Action of glycosidases on the saccharide moiety of the glucose—containing dolichyl diphosphate oligosaccharide

originalFil: Ugalde, Rodolfo Augusto. Instituto de Investigaciones Bioquímicas Fundación Campomar; ArgentinaFil: Staneloni, Roberto Julio. Instituto de Investigaciones Bioquímicas Fundación Campomar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Leloir, Luis Federico. Instituto de Investigaciones Bioquímicas Fundación Campomar; Argentinablanco y negro1 ejemplarLFL-PI-O-ART. Artículos científicosUnidad documental simpleAR-HYL-201

The biosynthetic pathway of asparagine-linked oligosaccharides of glycoproteins

A dolichyl diphosphate oligosaccharide containing glucose, mannose and N-acetylglucosamine is the precursor of the sugar -moiety of some glycoproteins. Studies of glycoproteins produced by virus-infected cells, using endo-N-acetylglycosaminidase for the liberation of the sugar moiety, have shown that the glucose-containing oligosaccharide is transferred to protein, then the glucose and some mannose residues are removed and acetlyglucosamine, galactose and sialic acid are added.originalFil: Staneloni, Roberto J.. Instituto de Investigaciones Bioquímicas Fundación Campomar; ArgentinaFil: Leloir, Luis Federico. Instituto de Investigaciones Bioquímicas Fundación Campomar; ArgentinaEscala de grises3 páginas en pdfLFL-PI-O-ART. Artículos científicosUnidad documental simpleAR-HYL-201

Transfer of Oligosaccharide to Protein from a Lipid Intermediate in Plants

A lipid-bound oligosaccharide was isolated from pea (Pisum sativum) cotyledons incubated with [(14)C]mannose. The oligosaccharide moiety appeared to be identical with the one obtained from rat liver, known to contain three glucoses, nine mannoses, and two N-acetylglucosamines, and to be involved in protein glycosylation. Enzymes obtained from soya (Glycine max) roots and developing pea cotyledons were found to catalyze the transfer of oligosaccharide from the lipid intermediate to endogenous protein. The enzymes require Mn(2+) and detergent for activity. Evidence is presented indicating that the lipid-bound oligosaccharide with three glucoses is transferred faster than that with less. Some of the peripheral mannoses could be removed without affecting the rate of transfer. The protein-bound oligosaccharide, formed by incubation of whole cotyledons or by transfer with the enzyme preparation, could be released by protease and endo-β-N-acetylglucosaminidase treatment, as expected for an asparagine-bound high mannose oligosaccharide

Formation of Lipid-Bound Oligosaccharides Containing Mannose. Their Role in Glycoprotein Synthesis

Incubation of GDP-[(14)C]mannose with liver microsomes and magnesium ions led to the formation of dolichol monophosphate mannose and of other acidlabile compounds that contain oligosaccharides. Formation of these compounds was enhanced by addition of an acceptor lipid in the same fractions of DEAE-cellulose chromatography where bound dolichol is found. Alkaline treatment of the oligosaccharides, obtained by acid methanolysis, followed by paper electrophoresis, gave rise to the formation of two positively charged substances believed to be formed by deacetylation of hexosamine residues. Incubation of the oligosaccharide-containing compounds with liver microsomes and manganese ions resulted in a transfer to endogenous protein. The role of dolichol derivatives in glycoprotein synthesis is discussed

A Constitutive Shade-Avoidance Mutant Implicates TIR-NBS-LRR Proteins in Arabidopsis Photomorphogenic Development

In plants, light signals caused by the presence of neighbors accelerate stem growth and flowering and induce a more erect position of the leaves, a developmental strategy known as shade-avoidance syndrome. In addition, mutations in the photoreceptors that mediate shade-avoidance responses enhance disease susceptibility in Arabidopsis thaliana. Here, we describe the Arabidopsis constitutive shade-avoidance1 (csa1) mutant, which shows a shade-avoidance phenotype in the absence of shade and enhanced growth of a bacterial pathogen. The csa1 mutant has a T-DNA inserted within the second exon of a Toll/Interleukin1 receptor–nucleotide binding site–leucine-rich repeat (TIR-NBS-LRR) gene, which leads to the production of a truncated mRNA. Arabidopsis plants transformed with the truncated TIR-NBS-LRR gene recapitulate the mutant phenotype, indicating that csa1 is a dominant-negative mutation that interferes with phytochrome signaling. TIR-NBS-LRR proteins have been implicated in defense responses in plants. RPS4, the closest homolog of CSA1, confers resistance to Pseudomonas syringae and complements the csa1 mutant phenotype, indicating that responses to pathogens and neighbors share core-signaling components in Arabidopsis. In Drosophila melanogaster and Caenorhabditis elegans, TIR domain proteins are implicated in both development and immunity. Thus, the dual role of the TIR domain is conserved across kingdoms