Changes in GE2270 antibiotic production in Planobispora rosea through modulation of methylation metabolism

Abstract

Thiazolylpeptide GE2270 is a potent antibiotic inhibiting protein synthesis in Gram-positive bacteria. It is produced as a complex of 10 related metabolites, differing mainly in the degree of methylation, by fermentation of the rare actinomycete Planobispora rosea ATCC 53773. Addition of vitamin B12 to the fermentation medium doubled total complex production and markedly changed the relative production of the various GE2270 metabolites, enhancing the biosynthesis of the more methylated component A. Among methylation inhibitors, the addition of sinefungin increased the amount of factor D2, which differs from component A in the lack of a methyl group. Since sinefungin is an S-adenosyl-L-methionine methyltransferase-specific inhibitor, these results indicate that the methylation step converting D2 into A involves an S-adenosyl-L-methionine methyltransferase. Simultaneous supplementation of vitamin B12 and sinefungin led to a twofold increase in D2 concentration, showing that vitamin B12, in addition to having an effect on the late methylation step, exerts a stimulating action on antibiotic backbone synthesis. This is possibly due to its role in an unusual pathway of serine synthesis peculiar to P. rosea metabolism. Finally, fermentation medium modifications were shown to be useful for the production of industrially valuable levels of components A or D2 in the GE2270 complex as starting points for the production of new interesting semi-synthetic antibiotics.

Antibiotic production improvement in the rare actinomycete Planobispora rosea by selection of mutants resistant to the Aminoglycosides Streptomycin and Gentamycin and to Rifamycin

“…As previously reported, the addition of Vitamin B12 to the fermentation medium directed GE2270 complex production toward the selective synthesis of factor A [5]. Thus, data herein reported refer to GE2270 factor A production.…”

“…P. rosea PR1/5 was isolated by N-methyl-N¢-nitro-Nnitrosoguanidine (MNNG) (Fluka, Buchs, Switzerland) treatment from the natural variant PR9/1 [5]. Spontaneous resistant mutants of strain PR1/5 (and selected derivatives) arose with frequencies between 10 À7 -10 À9 and were selected by spreading sonicated hyphae, prepared according to Beltrametti et al [2], on plates supplemented with 200 mg/l streptomycin (Sigma-Aldrich, St. Louis, MO, USA), 100 mg/l rifamycin (Sigma-Aldrich) or 1 mg/l gentamycin (Sigma-Aldrich).…”

“…Growth conditions in liquid media were essentially as described by Gastaldo and Marinelli [5]. CaCO 3 (Carlo Erba, Milan, Italy), 1; pH 7, deionized water up to 1 liter) in 500-ml baffled flasks.…”

“…As standard for antibiotic titre determination, a sample of GE2270 antibiotic was used. GE2270 production was calculated as already described [5].…”

Effect of cobalt and vitamin B12 on the production of salinosporamides by Salinispora tropica

“…7 Numerous reports on the increase in production of methylated antibiotics and the decrease in production of demethylated antibiotics by the addition of cobalt or vitamin B 12 to fermentation have been reported. [10][11][12][13] All the above methylated antibiotics require methionine as methyl donor. Using [13C-methyl]-methionine in a feeding study experiment, we found that the methyl group of methionine did not incorporate into NPI-0047 and NPI-0052 (data not shown).…”