[PSI(+)] is a prion of the essential translation termination factor Sup35p. Although mammalian prion infections are uniformly fatal, commonly studied [PSI(+)] variants do not impair growth, leading to suggestions that [PSI(+)] may protect against stress conditions. We report here that over half of [PSI(+)] variants are sick or lethal. These "killer [PSI(+)]s" are compatible with cell growth onl...

A Chlamydomonas reinhardtii mutant lacking CGL71, a thylakoid membrane protein previously shown to be involved in photosystem I (PSI) accumulation, exhibited photosensitivity and highly reduced abundance of PSI under photoheterotrophic conditions. Remarkably, the PSI content of this mutant declined to nearly undetectable levels under dark, oxic conditions, demonstrating that reduced PSI accumul...

Photosystem I (PSI) achieves photo-induced charge separation with outstanding internal quantum efficiency and has been used to improve the performance of various photoelectrochemical systems. Herein, we describe a fast and versatile technique to assemble composite films containing PSI and a chosen intrinsically conductive polymer (ICP). A mixture of PSI and a Friedel-Crafts catalyst (FeCl3) is ...

[PSI+] is a protein-based heritable phenotype of the yeast Saccharomyces cerevisiae which reflects the prion-like behaviour of the endogenous Sup35p protein release factor. [PSI+] strains exhibit a marked decrease in translation termination efficiency, which permits decoding of translation termination signals and, presumably, the production of abnormally extended polypeptides. We have examined ...

Shade-establishing plants growing in the forest understory are exposed to constant high light or fluctuating light when gaps are created by fallen trees. Our previous studies indicate that photosystem I (PSI) is sensitive to constant high light in shade-establishing tree species, however, the effects of fluctuating light on PSI and photosystem II (PSII) in shade-establishing species are little ...

The yeast [PSI+] prion is an epigenetic modifier of translation termination fidelity that causes nonsense suppression. The prion [PSI+] forms when the translation termination factor Sup35p adopts a self-propagating conformation. The presence of the [PSI+] prion modulates survivability in a variety of growth conditions. Nonsense suppression is essential for many [PSI+]-mediated phenotypes, but m...

Photosystem I (PSI) is a photochemically active membrane protein complex that functions at the reducing site of the photosynthetic electron-transfer chain as plastocyanin-ferredoxin oxidoreductase. PsaE, a peripheral subunit of the PSI complex, plays an important role in the function of PSI. PsaE is involved in the docking of ferredoxin/flavodoxin to the PSI complex and also participates in the...

We have used a strategy for colocalization of Psi (Psi)-tethered ribozymes and targets to demonstrate that Psi sequences are capable of specific interaction in the cytoplasm of both packaging and nonpackaging cells. These results indicate that current in vitro dimerization models may have in vivo counterparts. The methodology used may be applied to further genetic analyses on Psi domain interac...