Nucleoside antibiotics. Asymmetric incorporation of glutamic acid and acetate into the maleimide ring of showdomycin by Streptomyces showdoensis

C‐Nucleosides are characterized by a C−C rather than a C−N linkage between the heterocyclic base and the ribofuranose ring. While the biosynthesis of pseudouridine‐C‐nucleosides has been studied, less is known about the pyrazole‐C‐nucleosides such as the formycins and pyrazofurin. Herein, genome screening of Streptomyces candidus NRRL 3601 led to the discovery of the pyrazofurin biosynthetic gene cluster pyf. In vitro characterization of gene product PyfQ demonstrated that it is able to catalyze formation of the C‐glycoside carboxyhydroxypyrazole ribonucleotide (CHPR) from 4‐hydroxy‐1H‐pyrazole‐3,5‐dicarboxylic acid and phosphoribosyl pyrophosphate (PRPP). Similarly, ForT, the PyfQ homologue in the formycin pathway, can catalyze the coupling of 4‐amino‐1H‐pyrazole‐3,5‐dicarboxylic acid and PRPP to form carboxyaminopyrazole ribonucleotide. Finally, PyfP and PyfT are shown to catalyze amidation of CHPR to pyrazofurin 5′‐phosphate thereby establishing the latter stages of both pyrazofurin and formycin biosynthesis.

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“… Proposed mechanism for pseudouridine synthase. The cosubstrate 13 in SdmA reaction is likely derived from l ‐glutamine …”

Section: Figurementioning

confidence: 99%

Identification of the C‐Glycoside Synthases during Biosynthesis of the Pyrazole‐C‐Nucleosides Formycin and Pyrazofurin

Ren

Wang

et al. 2019

Angewandte Chemie

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“…In the biosynthesis of pseudouridine, the intramolecular rearrangement in tRNA of uridylate to pseudouridylate has been strongly suggested.1-6) The biosynthesis of showdomycin has been well established and confirmed to occur by the condensation of ribose and an asymmetric four-carbon dicaboxylic acid. [7][8][9][10] Recently, studies on the biosynthesis of minimycin revealed a novel mechanism whereby C-riboside linkage is formed from sedoheptulose 7-phosphate (or eight-carbon branched chain sugar phosphate).11)…”

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confidence: 99%

Biosynthesis of formycin. Incorporation and distribution of labeled compounds into formycin.

et al. 1976

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1. Two carbons, carbon-2 and one of carbons-3 to -5, of lysine seemed likely to be incorporated into one of carbon of the chromophore moiety of formycin.2. From the results of radioisotopic studies with glutamate, r-amino-n-butyrate or organic acids related to tricarboxylic acid cycle, the important role of glutamate in the biosynthesis of formycin was strongly suggested.3. The incorporation of nitrogen(s) of lysine into three nitrogens, including two nitrogens of pyrazole ring, of formycin was suggested by mass spectroscopy. 4. Ribose was estimated as a direct precursor for the ribosyl moiety of formycin, whereas the biosynthesis of ribose was shown to occur via the pathway other than hexose monophosphate shunt or glucuronate pathway.5. In replacement culture, the salvage synthesis of formycin from its chromophore moiety was not observed and it was also evident that the chromophore moiety or pyrazofurin (pyrazomycin) inhibited the biosynthesis of formycin.There have been several investigations on the biosynthesis of C-riboside nucleosides, i.e., pseudouridine, showdomycin, minimycin, pyrazofurin (pyrazomycin) and the formycin family. In the biosynthesis of pseudouridine, the intramolecular rearrangement in tRNA of uridylate to pseudouridylate has been strongly suggested.1-6) The biosynthesis of showdomycin has been well established and confirmed to occur by the condensation of ribose and an asymmetric four-carbon dicaboxylic acid.7-10)Recently, studies on the biosynthesis of minimycin revealed a novel mechanism whereby C-riboside linkage is formed from sedoheptulose 7-phosphate (or eight-carbon branched chain sugar phosphate).11) C-Riboside linkage of pyrazofurin was also believed to be formed by this mechanism.11)The biosynthesis of formycin by Nocardia interforma has been proposed to occur via a pathway other than that of biosynthesis of purine nucleotide while exogeneously added ribose was estimated to be incorporated into the ribosyl moiety of formycin.12) It was also reported that formycin may be formed from formycin 5'-monophosphate then deaminated to formycin B.13) Using Streptomyces sp.MA406-A-1, a formycin-producing strain, we reported that carbon atom from lysine, glutamate and/or aspartate was incorporated into formycin with high efficiency, and that novel enzyme(s) catalyzing the amination of formycin B to formycin was present in this organism. 14,15) To elucidate the more detailed mechanism of formycin biosynthesis, we examined the incorporation and the distribution of various labeled compounds into formycin and this paper presents the results of these studies.

