title: The nucleotide sugar transporters AtUTr1 and AtUTr3 are required for the incorporation of UDP-glucose into the endoplasmic reticulum, are essential for pollen development and are needed for embryo sac progress in Arabidopsis thaliana.
abstract: Uridine 5'-diphosphate (UDP)-glucose is transported into the lumen of the endoplasmic reticulum (ER), and the Arabidopsis nucleotide sugar transporter AtUTr1 has been proposed to play a role in this process; however, different lines of evidence suggest that another transporter(s) may also be involved. Here we show that AtUTr3 is involved in the transport of UDP-glucose and is located at the ER but also at the Golgi. Insertional mutants in AtUTr3 showed no obvious phenotype. Biochemical analysis in both AtUTr1 and AtUTr3 mutants indicates that uptake of UDP-glucose into the ER is mostly driven by these two transporters. Interestingly, the expression of AtUTr3 is induced by stimuli that trigger the unfolded protein response (UPR), a phenomenon also observed for AtUTr1, suggesting that both AtUTr1 and AtUTr3 are involved in supplying UDP-glucose into the ER lumen when misfolded proteins are accumulated. Disruption of both AtUTr1 and AtUTr3 causes lethality. Genetic analysis showed that the atutr1 atutr3 combination was not transmitted by pollen and was poorly transmitted by the ovules. Cell biology analysis indicates that knocking out both genes leads to abnormalities in both male and female germ line development. These results show that the nucleotide sugar transporters AtUTr1 and AtUTr3 are required for the incorporation of UDP-glucose into the ER, are essential for pollen development and are needed for embryo sac progress in Arabidopsis thaliana.
authors.affiliation: Plant Cell Biotechnology Millennium Nucleus, Center of Plant Biotechnology, Andres Bello University, República 217, Santiago, Chile.
authors.forename: Francisca
authors.initials: F
authors.lastname: Reyes
authors.forename: Gabriel
authors.initials: G
authors.lastname: León
authors.forename: Maribel
authors.initials: M
authors.lastname: Donoso
authors.forename: Federica
authors.initials: F
authors.lastname: Brandizzí
authors.forename: Andreas P M
authors.initials: AP
authors.lastname: Weber
authors.forename: Ariel
authors.initials: A
authors.lastname: Orellana
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005838:Genotype; D005947:Glucose / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009154:Mutation; D033704:Nucleotide Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000196:embryology / Q000378:metabolism* / Q000648:ultrastructure; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014530:Uridine Diphosphate / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; D033704:Nucleotide Transport Proteins; C466998:UTr1 protein, Arabidopsis; C551729:UTr3 protein, Arabidopsis; D014530:Uridine Diphosphate; D005947:Glucose