O‐Methyltransferase Is Shared between the Pentose Phosphate and Shikimate Pathways and Is Essential for Mycosporine‐Like Amino Acid Biosynthesis in Anabaena variabilis ATCC 29413

The parent core structure of mycosporine‐like amino acids (MAAs) is 4‐deoxygadusol, which, in cyanobacteria, is derived from conversion of the pentose phosphate pathway intermediate sedoheptulose 7‐phosphate by the enzymes 2‐epi‐5‐epivaliolone synthase (EVS) and O‐methyltransferase (OMT). Yet, deletion of the EVS gene from Anabaena variabilis ATCC 29413 was shown to have little effect on MAA production, thus suggesting that its biosynthesis is not exclusive to the pentose phosphate pathway. Herein, we report how, using pathway‐specific inhibitors, we demonstrated unequivocally that MAA biosynthesis occurs also via the shikimate pathway. In addition, complete in‐frame gene deletion of the OMT gene from A. variabilis ATCC 29413 reveals that, although biochemically distinct, the pentose phosphate and shikimate pathways are inextricably linked to MAA biosynthesis in this cyanobacterium. Furthermore, proteomic data reveal that the shikimate pathway is the predominate route for UV‐induced MAA biosynthesis.     

Redundant pathways of sunscreen biosynthesis in a cyanobacterium

Route of the sun block: according to empirical evidence, sun-screening mycosporine-like amino acids (MAAs) in Eukarya originate from the shikimic acid pathway, whereas in cyanobacteria, biosynthesis of the MAA shinorine reportedly occurs through the pentose phosphate pathway. However, gene deletion shows that the cyanobacterium Anabaena variabilis ATCC 29143 does not biosynthesise shinorine exclusively by this route.     

Review of sunscreen and the emergence of non-conventional absorbers and their applications in ultraviolet protection

Protection against ultraviolet (UV) radiation is the major function of sunscreen lotions and UV-protective coatings for vehicles, homes, equipment and clothing. Sunscreen formulations have been optimized to become protective over a broader spectrum of UV radiation and maintain greater photostability. They are comprised of organic and inorganic components that act as chemical and physical UV protectors, respectively. Some of the organic components are limited by their spectrum of protection and photostability. Studies using solid lipid nanoparticles, recently explored organic molecules, inorganic components and antioxidants attempt to further optimize UV protection. In this review, we examine traditional and emerging nanoparticle components and highlight novel ideas in UV protection which may provide pathways for future studies.     

Mycosporine-glutaminol-glucoside, a UV-absorbing compound of two Rhodotorula yeast species

High-performance liquid chromatography (HPLC), alone or in combination with mass spectrometry (MS), was used to screen the basidiomycetous yeasts Rhodotorula minuta and R. slooffiae isolated from lakes for the presence of UV-absorbing compounds. Mycosporine-glutaminol-glucoside (maximum absorption, 310 nm), a UV-photoprotective mycosporine known in terrestrial fungi, was the major UV-absorbing compound found in these species. This is the first identification of a mycosporine in yeasts. The presence of this compound seems to be a promising chemotaxonomical marker for yeast systematics.