Engineering validamycin production by tandem deletion of γ-butyrolactone receptor genes in Streptomyces hygroscopicus 5008

Abstract

Paired homologs of γ-butyrolactone (GBL) biosynthesis gene afsA and GBL receptor gene arpA are located at different positions in genome of Streptomyces hygroscopicus 5008. Inactivation of afsA homologs dramatically decreased biosynthesis of validamycin, an important anti-fungal antibiotic and a critical substrate for antidiabetic drug synthesis, and the deletion of arpA homologs increased validamycin production by 26% (ΔshbR1) and 20% (ΔshbR3). By double deletion, the ΔshbR1/R3 mutant showed higher transcriptional levels of adpA-H (the S. hygroscopicus ortholog of the global regulatory gene adpA) and validamycin biosynthetic genes, and validamycin production increased by 55%. Furthermore, by engineering a high-producing industrial strain via tandem deletion of GBL receptor genes, validamycin production and productivity were enhanced from 19 to 24 g/L (by 26%) and from 6.7 to 9.7 g/L(-1) d(-1) (by 45%), respectively, which was the highest ever reported. The strategy demonstrated here may be useful to engineering other Streptomyces spp. with multiple pairs of afsA-arpA homologs.

Novel spectrophotometric approach for determination of validamycin A in fermentation of Streptomyces hygroscopicus

“…Meanwhile, ethanol or temperature shift in fermentation could increase Val-A production (2,10,14). In latest research, addition of 1,4-butyrolactone could also affect metabolic pathway in S. hygroscopicus 5008 (9). Streptomyces fermentation could be influenced by the medium pH obviously, and the secondary metabolism could also be affected (15).…”

“…Different culture conditions included: (i) Fermentation with ethanol and 1,4-butyrolactone. They were added with a final concentration that can achieve the best production of Val-A as the references mentioned (2,9). The purpose is to study the relationship between the pigment and Val-A productivity when an exogenous stimulant which has been proved to enhance Val-A production is added.…”

Engineering microbial hosts for production of bacterial natural products

“…149, 150 Tandem deletion of two GBL receptors in S. hygroscopicus increased validomycin titers and productivity by up to 26% (24 g/L) and 45% (9.7 g/L/day), respectively, which are the highest reported values to date. 151 A few studies have suggested that disruption of GBL receptors may negatively affect antibiotic production, though the lower titers observed may be a result of increased production of other secondary metabolites competing for the same biosynthetic precursors. 148 Although GBL identification is hindered by the fact that they are produced at minute levels and our incomplete knowledge of their biosynthesis, GBL receptors and their homologs can be easily identified by sequence analysis.…”

Similarity and dissimilarity of primary structures of some Streptomyces spp. genomes and the Streptomyces globisporus 1912-2 chromosomal DNA.

“…Nowadays many efforts are made to estimate this potential and to get access to the natural products, the biosynthetic pathways of which are encoded in the genomes of the corresponding Streptomyces strains [13][14][15]. The accumulation of high quality genome sequencing data will strongly contribute to implementation of this task [3,4,[6][7][8][9][10][11].…”