Microbial sunscreens.
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ABSTRACT:
SUBMITTER: Siezen RJ
PROVIDER: S-EPMC3815790 | biostudies-literature | 2011 Jan
REPOSITORIES: biostudies-literature
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Project description:Mycosporine-like amino acids (MAAs) are a family of water-soluble and colorless secondary metabolites, with high extinction coefficients, that function as microbial sunscreens. MAAs share a cyclohexinimine chromophore that is diversified through amino acid substitutions and attachment of sugar moieties. The genetic and enzymatic bases for the chemical diversity of MAAs remain largely unexplored. Here we report a series of structurally distinct MAAs and evidence for an unusual branched biosynthetic pathway from a cyanobacterium isolated from lake sediment. We used a combination of high-resolution liquid chromatography-mass spectrometry (HR-LCMS) analysis and nuclear magnetic resonance (NMR) spectroscopy to identify diglycosylated-palythine-Ser (C22H36N2O15) as the dominant chemical variant in a series of MAAs from Nostoc sp. UHCC 0302 that contained either Ser or Thr. We obtained a complete 9.9 Mb genome sequence to gain insights into the genetic basis for the biosynthesis of these structurally distinct MAAs. We identified MAA biosynthetic genes encoded at two locations on the circular chromosome. Surprisingly, direct pathway cloning and heterologous expression of the complete mysABCJ 1 D 1 G 1 H biosynthetic gene cluster in Escherichia coli (E. coli) led to the production of 450 Da monoglycosylated-palythine-Thr (C18H30N2O11). We reconstructed combinations of the two distant biosynthetic gene clusters in refactored synthetic pathways and expressed them in the heterologous host. These results demonstrated that the MysD1 and MysD2 enzymes displayed a preference for Thr and Ser, respectively. Furthermore, one of the four glycosyltransferases identified, MysG1, was active in E. coli and catalysed the attachment of a hexose moiety to the palythine-Thr intermediate. Together these results provide the first insights into the enzymatic basis for glycosylation of MAAs and demonstrates how paralogous copies of the MysD enzymes allow the simultaneous biosynthesis of specific chemical variants to increase the structural variation in this family of microbial sunscreens.
| S-EPMC11378024 | biostudies-literature
Project description:Mycosporine-like amino acids (MAAs) are small, colorless, and water-soluble secondary metabolites. They have high molar extinction coefficients and a unique UV radiation absorption mechanism that make them effective sunscreens. Here we report the discovery of two structurally distinct MAAs from the lichen symbiont strain Nostoc sp. UHCC 0926. We identified these MAAs as aplysiapalythine E (C23H38N2O15) and tricore B (C34H53N4O15) using a combination of high-resolution liquid chromatography-mass spectrometry (HR-LCMS) analysis and nuclear magnetic resonance (NMR) spectroscopy. We obtained a 8.3 Mb complete genome sequence of Nostoc sp. UHCC 0926 to gain insights into the genetic basis for the biosynthesis of these two structural distinct MAAs. We identified MAA biosynthetic genes encoded in three separate locations of the genome. The organization of biosynthetic enzymes in Nostoc sp. UHCC 0926 necessitates a branched biosynthetic pathway to produce two structurally distinct MAAs. We detected the presence of such discontiguous MAA biosynthetic gene clusters in 12% of the publicly available complete cyanobacterial genomes. Bioinformatic analysis of public MAA biosynthetic gene clusters suggests that they are subject to rapid evolutionary processes resulting in highly plastic biosynthetic pathways that are responsible for the chemical diversity in this family of microbial sunscreens.
