Mycosporine-like amino acid

Mycosporine-like amino acids (MAAs) are small secondary metabolites produced by organisms that live in environments with high volumes of sunlight, usually marine environments. So far there are up to 20 known MAAs identified. They are commonly described as “microbial sunscreen” but their function is not limited to sun protection.

MAAs are widespread in the microbial world and have been reported in many microorganisms including heterotrophic bacteria,cyanobacteria,microalgae,macroalgae, ascomycetous and basidiomycetousfungi, as well as some multi-cellular organisms. Most research done on MAAs is on their light absorbing and radiation protecting properties. The first thorough description of MAAs was done in cyanobacteria living in a high UV radiation environment. The major unifying characteristic among all MAAs is light absorption. All MAAs absorb UV light that can be destructive to biological molecules (DNA, Proteins, etc.). Though most MAA research is done on their photo-protective capabilities, they are also multifunctional secondary metabolites that have many cellular functions. MAAs are effective antioxidant molecules and are able to stabilize free radicals within their ring structure. In addition to protecting cells from mutation via UV radiation and free radicals, MAAs are able to boost cellular tolerance to desiccation, salt stress, and heat stress.

Mycosporine–like amino acids are rather small molecules (<400Da). The structures of over 30 Mycosporine-like amino acids have been resolved and all contain a central cyclohexenone or cyclohexenimine ring and a wide variety of substitutions. The ring structure is thought to absorb UV light and accommodate free radicals. All MAAs absorb ultraviolet light, typically between 310 and 340 nm. It is this light absorbing property that allows MAAs to protect cells from harmful UV radiation. Biosynthetic pathways of specific MAAs depend on the specific MAA and the organism that is producing it. These biosynthetic pathways often share common enzymes and intermediates with other major biosynthetic pathways. An example of this is the shikimate pathway that is classically used to create phenylalanine; many intermediates and enzymes from this pathway are utilized in MAA synthesis.

...
Wikipedia