title: Oxygen induces fatty acid (n-6)-desaturation independently of temperature in Acanthamoeba castellanii.
abstract: Induction of a microsomal oleate delta12 (n-6) desaturase which is mainly responsible for an increase in membrane lipid unsaturation at low temperature has been observed in the free-living amoeba Acanthamoeba castellanii. In this study we show that the enzyme can also be regulated by oxygen independently of temperature in batch cultures grown to O2-limitation. Raising the oxygen concentration from below the lower limit of detection (< 0.1 microM) to approximately air-saturation (230 microM), whilst maintaining the growth temperature constant (30 degrees C), increased lipid unsaturation and elevated n-6-desaturase activity 2.3-fold. Addition of the protein synthesis inhibitor, anisomycin, showed that increased desaturase activity was due to new protein synthesis rather than activation of pre-existing enzyme. These observations are important for future studies of the mechanism of temperature adaptation in poikilotherms.
authors.affiliation: Microbiology Group, School of Pure and Applied Biology, University of Wales Cardiff, UK.
authors.forename: K
authors.initials: K
authors.lastname: Thomas
authors.forename: A
authors.initials: A
authors.lastname: Rutter
authors.forename: M
authors.initials: M
authors.lastname: Suller
authors.forename: J
authors.initials: J
authors.lastname: Harwood
authors.forename: D
authors.initials: D
authors.lastname: Lloyd
mesh_terms: D000048:Acanthamoeba / Q000201:enzymology*; D000818:Animals; D004790:Enzyme Induction; D044943:Fatty Acid Desaturases / Q000096:biosynthesis*; D008861:Microsomes / Q000201:enzymology; D010100:Oxygen / Q000378:metabolism*; D013696:Temperature
chemical_list: D044943:Fatty Acid Desaturases; C040448:delta-12 fatty acid desaturase; D010100:Oxygen