| S-EPMC10510106 | biostudies-literature
Project description:BackgroundWhile sunbathing of performing outdoor sport activities, sunscreens are important for protection of uncovered skin against ultraviolet (UV) radiation. However, perspiration negatively affects the performance of a sunscreen film by weakening its substantivity and uniformity through the activation of two mechanisms, namely sunscreen wash-off and sunscreen redistribution.Material and methodsWe used a perspiring skin simulator to investigate the effect of sunscreen formulation on its efficiency upon sweating. Specifically, we modified the sunscreen formulation by incorporating a hydrophobic film former and adding water-absorbing particles. Sunscreen performance before and after perspiration is assessed by in vitro sun protection factor measurements, direct detection of changes in the sunscreen distribution using UV reflectance imaging, and by coherent anti-Stokes Raman scattering (CARS) microscopy for microscopic characterization of the UV filter relocation.ResultsThe results show that incorporating a hydrophobic film former can decrease sunscreen wash-off due to sweating, while an excessive amount of film former might negatively affect the sunscreen distribution. The addition of water-absorbing particles, on the other hand, had either a negative or positive impact on the sunscreen substantivity, depending on the particle properties. While the addition of large water-absorbing particles appeared to increase sunscreen redistribution, smaller particles that could form a gel-like structure upon contact with water, appeared to change sunscreen wetting and sweat droplet spreading, thereby decreasing sunscreen wash-off and sunscreen redistribution.ConclusionsWe find that using a combination of hydrophobic film formers, which increase water resistance, and small water-absorbing particles, which change the wetting behavior, can make sunscreen formulations more sweat-resistant and less runny.
| S-EPMC9907632 | biostudies-literature
Project description:Ultraviolet (UV) radiation promotes the generation of reactive oxygen species (ROS) and nitrogen species (RNS), resulting in skin damage. Cosmetic industries have adopted a strategy to incorporate antioxidants in sunscreen formulations to prevent or minimize UV-induced oxidative damage, boost photoprotection effectiveness, and mitigate skin photoaging. Many antioxidants are naturally derived, mainly from terrestrial plants; however, marine organisms have been increasingly explored as a source of new potent antioxidant molecules. This work aims to characterize the frequency of the use of antioxidants in commercial sunscreens. Photoprotective formulations currently marketed in parapharmacies and pharmacies were analyzed with respect to the composition described on the label. As a result, pure compounds with antioxidant activity were found. The majority of sunscreen formulations contained antioxidants, with vitamin E and its derivatives the most frequent. A more thorough analysis of these antioxidants is also provided, unveiling the top antioxidant ingredients found in sunscreens. A critical appraisal of the scientific evidence regarding their effectiveness is also performed. In conclusion, this work provides an up-to-date overview of the use of antioxidants in commercial sunscreens for a better understanding of the advantages associated with their use in photoprotective formulations.
| S-EPMC9854756 | biostudies-literature
Project description:Lysobacter are ubiquitous environmental bacteria emerging as novel biocontrol agents and new sources of anti-infectives. So far, very little effort has been invested in the study of the biology of these Gram-negative gliding bacteria. Many Lysobacter species are characterized by their yellow-orange appearance. Using transposon mutagenesis, we identified a stand-alone polyketide synthase (PKS) gene cluster required for the pigment production in L. enzymogenes OH11. The yellow pigments were abolished in the "white" mutants generated by target-specific deletions of ketosynthase (KS), acyl carrier protein, or ketoreductase. Spectroscopic data suggested that the pigments belong to xanthomonadin-like aryl polyenes. Polyene-type polyketides are known to be biosynthesized by modular PKS (Type I), not by stand-alone PKS (Type II) which always contain the heterodimer KS-CLF (chain-length factor) as the key catalytic component. Remarkably, this aryl polyene PKS complex only contains the KS (ORF17), but not the CLF. Instead, a hypothetical protein (ORF16) is located immediately next to ORF17. ORF16-17 homologs are widespread in numerous uncharacterized microbial genomes, in which an ORF17 homolog is always accompanied by an ORF16 homolog. The deletion of ORF16 eliminated pigment production, and homology modeling suggested that ORF16 shares a structural similarity to the N-terminal half of CLF. A point-mutation of glutamine (Q166A) that is the conserved active site of known CLF abolished pigment production. The "white" mutants are significantly more sensitive to UV/visible light radiation or H2O2 treatment than the wild type. These results unveil the first example of Type II PKS-synthesized polyene pigments and show that the metabolites serve as Lysobacter "sunscreens" that are important for the survival of these ubiquitous environmental organisms.
