Genetic engineering of aminodeoxyhexose biosynthesis in Streptomyces fradiae

Abstract

The antibacterial properties of macrolide antibiotics (such as erythromycin, tylosin, and narbomycin) depend ultimately on the glycosylation of otherwise inactive polyketide lactones. Among the sugars commonly found in such macrolides are various 6-deoxyhexoses including the 3-dimethylamino sugars mycaminose and desosamine (4-deoxymycaminose). Some macrolides (such as tylosin) possess multiple sugar moieties, whereas others (such as narbomycin) have only single sugar substituents. As patterns of glycosylation markedly influence a macrolide's drug activity, there is considerable interest in the possibility of using combinatorial biosynthesis to generate new pairings of polyketide lactones with sugars, especially 6-deoxyhexoses. Here, we report a successful attempt to alter the aminodeoxyhexose-biosynthetic capacity of Streptomyces fradiae (a producer of tylosin) by importing genes from the narbomycin producer Streptomyces narbonensis. This engineered S. fradiae produced substantial amounts of two potentially useful macrolides that had not previously been obtained by fermentation.

An Enzyme Module System for the Synthesis of dTDP‐activated Deoxysugars from dTMP and Sucrose

“…Isomerization of 3 at C-4 and C-3 with subsequent amination of the resulting C-3 carbonyl affords dTDP-3-amino-3,6-dideoxy-a-d-glucose (8), the precursor of dTDP-d-mycaminose and dTDP-d-desosamine. [24][25][26] The deoxygenation of 3 at C-2 and stereospecific reduction of the C-3 carbonyl produces dTDP-2,6-dideoxy-4-keto-d-glucose (9) or -d-allose (10). Both are important biosynthetic intermediates for the synthesis of dTDP-2,6-dideoxyhexoses.…”

Organization of the biosynthetic gene cluster for the macrolide antibiotic spiramycin in Streptomyces ambofaciens

“…This is mostly due to the development of semi-synthetic derivatives, for instance clarithromycin, azithromycin and more recently ketolides, with improvements to features such as stability, pharmacokinetics and activity against resistant bacteria (Schönfeld & Kirst, 2002). The characterization of macrolide biosynthetic gene clusters has opened the way to rational genetic yield improvement of production strains (Stratigopoulos et al, 2004) and to the development of combinatorial strategies for the synthesis of new macrolides (Butler et al, 2002; Abbreviations: NRPS, non-ribosomal peptide synthetase; PKS, polyketide synthase.…”

Hyper-inducible expression system for streptomycetes

“…These organisms have been very well studied, especially S. coelicolor (28,29) and S. avermitilis (30,31), for each of which the whole genome sequence has already been determined and extensive genomic information involving biosynthetic pathways for useful products or other metabolic pathways has been revealed. The combined application of the genomic information and regulated expression systems such as that described here could contribute to the systematic improvement of productivity in streptomycetes, for example, by enhancing the predicted rate-limiting steps of biosynthetic pathways (32)(33)(34)(35)(36)(37)(38). In the cases that the tsr gene in pSH19 is not ideal as a selection marker [e.g., the host strains are resistant to thiostrepton (3) or the addition of thiostrepton can induce a regulon of genes via the tipA system (3, 7)], an alternative selection marker that could be substituted for tsr would be preferable.…”