Concise Biosynthesis of Tropone-Containing Spiromaterpenes by a Sesquiterpene Cyclase and a Multifunctional P450 from a Deep-Sea-Derived Spiromastix sp. Fungus.

Spiromaterpenes are a group of rare tropone-containing sesquiterpenes with antineuroinflammatory activity. Herein, we elucidate their biosynthetic pathway in a deep-sea-derived Spiromastix sp. fungus by heterologous expression, biochemical characterization, and incubation experiments. The sesquiterpene cyclase SptA was first characterized to catalyze the production of guaia-1(5),6-diene, and a multifunctional cytochrome P450 catalyzed the tropone ring formation. These results provide important clues for the rational mining of bioactive guaiane-type sesquiterpenes and expand the repertoire of P450 activities to synthesize unique building blocks of natural products.

SenseCam reminiscence and action recall in memory-unimpaired people.

Case studies of memory-impaired individuals consistently show that reminiscing with SenseCam images enhances event recall. This exploratory study examined whether a similar benefit would occur for the consolidation of memories in memory-unimpaired people. We tested delayed recall for atypical actions observed on a lengthy walk. Participants used SenseCam, a diary, or no external memory aid while walking, followed by reminiscence with SenseCam images, diary entries, or no aid, either alone (self-reminiscence) or with the experimenter (social reminiscence). One week later, when tested without SenseCam images or diary entries, prior social reminiscence produced greater recall than self-reminiscence, but there were no differences between memory aid conditions for action free recall or action order recall. When methodological variables were controlled, there was no recall advantage for SenseCam reminiscence with memory-unimpaired participants. The case studies and present study differ in multiple ways, making direct comparisons problematic. SenseCam is a valuable aid to the memory impaired, but its mnemonic value for non-clinical populations remains to be determined.

Biosynthesis of Epipyrone A Reveals a Highly Specific Membrane-Bound Fungal C-Glycosyltransferase for Pyrone Galactosylation.

Epipyrone A is a unique C-galactosylated 4-hydroxy-2-pyrone derivative with an antifungal potential from the fungus Epicoccum nigrum. We elucidated its biosynthesis via heterologous expression and characterized an unprecedented membrane-bound pyrone C-glycosyltransferase biochemically. Molecular docking and mutagenesis experiments suggested a possible mechanism for the heterocyclic C-glycosylation and the importance of a transmembrane helix for its catalysis. These results expand the repertoire of C-glycosyltransferases and provide new insights into the formation of C-glycosides in fungi.