| S-EPMC3691225 | biostudies-literature
Project description:One of the functions of placenta is to protect the fetus against harmful xenobiotics. Protective mechanisms of placenta are based on enzymes, e.g., antioxidant enzymes from the glutathione S-transferases group (GST) or human N-acetyltransferase 2 (NAT2). Many organic sunscreens are known to cross biological barriers-they are detected in mother's milk, semen, umbilical cord blood or placental tissues. Some organic sunscreens are able to cross the placenta and to interfere with fetal development; they are known or suspected endocrine disruptors or neurotoxins. In this study, 16 organic sunscreens were investigated in the context of their placenta permeability and interactions with gluthatione S-transferase and human N-acetyltransferase 2 enzymes present in the human placenta. Binary permeability models based on discriminant analysis and artificial neural networks proved that the majority of studied compounds are likely to cross the placenta by passive diffusion. Molecular docking analysis suggested that some sunscreens show stronger affinity for glutathione S-transferase and human N-acetyltransferase 2 that native ligands (glutathione and Coenzyme A for GST and NAT2, respectively)-it is therefore possible that they are able to reduce the enzyme's protective activity. It was established that sunscreens bind to the studied enzymes mainly by alkyl, hydrogen bonds, van der Waals, π-π, π-alkyl and π-sulfur interactions. To conclude, sunscreens may become stressors affecting humans by different mechanisms and at different stages of development.
| S-EPMC11728689 | biostudies-literature
Project description:BackgroundUV exposure continues to induce many health issues, though commercial sunscreens are available. Novel UV filters with high safety and efficacy are urgently needed. Metal-organic frameworks (MOFs) could be a suitable platform for UV filter development, due to their tunable optical, electrical, and photoelectric properties by precise controlled synthesis.ResultsHerein, four zinc-based MOFs with various bandgap energies were chose to investigate their optical behaviors and evaluate their possibility as sunscreens. Zeolitic imidazolate framework-8 (ZIF-8) was found to possess the highest and widest UV reflectance, thereby protecting against sunburn and DNA damage on mouse skin and even achieving a comparable or higher anti-UV efficacy relative to the commercially available UV filters, TiO2 or ZnO, on pig skin, a model that correlates well with human skin. Also, ZIF-8 exerted appealing characteristics for topical skin use with low radical production, low skin penetration, low toxicity, high transparency, and high stability.ConclusionThese results confirmed ZIF-8 could potentially be a safe and effective sunscreen surrogate for human, and MOFs could be a novel source to develop more effective and safe UV filters.
