Mutational biosynthesis by idiotrophs of Micromonospora purpurea. I. Conversion of aminocyclitols to new aminoglycoside antibiotics.

Rosi, D.; Goss, William A.; Daum, Sol J.

doi:10.7164/antibiotics.30.88

Cited by 36 publications

(15 citation statements)

References 27 publications

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“…The aminotransferase will accept inosose and inosamine substrates with a hydroxyl group present at position 2 of the cyclitol ring. This is consistent with in vivo studies (9,22) in which a 2-deoxystreptamine-less idiotroph of a gentamicin producer incorporated keto-scyllo-inositol or aminodeoxyscyllo-inositol into 2-hydroxygentamicin. A similar tolerance for either the presence or absence of a 2-hydroxyl on the cyclitol substrate has been observed with the aminotransferase of neomycin-producing S. fradiae (5), with the aminotransferase of the bluensidine pathway (26), and with both aminotransferases of the streptidine pathway (27).…”

Section: Discussionsupporting

confidence: 78%

Reactions catalyzed by purified L-glutamine: keto-scyllo-inositol aminotransferase, an enzyme required for biosynthesis of aminocyclitol antibiotics

Lucher

Chen

Walker

1989

Antimicrob Agents Chemother

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Dialyzed extracts of the gentamicin producer Micromonospora purpurea catalyze reactions which represent transaminations proposed for 2-deoxystreptamine biosynthesis. To determine whether these transaminations were catalyzed by a single aminotransferase or by multiple enzymes, we purified and characterized an L-glutamine:keto-scyllo-inositol aminotransferase from M. purpurea. This enzyme was purified 130-to 150-fold from late-log-phase mycelia of both wild-type M. purpurea and a 2-deoxystreptamine-less idiotroph. The cofactor pyridoxal phosphate was found to be tightly bound to the enzyme, and spectral analysis demonstrated its participation in the transamination reactions of this enzyme. The major physiological amino donor for the enzyme appears to be L-glutamine; the keto acid product derived from glutamine was characterized as 2-ketoglutaramate, indicating that the alpha amino group of glutamine participates in the transamination. We found that crude extracts contained omega-amidase activity, which may render transaminations with glutamine irreversible in vivo. The substrate specificity of the aminotransferase was shown to be restricted to deoxycyclitols, monoaminocyclitols, and diaminocyclitols, glutamine, and 2-ketoglutaramate, which contrasts with the broader substrate specificity of mammalian glutamine aminotransferase. The appearance of the enzyme in late-log phase, coupled with its narrow substrate specificity, indicates that it participates predominantly in 2-deoxystreptamine biosynthesis rather than in general metabolism. The enzyme catalyzes reactions which represent both transamination steps of 2-deoxystreptamine biosynthesis. Although copurification of two aminotransferases cannot be ruled out, our data are consistent with the participation of a single aminotransferase in the formation of both amino groups of 2-deoxystreptamine during biosynthesis by M. purpurea. We propose that this aminotransferase participates in a key initial step in the biosynthesis of most aminocyclitol antibiotics.2-Deoxystreptamine is a component of numerous clinically important antibiotics such as gentamicin, neomycin, tobramycin, amikacin, and hygromycin, while streptamine is known to occur naturally in place of 2-deoxystreptamine in at least one member (SS-56C) of the destomycin group (for reviews, see references 19 and 21). A pathway for 2-deoxystreptamine biosynthesis has been proposed (Fig. 1) on the basis of mutasynthesis and isotopic competition studies (9, 13) and in vitro enzymatic studies (5). The two aminotransferase steps of this pathway may be analogous to the two transaminations which occur in the biosynthesis of the streptidine moiety of streptomycin (27). These reactions in streptidine biosynthesis are catalyzed by separate enzymes; L-glutamine:keto-scyllo-inositol aminotransferase (glutamine-scyllo-inosose aminotransferase; EC 2.6.1.50) catalyzes the first transamination reaction (26). This enzymatic activity has also been detected in extracts of actinomycetes that produce bluensomycin (26) and the 2-deoxys...

