title: A predicted geranylgeranyl reductase reduces the ω-position isoprene of dolichol phosphate in the halophilic archaeon, Haloferax volcanii.
abstract: In N-glycosylation in both Eukarya and Archaea, N-linked oligosaccharides are assembled on dolichol phosphate prior to transfer of the glycan to the protein target. However, whereas only the α-position isoprene subunit is saturated in eukaryal dolichol phosphate, both the α- and ω-position isoprene subunits are reduced in the archaeal lipid. The agents responsible for dolichol phosphate saturation remain largely unknown. The present study sought to identify dolichol phosphate reductases in the halophilic archaeon, Haloferax volcanii. Homology-based searches recognize HVO_1799 as a geranylgeranyl reductase. Mass spectrometry revealed that cells deleted of HVO_1799 fail to fully reduce the isoprene chains of H. volcanii membrane phospholipids and glycolipids. Likewise, the absence of HVO_1799 led to a loss of saturation of the ω-position isoprene subunit of C(55) and C(60) dolichol phosphate, with the effect of HVO_1799 deletion being more pronounced with C(60) dolichol phosphate than with C(55) dolichol phosphate. Glycosylation of dolichol phosphate in the deletion strain occurred preferentially on that version of the lipid saturated at both the α- and ω-position isoprene subunits.
authors.affiliation: Department of Life Sciences, Ben Gurion University of the Negev, Beersheva 84105, Israel.
authors.forename: Shai
authors.initials: S
authors.lastname: Naparstek
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Guan
authors.forename: Jerry
authors.initials: J
authors.lastname: Eichler
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism*; D002070:Butadienes / Q000737:chemistry / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002853:Chromatography, Liquid; D004288:Dolichol Phosphates / Q000737:chemistry / Q000378:metabolism*; D017353:Gene Deletion; D006017:Glycolipids / Q000737:chemistry / Q000378:metabolism; D019622:Haloferax volcanii / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D045782:Hemiterpenes / Q000737:chemistry / Q000378:metabolism; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010420:Pentanes / Q000737:chemistry / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D019843:Archaeal Proteins; D002070:Butadienes; D004288:Dolichol Phosphates; D006017:Glycolipids; D045782:Hemiterpenes; D008563:Membrane Lipids; D010420:Pentanes; D010743:Phospholipids; C005059:isoprene; D010088:Oxidoreductases; C110920:geranylgeranyl reductase