Phylogenetic analysis of genes involved in mycosporine-like amino acid biosynthesis in symbiotic dinoflagellates
- 682 Downloads
Mycosporine-like amino acids (MAAs) are multifunctional secondary metabolites involved in photoprotection in many marine organisms. As well as having broad ultraviolet (UV) absorption spectra (310–362 nm), these biological sunscreens are also involved in the prevention of oxidative stress. More than 20 different MAAs have been discovered so far, characterized by distinctive chemical structures and a broad ecological distribution. Additionally, UV-screening MAA metabolites have been investigated and used in biotechnology and cosmetics. The biosynthesis of MAAs has been suggested to occur via either the shikimate or pentose phosphate pathways. Despite their wide distribution in marine and freshwater species and also the commercial application in cosmetic products, there are still a number of uncertainties regarding the genetic, biochemical, and evolutionary origin of MAAs. Here, using a transcriptome-mining approach, we identify the gene counterparts from the shikimate or pentose phosphate pathway involved in MAA biosynthesis within the sequences of the reef-building coral symbiotic dinoflagellates (genus Symbiodinium). We also report the highly similar sequences of genes from the proposed MAA biosynthetic pathway involved in the metabolism of 4-deoxygadusol (direct MAA precursor) in various Symbiodinium strains confirming their algal origin and conserved nature. Finally, we reveal the separate identity of two O-methyltransferase genes, possibly involved in MAA biosynthesis, as well as nonribosomal peptide synthetase and adenosine triphosphate grasp homologs in symbiotic dinoflagellates. This study provides a biochemical and phylogenetic overview of the genes from the proposed MAA biosynthetic pathway with a focus on coral endosymbionts.
KeywordsUV MAAs Symbiodinium Zooxanthellae Coral–algal symbiosis Coral bleaching
Thanks to Olga Pantos, Alicia Lloyd and Iris Depaz for helpful comments about the manuscript. This work was supported by a University of Queensland Postdoctoral Fellowship for Women and a Discovery Early Career Researcher Award (DECRA) to NNR.
- Britton G (1995) Structure and properties of carotenoids in relation to function. FASEB J 9:1551–1558Google Scholar
- Felsenstein J (1989) PHYLIP—Phylogeny inference package (Version 3.2). Cladistics 5:164–166Google Scholar
- Shick JM, Romaine-Lioud S, Ferrier-Pagès C, Gattuso JP (1999) Ultraviolet-B radiation stimulates shikimate pathway-dependent accumulation of mycosporine-like amino acids in the coral Stylophora pistillata despite decreases in its population of symbiotic dinoflagellates. Limnol Oceanogr 44:1667–1682CrossRefGoogle Scholar
- Singh SP, Kumari S, Rastogi RP, Singh KL, Sinha RP (2008) Mycosporine-like amino acids (MAAs): chemical structure, biosynthesis and significance as UV-absorbing/screening compounds. Indian J Exp Biol 46:7–17Google Scholar
- Watanabe S, Sudo K, Nagashima T, Takemura T, Kawase H, Nozawa T (2011) Future projections of surface UV-B in a changing climate. J Geophys Res D: Atmos 116Google Scholar