| S-EPMC8858458 | biostudies-literature
Project description:BackgroundMycosporine-like amino acids (MAAs), including shinorine and porphyra-334, are gaining attention as safe natural sunscreens. The production of MAAs has been achieved in diverse microbial hosts, including Saccharomyces cerevisiae. While S. cerevisiae is the most extensively studied model yeast, the oleaginous yeast Yarrowia lipolytica has emerged as a promising candidate for the synthesis of valuable products. In this study, we explored the potential of Y. lipolytica as a host for producing MAAs, utilizing its advantages such as a robust pentose phosphate pathway flux and versatile carbon source utilization.ResultsWe produced MAAs in Y. lipolytica by introducing the MAA biosynthetic genes from cyanobacteria Nostoc punctiforme and Anabaena variabilis. These genes include mysA, mysB, and mysC responsible for producing mycosporine-glycine (MG) from sedoheptulose 7-phosphate (S7P). The two strains utilize different enzymes, D-Ala-D-Ala ligase homologue (MysD) in N. punctiforme and NRPS-like enzyme (MysE) in A. variabilis, for amino acid conjugation to MG. MysE specifically generated shinorine, a serine conjugate of MG, while MysD exhibited substrate promiscuity, yielding both shinorine and a small amount of porphyra-334, a threonine conjugate of MG. We enhanced MAAs production by selecting mysA, mysB, and mysC from A. variabilis and mysD from N. punctiforme based on their activities. We further improved production by strengthening promoters, increasing gene copies, and introducing the xylose utilization pathway. Co-utilization of xylose with glucose or glycerol increased MAAs production by boosting the S7P pool through the pentose phosphate pathway. Overexpressing GND1 and ZWF1, key genes in the pentose phosphate pathway, further enhanced MAAs production. The highest achieved MAAs level was 249.0 mg/L (207.4 mg/L shinorine and 41.6 mg/L of porphyra-334) in YP medium containing 10 g/L glucose and 10 g/L xylose.ConclusionsY. lipolytica was successfully engineered to produce MAAs, primarily shinorine. This achievement involved the introduction of MAA biosynthetic genes from cyanobacteria, establishing xylose utilizing pathway, and overexpressing the pentose phosphate pathway genes. These results highlight the potential of Y. lipolytica as a promising yeast chassis strain for MAAs production, notably attributed to its proficient expression of MysE enzyme, which remains non-functional in S. cerevisiae, and versatile utilization of carbon sources like glycerol.
| S-EPMC10614408 | biostudies-literature
Project description:Sunscreens play a vital role in protecting human skin from photodamage upon UV exposure, but their effectiveness is limited by degradation and phototoxicity. Photoactivation of UV filters in sunscreen can generate reactive oxygen species, with accompanying cytotoxicity. Herein, we report stable, safe, fluorescent, and long-lasting sunscreens produced by microencapsulation of organic UV filters octylmethoxycinnamate (OMC) and butyl-methoxydibenzoylmethane (BMDM), alone and together, into a microporous zeolitic imidazole framework (ZIF-8). The visibly transparent OMC + BMDM@ZIF-8 sunscreens displayed complete broad-spectrum photoprotection against UV light even after 24 hours. Photostability testing of the sunscreens demonstrated the photo-protective nature of microporous ZIF-8 for stabilizing these UV filters. The sun protection factor (SPF) values for lotions containing 10% (w/w) OMC@ZIF-8, BMDM@ZIF-8 and OMC + BMDM@ZIF-8 sunscreens decreased from 29.8 to 26.0, 32.5 to 26.4, and 62.1 to 53.0, respectively, upon 24 hours of intense UV exposure. No release of the UV filters from the encapsulated formulations was observed. The ZIF-8 particles are too large to be transported across the stratum corneum. Thus, our findings suggest that zeolitic framework-encapsulated sunscreens could provide prolonged UV-protection efficacy and ultra-high SPF with reduced potential for degradation, phototoxicity, and transport across the skin.
| S-EPMC9056713 | biostudies-literature
Project description:An Arabidopsis thaliana line that is mutant for the R2R3 MYB gene, AtMYB4, shows enhanced levels of sinapate esters in its leaves. The mutant line is more tolerant of UV-B irradiation than wild type. The increase in sinapate ester accumulation in the mutant is associated with an enhanced expression of the gene encoding cinnamate 4-hydroxylase, which appears to be the principal target of AtMYB4 and an effective rate limiting step in the synthesis of sinapate ester sunscreens. AtMYB4 expression is downregulated by exposure to UV-B light, indicating that derepression is an important mechanism for acclimation to UV-B in A.thaliana. The response of target genes to AtMYB4 repression is dose dependent, a feature that operates under physiological conditions to reinforce the silencing effect of AtMYB4 at high activity. AtMYB4 works as a repressor of target gene expression and includes a repression domain. It belongs to a novel group of plant R2R3 MYB proteins involved in transcriptional silencing. The balance between MYB activators and repressors on common target promoters may provide extra flexibility in transcriptional control.
| S-EPMC305818 | biostudies-literature