title: Nitrate and amino acid availability affects glycine betaine and mycosporine-2-glycine in response to changes of salinity in a halotolerant cyanobacterium Aphanothece halophytica.
abstract: A halotolerant cyanobacterium Aphanothece halophytica thrives in extreme salinity with accumulation of a potent osmoprotectant glycine betaine. Recently, this cyanobacterium was shown to accumulate sunscreen molecule mycosporine-2-glycine significantly at high salinity. In this study, we investigated effects of nitrate and amino acid provision on the accumulation of glycine betaine and mycosporine-2-glycine. With elevated nitrate concentrations at high salinity, intracellular levels of both metabolites were enhanced. Six-fold high nitrate concentration increased the relative amounts of glycine betaine and mycosporine-2-glycine to be 1.5 and 2.0 folds compared with control condition : Increased levels were time- and dose-dependent manner. Exogenous supply of glycine/serine at high salinity resulted in the similar trends as observed in excess nitrate experiment. Intracellular level of glycine betaine increased ∼1.6 folds with glycine/serine supplementation. These supplementations also caused the increased level of mycosporine-2-glycine, namely 1.4 and 2 folds by glycine and serine, respectively. The transcription of glycine betaine and mycosporine-2-glycine biosynthetic genes was strongly induced under high-nitrate-salt condition. These results suggest the dependence of glycine betaine and mycosporine-2-glycine productions on substrate availability, and the effect of nitrate was possibly associated with stimulation of osmoprotectant increment in this extremophile.
authors.affiliation: Research Institute of Meijo University, Nagoya 468-8502, Japan Department of Microbiology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
authors.forename: Rungaroon
authors.initials: R
authors.lastname: Waditee-Sirisattha
authors.affiliation: Graduate School of Environmental and Human Sciences, Meijo University, Nagoya 468-8502, Japan.
authors.forename: Hakuto
authors.initials: H
authors.lastname: Kageyama
authors.affiliation: Faculty of Science & Technology Meijo University, Nagoya 468-8502, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Fukaya
authors.affiliation: National Research Center on Plant Biotechnology, IARI, New Delhi 110012, India.
authors.forename: Vandna
authors.initials: V
authors.lastname: Rai
authors.affiliation: Research Institute of Meijo University, Nagoya 468-8502, Japan Graduate School of Environmental and Human Sciences, Meijo University, Nagoya 468-8502, Japan takabe@meijo-u.ac.jp.
authors.forename: Teruhiro
authors.initials: T
authors.lastname: Takabe
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics; D001622:Betaine / Q000378:metabolism*; D000458:Cyanobacteria / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D003511:Cyclohexanols / Q000378:metabolism*; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D009566:Nitrates / Q000378:metabolism*; D054712:Salinity; D055049:Salt Tolerance; D012694:Serine / Q000737:chemistry / Q000494:pharmacology; D013312:Stress, Physiological / Q000235:genetics
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D003511:Cyclohexanols; D009566:Nitrates; C463482:mycosporine-2-glycine; D001622:Betaine; D012694:Serine; D005998:Glycine
keywords: amino acids; glycine betaine; halotolerant cyanobacterium; mycosporine-2-glycine; nitrate; salt stress