Chemical analysis of stalk components of Dictyostelium discoideum

Freeze, Hud; Loomis, William F.

doi:10.1016/0304-4165(78)90086-7

Cited by 32 publications

(11 citation statements)

References 11 publications

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“…The stalk composition is similar to that of the surface sheath: approximately 50% cellulose, 15% protein and 35% polysaccharides and fatty acids [56]. Cells within the stalk tube, the stalk cell s (DDANAT:0000413), are around 8 microns in diameter, polyhedric, highly vacuolated, and are surrounded by a cell wall composed of cellulose.…”

Section: Resultsmentioning

confidence: 99%

An anatomy ontology to represent biological knowledge in Dictyostelium discoideum

et al. 2008

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Section: Resultsmentioning

confidence: 99%

An anatomy ontology to represent biological knowledge in Dictyostelium discoideum

et al. 2008

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“…Blanton and D.H. Northcote: Dictyostelium 1,4-fl-D-glucan synthase lulose). Other reports of partial and enzymatic hydrolysis of D. discoideum stalks have given no indication of the presence of 1,3-fl-linked glucan polymers (Raper and Fennell 1952;Freeze and Loomis 1978).…”

Section: Discussionmentioning

confidence: 95%

“…Only when aggregates become consolidated and begin to develop an organizing tip is cellulose made. Cellulose microfibrils are found in the slime sheath that surrounds consolidated and tipped aggregates, pseudoplasmodia, and sorocarps (Raper and Fennell 1952;Hohl and Jehli 1973;Freeze and Loomis 1977), in the stalk tube and stalk cell walls (Raper and Fennell 1952;Mfihlethaler 1956;Gezelius and R~mby 1957;George and Hohl 1969;Freeze and Loomis 1978), and in the spore walls (Mfihlethaler 1956;Hemmes et al 1972). Because D. discoideum exhibits induced cellulose synthesis and is easily manipulated experimentally, it is a good model organism for the study of eukaryotic cellulose synthesis (Delmer 1983).…”

Section: Introductionmentioning

confidence: 99%

A 1,4-?-D-glucan-synthase system from Dictyostelium discoideum

Blanton

Northcote

1990

Planta

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Particulate membrane preparations have been isolated from culminating Dictyostelium discoideum cells. The preparations incorporated glucose from uridine 5'-diphosphate-glucose into a glucose polymer or polymers. These have been shown to be homopolymers of β-linked glucose. A high percentage (78% by methylation analysis) of the linkages formed are 1,4-linkages and a lower percentage (12%) are 1,3-linkages. The glucan-synthase complex present in the particulate membrane preparation has an apparent Km of 0.28 mM and a Vmax of 1.59 nmol·min(-1)·(mg protein)(-1). The enzyme system is dependent upon Mg(2+) and cellobiose for maximal activity, but is inhibited by millimolar levels of Ca(2+). Particulate membrane preparations were made from cells at various times during a synchronous developmental time course and demonstrated that the glucan-synthase activity appeared at the tight-aggregate stage of development.

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“…During the formation of the slug and fruiting body, proteins and cellulose are deposited as an extracellular matrix, providing the organism with environmental protection and structural rigidity (1)(2)(3)(4). Cellulose is also found in the sheath that surrounds the cell aggregates and is deposited in the stalk, stalk cell walls, and spore coats (2,5). Thus, the deposition and reorganization of cellulose upon morphogenesis into the fruiting body are crucial to the development and propagation of the organism.…”

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confidence: 99%

Biochemical and Structural Characterizations of Two Dictyostelium Cellobiohydrolases from the Amoebozoa Kingdom Reveal a High Level of Conservation between Distant Phylogenetic Trees of Life

Hobdey

Knott

Momeni

et al. 2016

Appl Environ Microbiol

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Glycoside hydrolase family 7 (GH7) cellobiohydrolases (CBHs) are enzymes commonly employed in plant cell wall degradation across eukaryotic kingdoms of life, as they provide significant hydrolytic potential in cellulose turnover. To date, many fungal GH7 CBHs have been examined, yet many questions regarding structure-activity relationships in these important natural and commercial enzymes remain. Here, we present the crystal structures and a biochemical analysis of two GH7 CBHs from social amoeba: Dictyostelium discoideum Cel7A (DdiCel7A) and Dictyostelium purpureum Cel7A (DpuCel7A). DdiCel7A and DpuCel7A natively consist of a catalytic domain and do not exhibit a carbohydrate-binding module (CBM). The structures of DdiCel7A and DpuCel7A, resolved to 2.1 Å and 2.7 Å, respectively, are homologous to those of other GH7 CBHs with an enclosed active-site tunnel. Two primary differences between the Dictyostelium CBHs and the archetypal model GH7 CBH, Trichoderma reesei Cel7A (TreCel7A), occur near the hydrolytic active site and the product-binding sites. To compare the activities of these enzymes with the activity of TreCel7A, the family 1 TreCel7A CBM and linker were added to the C terminus of each of the Dictyostelium enzymes, creating DdiCel7A CBM and DpuCel7A CBM , which were recombinantly expressed in T. reesei. DdiCel7A CBM and DpuCel7A CBM hydrolyzed Avicel, pretreated corn stover, and phosphoric acid-swollen cellulose as efficiently as TreCel7A when hydrolysis was compared at their temperature optima. The K i of cellobiose was significantly higher for DdiCel7A CBM and DpuCel7A CBM than for TreCel7A: 205, 130, and 29 M, respectively. Taken together, the present study highlights the remarkable degree of conservation of the activity of these key natural and industrial enzymes across quite distant phylogenetic trees of life. IMPORTANCE GH7CBHs are among the most important cellulolytic enzymes both in nature and for emerging industrial applications for cellulose breakdown. Understanding the diversity of these key industrial enzymes is critical to engineering them for higher levels of activity and greater stability. The present work demonstrates that two GH7 CBHs from social amoeba are surprisingly quite similar in structure and activity to the canonical GH7 CBH from the model biomass-degrading fungus T. reesei when tested under equivalent conditions (with added CBM-linker domains) on an industrially relevant substrate. Dictyostelia are a class of social amoebae (historically known as slime molds) containing four different groups of terrestrial bacterivores from the kingdom Amoebozoa. During vegetative growth, dictyostelia exist as single-celled organisms; upon starvation, a lack of nutrients becomes preventive for vegetative growth and the cells aggregate into a multicellular slug. Slugs have a defined posterior and anterior, have the ability to migrate, are sensitive to light and temperature, and exhibit an innate immune system. When conditions are sufficiently severe, the slug can form a fruiting body, w...

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Chemical analysis of stalk components of Dictyostelium discoideum

Cited by 32 publications

References 11 publications

An anatomy ontology to represent biological knowledge in Dictyostelium discoideum

An anatomy ontology to represent biological knowledge in Dictyostelium discoideum

A 1,4-?-D-glucan-synthase system from Dictyostelium discoideum

Biochemical and Structural Characterizations of Two Dictyostelium Cellobiohydrolases from the Amoebozoa Kingdom Reveal a High Level of Conservation between Distant Phylogenetic Trees of Life

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