Isolation, Purification, Characterization of Cellulolytic Enzymes Produced by the Isolate Streptomyces omiyaensis
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Isolation
Cytoplasmic streaming
Physarum
Amoeba proteus
Plasmodium (life cycle)
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Thiotetromycin is isolated from Streptomyces sp. OM-674 discovered in the course of the screening for antibacterial antibiotics. The antibiotic was found to be a specific inhibitor of type II fatty acid synthase. In order to search acyl-CoA synthetase inhibitors, a kind of yeast, Candida lipolytica, was utilized as test organism for the primary screening. Four structurally related compounds named triacsin were isolated from Streptomyces sp. SK-1894 as a specific inhibitor of acyl-CoA synthetase I of C. lipolytica. Further biochemical studies revealed that triacsins inhibit acyl-CoA synthetases from widely different sources. The inhibition is competitive with respect to long chain fatty acids. The common N-hydroxytriazene moiety of triacsins is essential for inhibition. To discover inhibitors of mevalonate biosynthesis, Vero cells were used as test organism for the screening. A beta-lactone 1233A(F-244) isolated from Scopulariopsis sp. F-244 was demonstrated to inhibit mevalonate biosynthesis with assays using cell and enzyme systems. Further studies demonstrated that the compound inhibits 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase specifically and irreversibly. The geometry of the (2R, 3R)-beta-lactone ring in the structure is essential for specific inhibition against the enzyme.
Fatty acid synthesis
Acyl carrier protein
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Isolation
Proteolytic enzymes
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Infectivity
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Streptomycetaceae
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A selective inactivating enzyme for cytosolic aspartate aminotransferase (GOT) was found in the culture filtrate of Streptomyces violaceochromogenes No. 401, newly isolated from soil. The enzyme was purified and crystallized. The enzymespecifically inactivates cytosolic GOT but shows no activity on the mitochondrial isozyme. The enzymeproved to be a serine proteinase. Limited proteolysis of native GOTby the enzyme results in a loss of enzymatic activity.
Proteolysis
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ABSTRACT A virus infecting the haptophyte Phaeocystis pouchetii (Hariot) Lagerheim was isolated from Norwegian coastal waters in May 1995 at the end of a bloom of this phytoplankter. The virus was specific for P. pouchetii because it did not lyse 10 strains of P. globosa Scherffel, Phaeocystis sp., and P. antarctica Karsten. It was a double‐stranded DNA virus, and the viral particle was a polyhedron with a diameter of 130–160 nm. The virus had a main polypeptide of about 59 kDa and at least five minor polypeptides between 30 and 50 kDa. The latent period of the virus when propagated in cultures of P. pouchetii was 12–18 h, and the time required for complete lysis of the cultures was about 48 h. The burst size was estimated to be 350–600 viral particles per lysed cell.
Haptophyte
Virus isolation
Isolation
Virus-like particle
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A beta-1,6-glucanase was purified to apparent homogeneity from a commercial yeast digestive enzyme prepared from Streptomyces rochei by a series of column chromatographies. The molecular mass of the purified enzyme was 60 kDa by SDS-PAGE. The purified enzyme had an optimum pH range from 4.0 to 6.0 and was stable in the same pH range. The enzyme was stable under 50 degrees C but lost almost all activity at 60 degrees C. The enzyme was specific to beta-1,6-glucan and had little activity towards beta-1,3-glucan and beta-1,4-glucan. When the beta-1,6-glucan was hydrolyzed with the purified enzyme for 5 h, the reaction products contained 20% glucose, 36% gentiobiose, and 44% other oligosaccharides, suggesting that the enzyme is an endo-type glucanase. When the purified enzyme was used for the digestion of the cell wall of Saccharomyces cerevisiae, cell-wall proteins covalently bound to the cell-wall glucan were recovered as soluble forms, suggesting that this enzyme is useful for analysis of yeast-cell wall proteins.
Glucanase
Molecular mass
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Though synthesized with a cleavable signal peptide and devoid of membrane anchors, the 262-amino-acid-residue Streptomyces K15 DD-transpeptidase/penicillin-binding protein is membrane-bound. Overexpression in Streptomyces lividans resulted in the export of an appreciable amount of the synthesized protein (4 mg/litre of culture supernatant). The water-soluble enzyme was purified close to protein homogeneity with a yield of 75%. It requires the presence of 0.5 M-NaCl to remain soluble. It is indistinguishable from the detergent-extract wild-type enzyme with respect to molecular mass, thermostability, transpeptidase activity and penicillin-binding capacity.
Thermostability
Residue (chemistry)
Molecular mass
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Abstract The bacteria Streptomyces davawensis and Streptomyces cinnabarinus produce roseoflavin, the only known natural riboflavin (vitamin B 2 ) analogue with antibiotic activity. Roseoflavin can be considered a natural antimetabolite and has been postulated to be biosynthesized from riboflavin via the key intermediate 8‐demethyl‐8‐aminoriboflavin (AF). The required site‐specific substitution of one of the methyl groups on the dimethylbenzene ring of riboflavin by an amino group (to give AF) is challenging. The pathway from riboflavin to AF has remained elusive, and the corresponding enzyme/s was/were unknown. Herein, we show by systematic gene deletion, heterologous gene expression, and biochemical studies that the enzyme specified by the gene BN159_7989 from S. davawensis is able to carry out a whole set of chemical reactions starting from riboflavin‐5′‐phosphate to give the final product 8‐demethyl‐8‐aminoriboflavin‐5′‐phosphate (AFP).
Heterologous expression
Heterologous
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