title: Identification and upregulation of biosynthetic genes required for accumulation of Mycosporine-2-glycine under salt stress conditions in the halotolerant cyanobacterium Aphanothece halophytica.
abstract: Mycosporine-like amino acids (MAAs) are valuable molecules that are the basis for important photoprotective constituents. Here we report molecular analysis of mycosporine-like amino acid biosynthetic genes from the halotolerant cyanobacterium Aphanothece halophytica, which can survive at high salinity and alkaline pH. This extremophile was found to have a unique MAA core (4-deoxygadusol)-synthesizing gene separated from three other genes. In vivo analysis showed accumulation of the mycosporine-2-glycine but not shinorine or mycosporine-glycine. Mycosporine-2-glycine accumulation was stimulated more under the stress condition of high salinity than UV-B radiation. The Aphanothece MAA biosynthetic genes also manifested a strong transcript level response to salt stress. Furthermore, the transformed Escherichia coli and Synechococcus strains expressing four putative Aphanothece MAA genes under the control of a native promoter were found to be capable of synthesizing mycosporine-2-glycine. The accumulation level of mycosporine-2-glycine was again higher under the high-salinity condition. In the transformed E. coli cells, its level was approximately 85.2 ± 0.7 μmol/g (dry weight). Successful production of a large amount of mycosporine in these cells provides a new opportunity in the search for an alternative natural sunscreen compound source.
authors.affiliation: Research Institute of Meijo University, Nagoya, Japan.
authors.forename: Rungaroon
authors.initials: R
authors.lastname: Waditee-Sirisattha
authors.forename: Hakuto
authors.initials: H
authors.lastname: Kageyama
authors.forename: Warangkana
authors.initials: W
authors.lastname: Sopun
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Teruhiro
authors.initials: T
authors.lastname: Takabe
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics*; D000458:Cyanobacteria / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects; D003511:Cyclohexanols; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D020869:Gene Expression Profiling; D005998:Glycine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D011401:Promoter Regions, Genetic; D012492:Salts / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D014466:Ultraviolet Rays; D015854:Up-Regulation
chemical_list: D003511:Cyclohexanols; D004269:DNA, Bacterial; D012492:Salts; C463482:mycosporine-2-glycine; D005998:Glycine