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The pathways for biosynthesis of glycogen inbacteria and starch in plants are evolutionarily andbiochemically related. They are regulated primarily by ADP?glucose pyrophosphorylase, which evolved to satisfy metabolic requirements of a particular organism. Despite the importance of these two pathways, little is known about the mechanism that controls pyrophosphorylase activity or the location of its allosteric sites. Here, we report pyruvate-bound crystal structures of ADP-glucose pyrophosphorylase from the bacterium Agrobacterium tumefaciens, identifying a previously elusive activator site for the enzyme. We found that the tetrameric enzyme binds two molecules of pyruvate in a planar conformation. Each binding site is located in a crevice between the C-terminal domains of two subunits where they stack via a distinct β-helix region. Pyruvate interacts with the side chain of Lys-43 and with the peptide backbone of Ser-328 and Gly-329 from both subunits. These structural insights led to the design of two variants with altered regulator properties. In one variant (K43A), the allosteric effect was absent, whereas in the other (G329D), the introduced Asp mimicked the presence of pyruvate. The latter generated an enzyme that was pre-activated and insensitive to further activation by pyruvate. Our study furnishes a deeper understanding of how glycogen biosynthesis is regulated in bacteria and the mechanism by which transgenic plants increased their starch production. These insights will facilitate rational approaches to enzyme engineering for starch production in crops of agricultural interest and will promote further study of allosteric signal transmission and molecular evolution in this important enzyme family. Fil: Hill, B. L.. Dpt Of Chem And Biochemistry. Loyola University Chicago; Estados Unidos Fil: Mascarenhas, R.. Dpt Of Chem And Biochemistry. Loyola University Chicago; Estados Unidos Fil: Patel, H. P.. Dpt Of Chem And Biochemistry. Loyola University Chicago; Estados Unidos Fil: Asención Diez, Matías Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Wu, R.. Dpt Of Chem And Biochemistry. Loyola University Chicago; Estados Unidos Fil: Iglesias, Alberto Alvaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Liu, D.. Dpt Of Chem And Biochemistry. Loyola University Chicago; Estados Unidos Fil: Ballicora, M. A.. Dpt Of Chem And Biochemistry. Loyola University Chicago; Estados Unidos

The traditional view of starch metabolism has focused on the multiplicity of enzymes and enzyme isoforms contributing to the production of the constituent polymers, amylopectin and amylose. However, knowledge of these enzymes has not provided a full insight into many aspects of starch biosynthesis. This enzyme-centered view has recently been augmented by the discovery and characterization of novel proteins with proposed regulatory, scaffolding, and interactive roles. This begins to reveal an unprecedented level of complexity beyond mere glucan biosynthesis, enabling us to envisage how starch granules are initiated and grow into specific forms, allowing it to serve biological roles beyond just carbohydrate storage. This review focuses on very recent findings in this vibrant field, highlighting the evolutionary novelty.

A series of UDP-D-glucose derivatives and precursors that have been modified at C-3 were synthesised from D-glucose as potential chain terminators of beta-glucan biosynthesis. None of the UDP-derivatives or the precursors tested displayed significant anti-fungal activity in a series of germination assays on the dermatophyte Trichophyton rubrum.

ADPGlucose pyrophosphorylase (ADPG PPase) catalyzes a key step in glucan biosynthesis. Structure-function studies of the enzyme will facilitate the engineering of a more active enzyme to increase b...

The publisher regrets that in the above-mentioned article the title and authors were printed wrong. The correct version is reprinted here. “The role of the Candida albicans histidine kinase ( CHK1 ) gene in the regulation of cell wall mannan …

ADP-glucose pyrophosphorylase (ADPG PPase) is the rate limiting enzyme in the glucan biosynthesis pathway, a vital source for renewable and biodegradable carbon. Thus ADPG PPase is an attractive ta...

Three hyphal malformation inducers were isolated from fungi and their structures identified at (+)-isoepoxydon (1), brefeldin A (2) and ophiobolin A (4), respectively. Two of them, 1 and 4, were shown to be β-1,3-glucan synthetase inhibitors.

Bisvertinolone (1) that previously isolated as a fungal yellow metabolite was re-isolated from Acremonium strictum as a hyphal malformation inducer in fungi. Bisvertinolone was found to be the first β-1,6-glucan biosynthesis inhibitor, and its absolute stereochemistry determined by spectroscopic analysis.

A survey of the literature concerning β -glucan biosynthesis in yeast indicates the existence of a low number of reports in this field. For this reason, we will emphasize not only the few findings concerning both the biochemical properties of glucan-synthetase and the chemical nature of the synthesized product, but also the contradictions published on this topic.

GDP- and UDP-deoxyglucose inhibit the incorporation of glucose from UDP-glucose into dolichyl phosphate glucose and dolichyl pyrophosphate oligosaccharides. GDP-deoxyglucose inhibits by competing with the physiological nucleotide sugars for dolichyl phosphate, and dolichyl phosphate deoxyglucose is formed. This inhibition is reversed by excess of dolichyl phosphate. UDP-deoxyglucose does not give rise to a lipid-linked derivative, and inhibition by this analog is not reversed by dolichyl phosphate. The UDP- and GDP-derivatives of deoxyglucose inhibit the incorporation of glucose into glucose-containing glycoproteins. This effect seems to be the result of the inhibition of lipid intermediates glucosylation and is comparable to the effect produced by coumarin. Cellulose synthetase activity is not affected by UDP- or GDP-deoxyglucose. On the other hand, deoxyglucose inhibits the formation of beta-1,4-glucans in vivo.

Incubation of UDP-[14C]Glc with the inner membranes of Agrobacterium tumefaciens leads to the formation of cyclic beta 1-2 glucan and trichloroacetic acid-insoluble compounds. The proteolysis products of the latter show a positive charge in acid and a negative charge in alkaline buffers. The cyclic beta 1-2 glucan and the trichloroacetic acid insoluble compounds yield the same products on partial acid hydrolysis. Addition of excess non-radioactive UDP-Glc to the reaction mixture nearly stops the formation of radioactive beta 1-2 glucan and leads to a rapid fall of radioactivity in the trichloroacetic acid precipitate. Alkaline treatment of the insoluble compounds under conditions of beta-elimination leads to the partial release of free saccharides (about 30%). It is concluded that beta 1-2 glucan chains are built up joined to a protein and then released as free cyclic beta 1-2 glucan. original Fil: Zorreguieta, Ángeles. Instituto de Investigaciones Bioquímicas Fundación Campomar ; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Ugalde, Rodolfo A.. Instituto de Investigaciones Bioquímicas Fundación Campomar ; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Leloir, Luis Federico. Instituto de Investigaciones Bioquímicas Fundación Campomar ; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina Escala de grises 6 páginas en pdf LFL-PI-O-ART. Artículos científicos Unidad documental simple AR-HYL-2018

We attempted to epimerize 1-deoxynojirimycin to produce 1-deoxymannojirimycin, a potent mannosidase inhibitor which blocks conversion of high-mannose to complex saccharide on N-asparagine linked glucan biosynthesis. The data reported describes the microbial conversion of 1-deoxynojirimycin to the manno-form and its glycosidase inhibitory activity