title: Shuttling of (deoxy-) purine nucleotides between compartments of the diatom Phaeodactylum tricornutum.
abstract: Diatom plastids show several peculiarities when compared with primary plastids of higher plants or algae. They are surrounded by four membranes and depend on nucleotide uptake because, unlike in plants, nucleotide de novo synthesis exclusively occurs in the cytosol. Previous analyses suggest that two specifically adapted nucleotide transporters (NTTs) facilitate the required passage of nucleotides across the innermost plastid membrane. However, nucleotide transport across the additional plastid membranes remains to be clarified. Phylogenetic studies, transport assays with the recombinant protein as well as GFP-based targeting analyses allowed detailed characterization of a novel isoform (PtNTT5) of the six NTTs of Phaeodactylum tricornutum. PtNTT5 exhibits low amino acid similarities and is only distantly related to all previously characterized NTTs. However, in a heterologous expression system, it acts as a nucleotide antiporter and prefers various (deoxy-) purine nucleotides as substrates. Interestingly, PtNTT5 is probably located in the endoplasmic reticulum, which in diatoms also represents the outermost plastid membrane. PtNTT5, with its unusual transport properties, phylogeny and localization, can be taken as further evidence for the establishment of a sophisticated and specifically adapted nucleotide transport system in diatom plastids.
authors: Pflanzliche Ökophysiologie, Fachbereich Biologie, Universität Konstanz, 78457, Konstanz, Germany.
authors: Lili
authors: L
authors: Chu
authors: Pflanzliche Ökophysiologie, Fachbereich Biologie, Universität Konstanz, 78457, Konstanz, Germany.
authors: Ansgar
authors: A
authors: Gruber
authors: Pflanzenphysiologie, Technische Universität Kaiserslautern, 67653, Kaiserslautern, Germany.
authors: Michelle
authors: M
authors: Ast
authors: Department of Animal Science, Iowa State University, Ames, IA, 50011, USA.
authors: Stephan
authors: S
authors: Schmitz-Esser
authors: Pflanzenphysiologie, Technische Universität Kaiserslautern, 67653, Kaiserslautern, Germany.
authors: Jacqueline
authors: J
authors: Altensell
authors: Pflanzenphysiologie, Technische Universität Kaiserslautern, 67653, Kaiserslautern, Germany.
authors: Horst Ekkehard
authors: HE
authors: Neuhaus
authors: Pflanzliche Ökophysiologie, Fachbereich Biologie, Universität Konstanz, 78457, Konstanz, Germany.
authors: Peter G
authors: PG
authors: Kroth
authors: Pflanzenphysiologie, Technische Universität Kaiserslautern, 67653, Kaiserslautern, Germany.
authors: Ilka
authors: I
authors: Haferkamp
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D017920:Antiporters / Q000378:metabolism; D001692:Biological Transport; D017377:Diatoms / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D010802:Phylogeny; D011685:Purine Nucleotides / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: D017920:Antiporters; D026901:Membrane Transport Proteins; D011685:Purine Nucleotides; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate
keywords: complex plastid; diatom; endoplasmic reticulum (ER); energy; nucleotide synthesis; nucleotide transport