Streptomyces avermitilis Avermectins

One of the most successful attempts at generating a wide range of analogs of a natural product resulted from the isolation of a mutant of the avermectin-producing organism, Streptomyces avermitilis. Avermectins types a and b derive their C-25 substituents from isoleucme and valine, via incorporation of these compounds as coenzyme A derivatives of isobutync and 2-methylbutyric acids, respectively. This mutant lacked the functional branched-chain 2-oxo acid dehydrogenase activity and could not therefore incorporate these likely... 

Ikeda, H., Nonomiya, T., Usami, M. et aL (1999) Organization of the biosynthetic gene cluster for the polyketide anthelmintic macrolide avermectin in Streptomyces avermitilis. Proceedings of the National Academy of Sciences of the United States of America, 96, 9509-9514. 

Hafner, E.W., Holley, B.W., Holdom, K.S. et al. (1991) Branched-chain fatty acid requirement for avermectin production by a mutant of Streptomyces avermitilis lacking branched-chain 2-oxo acid dehydrogenase activity. Journal of Antibiotics (Tokyo), 44, 349-356. 

Ikeda, H. and Omura, S. (1995) Control of avermectin biosynthesis in Streptomyces avermitilis for the selective production of a useful component. Journal of Antibiotics (Tokyo), 48, 549-562. 

The microorganism was classified as a new species of actinomycete. Streptomyces avermitilis. Its anthelmintic activity was shown to reside in 8 closely related macrocyclic lactones, named avermectins, which were also found to possess activity against free-living and parasitic arthropods. One of the natural components, avermectin is now being evaluated as a pesticide for the control of mites of citrus and cotton crops and control of the Red Imported Fire Ant. A chemical derivative, 22,23-dihydroavermectin or ivermectin, has been developed as an antiparasitic agent. It is being marketed for use in cattle, horses and sheep and is expected to become available for swine and dogs. 

Ivermectin, a semisynthetic macrocyclic lactone, is a mixture of avermectin Bia and Bib- is derived from the soil actinomycete Streptomyces avermitilis. 

CD Denoya, RW Fedechko, EW Hafner, HAI McArthur, MR Morgenstern, DD Skinner, K Stutzman-Engwall, RG Wax, WC Wemau. A second branched-chain OC-keto acid dehydrogenase gene cluster (bkdFGH) from Streptomyces avermitilis. its relationship to avermectin biosynthesis and the construction of a bkdF mutant suitable for the production of novel antiparasitic avermectins. J Bacteriol 177 3504-3511, 1995. 

Engineering Streptomyces avermitilis for the Production of Novel Avermectins Mutant Design and Titer Improvement... 

Eight naturally occurring, structurally related avermectins are produced by Streptomyces avermitilis [7], The avermectin polyketide structure is derived from seven acetate and five propionate residues, together with a single 2-methylbutyric acid or isobutyric acid residue which forms the sec-butyl or isopropyl group attached to the C25 of the spiroketal moiety [8,9] (Fig. 1). The avermectin agly-cone is further modified by glycosylation at C13, with the attachment of two O-methylated oleandrose residues and O-methylation at C5. Thus, S. avermitilis... 

MD Schulman, D Valentino, C Ruby. Avermectin B O-methyltransferase of Streptomyces avermitilis. Fed Proc 44 931, 1985. 

H Ikeda, LR Wang, T Ohta, J Inokoshi, S Omura. Cloning of the gene encoding avermectin B 5-O-methyltransferase in avermectin-producing Streptomyces avermitilis. Gene 206 175-180, 1998. 

H Ikeda, Y Takada, CH Pang, K Matsuzaki, H Tanaka, S Omura. Direct production of 5-oxo derivatives of avermectins by a recombinant strain of Streptomyces avermitilis. J Antibiot 48 95-97, 1995. 

Avermectin is produced by biotechnological methods with the aid of Streptomyces avermitilis. 

Avermectins are a group of closely related compounds isolated from the fungus Streptomyces avermitilis that are used to control the parasites of humans and animals, as well as arthropod pests in crops. They have fairly high mammalian toxicity, but their movement into treated leaves, oral activity against insect pests, and rapid breakdown in sunlight are all favorable properties. In insects and worms poisoned by avermectin, inactivity and flaccid paralysis occur from its relaxing effect on muscles. 

Avermectin B2a-23-one] Streptomyces avermitilis (actinomycete Atracurium is GABAA-R antagonist Laudanosine GABAA-R agonist [anti-... 

Abamectin is an insecticide/acaricide that contains a mixture of avermectin Bja (>80%) and avermectin Bjb (<20%) as active ingredients. Avermectins, which are macrocyclic lactones, are derived from the actinomycete, Streptomyces avermitilis (soil microorganism). It is used to control insect and mite pests of a wide range of agronomic, fruit, vegetable, and ornamental crops. It is also used by home owners for control of fire ants. It has an oral LD50 in rats of 300 mg/kg. 

Streptomyces avermitilis. The products (a mixture of the fermentation) is abamectin, the common name for products such as Avermectin , Affirm , or and Avid. ... 

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