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“…First, the lowest field resonance showed extensive coupling to all of the other protons. In showdomycin, the nonexchangeable resonance at lowest field (H4) was coupled only to H,Second, the chemical shifts of the low-field proton (Darnall et al, 1967) and one vinyl carbon (Elstner et al, 1973;Elstner and Suhadolnik, 1972) (Table I) are considerably different from those which have been reported for showdomycin.…”

Section: Resultsmentioning

confidence: 89%

“…The inhibition of maleimycin and showdomycin is reversed by cysteine or glutathione. It had been established that C2-C5 of glutamate and -ketoglutarate serve as the asymmetric fourcarbon unit for C2-C5 of the maleimide ring of showdomycin (Elstner and Suhadolnik, 1972). Similarly, 14C-labeled maleimycin was isolated following the addition of either [2-14C]acetate or [5-14C]glutamate (Table VII).…”

Section: Resultsmentioning

confidence: 99%

Isolation, structural elucidation, biological properties, and biosynthesis of maleimycin, a new bicyclic maleimide antibiotic isolated from the culture filtrates of Streptomyces showdoensis. 14

Elstner¹,

Carnes²,

Suhadolnik³

et al. 1973

Biochemistry

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Maleimycin is a bicyclic maleimide antibiotic elaborated by Streptomyces showdoensis. The physical and chemical data show the structure for maleimycin to be 3aza-6-hydroxybicyclo[3.3.0]oct-Al iS-ene-2,4-dione. The nuclear magnetic resonance (nmr) spectra in DoO showed five welldefined resonances corresponding to the five nonexchangeable protons. The 13C spectra consisted of seven resonances: two resonances in the carbonyl region at -41.3 and -40.7 ppm, two resonances in the aromatic or unsaturated region at -29.3 and -23.7 ppm, and one resonance at +56.3 ppm During a study of showdomycin, a second ultraviolet absorbing compound was observed in the culture filtrates of Streptomyces showdoensis. This compound has been isolated and crystallized, and its physical and biological properties have been studied in much detail. By the use of H (proton) nuclear magnetic resonance (pmr) and 13C nmr (cmr), the resonances of the five nonexchangeable protons and the spectra of the seven carbons are described. It is now possible to report the structure of this new maleimide antibiotic as 3aza-6-hydroxybicyclo[3.3.0]oct-A15-ene-2,4-dione. The biochemical properties and biosynthesis are also described. Experimental ProcedureIsolation of Maleimycin. Cultures of S. showdoensis were grown for 42 hr as described by Elstner et al. (1973). The medium was filtered, passed through Dowex 50-X8 (H*) (20-50 mesh, 3 cm X 20 cm). The pH was adjusted to 4.5 (ammonium hydroxide), adsorbed on Norit A (10 g/L), and washed with 1 1. of water. Maleimycin was eluted batchwise with acetone-water (80:20, v/v) (three times, 500 ml each time). The eluent was concentrated under vacuum to 2 ml, spotted on four Whatman No. 3MM paper chromatograms t From the

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Nucleoside antibiotics. Asymmetric incorporation of glutamic acid and acetate into the maleimide ring of showdomycin by Streptomyces showdoensis

Cited by 26 publications

References 11 publications

Identification of the C‐Glycoside Synthases during Biosynthesis of the Pyrazole‐C‐Nucleosides Formycin and Pyrazofurin

Identification of the C‐Glycoside Synthases during Biosynthesis of the Pyrazole‐C‐Nucleosides Formycin and Pyrazofurin

Biosynthesis of formycin. Incorporation and distribution of labeled compounds into formycin.

Isolation, structural elucidation, biological properties, and biosynthesis of maleimycin, a new bicyclic maleimide antibiotic isolated from the culture filtrates of Streptomyces showdoensis. 14

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