Nucleoside intermediates in blasticidin S biosynthesis identified by the in vivo use of enzyme inhibitors

Abstract

s . Can. J. Chem. 72,6 (1994).Intermediates in the biosynthesis of blasticidin S and its nucleoside co-metabolites were detected by altering fermentation conditions. Inhibitors of specific types of biochemical reactions that were expected to be involved in blasticidin biosynthesis were fed to Streptomyces griseochromogenes, in some cases with the inclusion of large quantities of the primary precursors of blasticidin S. The types of reactions and inhibitors used were (1) transaminase (aminooxyacetic acid and 2-methylglutamate), (2) amidotransferase (azaserine and 6-diazo-5-0x0-L-norleucine), (3) arginine biosynthesis (arginine hydroxamate), and (4) methyltransferase (ethionine). These manipulations apparently distorted the pools of precursors and (or) intermediates, and led to substantial accumulations of three known, previously minor, metabolites of S. griseochromogenes, cytosylglucuronic acid, pentopyranine C, and demethylblasticidin S, and of two new ones, pentopyranone and isoblasticidin S. New cytosyl metabolites were detected by HPLC with photodiode array detection. Fermentations to which arginine hydroxamate and cytosine had been added also produced three aberrant metabolites that were derived from pentopyranone and arginine hydroxamate. [Traduit par la redaction]

The Blasticidin S Biosynthesis Gene Cluster from Streptomyces griseochromogenes: Sequence Analysis, Organization, and Initial Characterization

“…An intriguing feature of blasticidin S biosynthesis is that free cytosine is incorporated at exceptionally high levels (around 95 %)26 and the addition of exogenous cytosine can greatly increase CGA levels (up to 70‐fold) while having a modest effect on blasticidin S production (1.6‐fold) 44. Hence, it appears that the availability of free cytosine may be a limiting factor in blasticidin S biosynthesis.…”

A New Cytosine Glycoside from Streptomyces griseochromogenes Produced by the Use in Vivo of Enzyme Inhibitors

“…As part of our work to elucidate the intermediates between CGA ( 3 ) and cytosinine ( 4 ), and to explore the relationships between the various cytosinyl metabolites, the in vivo utilization of known inhibitors of enzymes expected to function in the biosynthesis of 1 was investigated. This proved to be an effective approach to study the biosynthesis of 1 , resulting in accumulated intermediates and the enhanced production of other cytosinyl metabolites. , Here, we report additional in vivo inhibitor studies leading to the production of a new cytosine nucleoside, 7 .

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“…This proved to be an effective approach to study the biosynthesis of 1, resulting in accumulated intermediates and the enhanced production of other cytosinyl metabolites. 19,20 Here, we report additional in vivo inhibitor studies leading to the production of a new cytosine nucleoside, 7.…”

“…Scheme 2), CGA (3), and demethylblasticidin S (5) were detected when appropriate inhibitors were incubated. 19 One new metabolite, however, having a cytosine chromophore was reproducibly detected in fermentations containing either argininic acid or R-methylaspartate along with added cytosine. This unidentified metabolite was purified from a preparative-scale fermentation of S. griseochromogenes using ion-exchange, size-exclusion, and reversed-phase chromatography.…”

“…Pentopyranine C ( 8 ; cf . Scheme ), CGA ( 3 ), and demethylblasticidin S ( 5 ) were detected when appropriate inhibitors were incubated . One new metabolite, however, having a cytosine chromophore was reproducibly detected in fermentations containing either argininic acid or α-methylaspartate along with added cytosine.…”