Hybrid biosynthesis of derivatives of protylonolide and M-4365 by macrolide-producing microorganisms.

Abstract

Biotransformation of a macrolide antibiotic and a related compound was studied using various macrolide-producing microorganisms grown in the presence of cerulenin, an inhibitor of de novo synthesis of the aglycone moiety. Protylonolide (1) was transformed into 5-0-(4'-O-propionylmycarosyl)protylonolide (2) by a leucomycin-producing strain, Streptoverticillium kitasatoensis KA-429. M-4365 G2 (3) was bioconverted into M-4365 G3 (4), 9-dihydro M-4365 G3 (5), 3-O-acetyl M-4365 G3 (6) and 3-O-acetyl-9-dihydro M-4365 G3 (7) by a spiramycinproducing strain, Streptomyces ambofaciens KA-1028. Forosaminylated derivatives of M-4365 G2 were not obtained using this microorganism.M-4365 G2 was converted into 3-O-acetyl M-4365 G2 (8) by Stv. kitasatoensis strain KA-429 and a carbomycin-producing strain, S. thermotolerans KA-442.These results suggest that the substrate specificity of mycaminose-and forosamine-binding enzymes is high in Stv. kitasatoensis and S. ambofaciens, respectively, while that of the 3-hydroxyl acylating enzyme and mycarose-binding enzyme is low in these microorganisms.The bioconversion products showed lower antibacterial and antimycoplasmal activities than those of M-4365 G2.Many attempts have been made to obtain new antibiotic derivatives by adding the analogues of biosynthetic intermediates into the culture of an antibiotic producer or its mutant strains.The compounds thus obtained are utilized to study structure-activity relationships of the antibiotic. When an idiotroph, which requires the intermediate for the antibiotic biosynthesis, is used, this technique is called mutasynthesis or mutational biosynthesis.1)In a previous paper,2) we reported the hybrid biosynthesis of 5-O-desosaminylprotylonolide (identical with the antibiotic M-4365 G1) by adding protylonolide, a product of a mutant of a tylosin-producing strain,3) to the culture of a producer of picromycin, a macrolide with desosamine as its sugar moiety.Cerulenin was added to the growing culture to inhibit de novo synthesis of the aglycone moiety of picromycin.Using the technique of hybrid biosynthesis, five new bioconversion products were obtained from protylonolide or from antibiotic M-4365 G2, a product of Micromonospora capillata MCRL 0940,4) by three macrolide-producing microorganisms, Streptoverticillium kitasatoensis** KA-429 (a leucomycin producer), S. ambofaciens KA-1028 (a spiramycin producer) and S. thermotolerans KA-442 (a carbomycin producer) grown in the presence of cerulenin. The present paper describes the isolation, structures and biological activities of the new conversion products. The results are discussed with regard to the substrate specificity of the enzymes involved in the macrolide biosynthesis.t Bioconversion and biosynthesis of 16-membered macrolide antibiotics. XXIII.

Production of new hybrid antibiotics, mederrhodins A and B, by a genetically engineered strain

“…Production of novel antibiotics by mutasynthesis (15) or hybrid biosynthesis (10,11,13) is an interesting approach to the discovery of new antibiotics. Such methods are easily applied to obtain new antibiotics, but their fermentations need at least two processes: (i) cultivation of an idiotrophic mutant or an antibiotic-producing strain by the addition of an enzyme inhibitor and (ii) the addition of an analog of a biosynthetic intermediate.…”

“…These include mutasynthesis (15), in which an unnatural precursor is fed to an idiotroph genetically blocked in antibiotic biosynthesis, and hybrid biosynthesis (10,11,13), in which a wild-type strain is fed with such a precursor in the presence of an enzyme inhibitor which phenotypically blocks the biosynthetic pathway of the recipient strain. Another approach to the production of novel antibiotics is interspecific mating (9,14) or protoplast fusion (4,5).…”

Philosophy of new drug discovery.

“…Figure 37 shows the biosynthesis of nanaomycin and the site of action of cerulenin. Taking advantage of this mechanism of action, we have obtained a number of hybrid antibiotics (80,99,100).…”

Biotransformation of Rosamicin Antibiotic into 10,11-Dihydrorosamicin with Enhanced In Vitro Antibacterial Activity Against MRSA

“…It displays fair and broad-spectrum antibacterial properties, although it is more potent against gram-positive pathogens [3]. There have been some reports regarding the microbial biotransformation of this antibiotic [1,2,5,6,11]. Supplementation of the chemically de-epoxidized aglycone of rosamicin into a randomly mutated strain of mycinamicin-producing Micromonospora polytrota provided new derivatives of rosamicin, such as mycinosyl deoxysugar-attached rosamicins [6].…”

“…Recent studies have reported that the above mycinosyl rosamicin derivative could be produced by a genetically engineered recombinant of M. rosaria in which the gene set responsible for the biosynthesis and attachment of mycinose was introduced [1,2,5]. In addition, structural modification of a biosynthetic precursor of rosamicin, M-4365 G2, using various macrolide-producing microorganisms has been reported, with attachment of the acetyl group at the C3 hydroxyl position and reduction of the carbonyl function at the C9 position [11]. However, none of the above-described rosamicin analogs exhibited higher antibacterial activity than the parent rosamicin.…”