This dataset describes the quantitative mass spectrometric analysis of the enriched PSI supercomplex fraction in comparison to unpurified samples using metabolic 15N labeling.
2018-10-03 | PXD008857 | Pride
Project description:Pseudouridine (Ψ) is known for decades, but its flexibility in base-pairing remains unclear. This study engineers artificial box H/ACA guide RNAs to direct pseudouridylation at the uridine of a premature termination codon (PTC; UAA, UAG, or UGA) within an intron-less mRNA and U36 of the anticodon of a matching tRNA in yeast and human cells. Targeted pseudouridylation leads to the formation of a Ψ-Ψ codon-anticodon pair, which, together with the other two Watson-Crick base pairs in the codon-anticodon duplex, significantly improves codon-anticodon recognition, robustly promoting PTC read-through. The intron-less mRNA level remains unchanged with or without guide RNAs. Additionally, pseudouridylation does not impact tRNA stability or charging. Our results show that nonsense suppression is promoted by the high affinity of the Ψ-Ψ pair, which is verified by melting curve analysis. This work has identified an unusual Ψ-Ψ base pair, which contributes significantly to codon-anticodon recognition and translational recoding.
2025-06-20 | GSE299290 | GEO
Project description:The [PSI(+)] prion is the aggregated self-propagating form of the Sup35 protein from the yeast Saccharomyces cerevisiae. Aggregates of Sup35 in [PSI(+)] cells exist in different heritable conformations, called "variants," and they are composed of detergent-resistant Sup35 polymers, which may be closely associated with themselves, other proteins, or both. Here, we report that disassembly of the aggregates into individual Sup35 polymers and non-Sup35 components increases their infectivity while retaining their variant specificity, showing that variant-specific [PSI(+)] infection can be transmitted by Sup35 polymers alone. Morphological analysis revealed that Sup35 isolated from [PSI(+)] yeast has the appearance of short barrels, and bundles, which seem to be composed of barrels. We show that the major components of two different variants of [PSI(+)] are interacting infectious Sup35 polymers and Ssa1/2. Using a candidate approach, we detected Hsp104, Ssb1/2, Sis1, Sse1, Ydj1, and Sla2 among minor components of the aggregates. We demonstrate that Ssa1/2 efficiently binds to the prion domain of Sup35 in [PSI(+)] cells, but that it interacts poorly with the nonaggregated Sup35 found in [psi(-)] cells. Hsp104, Sis1, and Sse1 interact preferentially with the prion versus nonprion form of Sup35, whereas Sla2 and Ssb1/2 interact with both forms of Sup35 with similar efficiency.
| S-EPMC2397312 | biostudies-literature
Project description:Differences in the clinical pathology of mammalian prion diseases reflect distinct heritable conformations of aggregated PrP proteins, called prion strains. Here, using the yeast [PSI(+) ] prion, we examine the de novo establishment of prion strains (called variants in yeast). The [PSI(+) ] prion protein, Sup35, is efficiently induced to take on numerous prion variant conformations following transient overexpression of Sup35 in the presence of another prion, e.g. [PIN(+) ]. One hypothesis is that the first [PSI(+) ] prion seed to arise in a cell causes propagation of only that seed's variant, but that different variants could be initiated in different cells. However, we now show that even within a single cell, Sup35 retains the potential to fold into more than one variant type. When individual cells segregating different [PSI(+) ] variants were followed in pedigrees, establishment of a single variant phenotype generally occurred in daughters, granddaughters or great-granddaughters - but in 5% of the pedigrees cells continued to segregate multiple variants indefinitely. The data are consistent with the idea that many newly formed prions go through a maturation phase before they reach a single specific variant conformation. These findings may be relevant to mammalian PrP prion strain establishment and adaptation.
| S-EPMC3543502 | biostudies-literature