title: Distribution of heterocyst glycolipids in cyanobacteria.
abstract: Thirty-four axenic strains of cyanobacteria were analysed for their glycolipid content using high performance liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (HPLC/ESI-MS(2)). Species of the families Nostocaceae and Rivulariaceae, capable of biosynthesising heterocysts, contained a suite of glycolipids consisting of sugar moieties glycosidically bound to long-chain diols, triols, keto-ols and keto-diols. The aglycone moiety consisted of C(26) or C(28) carbon-chains with hydroxyl groups at the C-3, omega-1 or omega-3 positions. Keto-ols and keto-diols contained their carbonyl functionalities likely at the C-3 position. These compounds were absent in all analysed unicellular and filamentous non-heterocystous cyanobacteria and in the heterocyst-forming cyanobacterium Anabaena CCY9922 grown in the presence of combined nitrogen, supporting the idea that the long-chain glycolipids are an important and unique structural component of the heterocyst cell envelope. The glycolipids 1-(O-hexose)-3,25-hexacosanediol and 1-(O-hexose)-3-keto-25-hexacosanol were ubiquitously distributed in species of the family Nostocaceae. 1-(O-hexose)-3,25,27-octacosanetriol and 1-(O-hexose)-3-keto-25,27-octacosanediol were dominant in members of the Calothrix genus, while traces of those compounds were detected only in one species of the Nostocaceae family. Their distribution in heterocystous cyanobacteria suggests a chemotaxonomic relevance that might allow distinguishing between species of different genera. Culture experiments indicate that the amount of keto-ols and keto-diols decreases relatively to their corresponding diols and triols counterparts with increasing temperature. Possibly, this is an adaptation to optimise the cell wall gas permeability, preventing inactivation of the oxygen-sensitive nitrogenase while allowing the highest diffusion of atmospheric dinitrogen into the heterocyst.
authors.affiliation: NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Organic Biogeochemistry, P.O. Box 59, 1790 AB Den Burg, The Netherlands. thorsten.bauersachs@nioz.nl
authors.forename: Thorsten
authors.initials: T
authors.lastname: Bauersachs
authors.forename: Justine
authors.initials: J
authors.lastname: Compaoré
authors.forename: Ellen C
authors.initials: EC
authors.lastname: Hopmans
authors.forename: Lucas J
authors.initials: LJ
authors.lastname: Stal
authors.forename: Stefan
authors.initials: S
authors.lastname: Schouten
authors.forename: Jaap S
authors.initials: JS
authors.lastname: Sinninghe Damsté
mesh_terms: D056226:Bacterial Structures; D002241:Carbohydrates / Q000737:chemistry; D002473:Cell Wall / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000737:chemistry*; D006017:Glycolipids / Q000032:analysis* / Q000737:chemistry; D015394:Molecular Structure; D009584:Nitrogen / Q000378:metabolism; D009591:Nitrogenase / Q000378:metabolism
chemical_list: D002241:Carbohydrates; D006017:Glycolipids; D009591:Nitrogenase; D009584:Nitrogen