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Section: Discussionsupporting

confidence: 78%

Reactions catalyzed by purified L-glutamine: keto-scyllo-inositol aminotransferase, an enzyme required for biosynthesis of aminocyclitol antibiotics

Lucher

Chen

Walker

1989

Antimicrob Agents Chemother

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“…12) was also converted to an antibiotic by the mutant of M. purpurea (DAUM et al, 1977) and it seems reasonable to speculate that this was a result of vibo-quercitol oxidation to produce 2,4/3,5-tetrahydroxycyclohexanone, which was used for deoxystreptamine biosynthesis followed by incorporation into gentamicin. 12) was also converted to an antibiotic by the mutant of M. purpurea (DAUM et al, 1977) and it seems reasonable to speculate that this was a result of vibo-quercitol oxidation to produce 2,4/3,5-tetrahydroxycyclohexanone, which was used for deoxystreptamine biosynthesis followed by incorporation into gentamicin.…”

Section: Neomycin and Paromomycinmentioning

confidence: 99%

“…12) was also converted to an antibiotic by the mutant of M. purpurea (DAUM et al, 1977) and it seems reasonable to speculate that this was a result of vibo-quercitol oxidation to produce 2,4/3,5-tetrahydroxycyclohexanone, which was used for deoxystreptamine biosynthesis followed by incorporation into gentamicin. A possible solution to this dichotomy would be to repeat the experiments of DAUM et al (1977) using resolved D-and L-vibo-quercitol and 2,4/3,5-tetrahydroxycyclohexanone Biosynthesis of Aminocyclitol Antibiotics 83 in order to ascertain which isomer is the precursor for gentamicin biosynthesis and, therefore, 2-deoxystreptamine. Although in this figure C-3 is aminated prior to C-l, which contrasts with streptidine biosynthesis where C-l is aminated prior to C-3, whether this is the actual order of amination is uncertain.…”

Section: Neomycin and Paromomycinmentioning

confidence: 99%

Biosynthesis

1981

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“…A less toxic aminoglycoside would provide an agent that could be used with reduced risk, especially in patients with impaired kidney function. We now report on studies with such an aminoglycoside antibiotic that was prepared by mutational biosynthesis and designated Win 42122-2 (11). This report presents results of in vitro and in vivo microbiological evaluations ofWin 42122-2 and the results of toxicity studies in rats, guinea pigs, and cats.…”

mentioning

confidence: 99%

Antibacterial activities, nephrotoxicity, and ototoxicity of a new aminoglycoside, Win 42122-2

Came¹,

O'Connor²,

Dobson³

et al. 1979

Antimicrob Agents Chemother

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Win 42122-2 is a new aminoglycoside antibiotic obtained from a mutant strain of Micromonospora purpurea. In vitro and in vivo comparisons of Win 42122-2 with gentamicin and amikacin revealed that Win 42122-2 generally was less active than gentamicin against Pseudomonas and many Enterobacteriacae, especially Klebsiella and indole-negative Proteus. Against most gentamicin-susceptible isolates, Win 42122-2 was more active than amikacin. Gentamicin-resistant clinical isolates were usually resistant to Win 42122-2, although it was active against certain gentamicin-resistant organisms, depending upon the aminoglycoside-modifying enzymes harbored by the organism. However, Win 42122-2 was markedly less toxic than gentamicin in subacute nephrotoxicity studies in rats, ototoxicity experiments in guinea pigs, and ataxia determinations in cats. This series of antibacterial determinations and toxicity evaluations indicated that the reduced toxicity of the antibiotic may be sufficient to provide an improved therapeutic ratio over gentamicin and other aminoglycosides, even though Win 42122-2 is less potent than gentamicin against some bacteria.

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Mutational biosynthesis by idiotrophs of Micromonospora purpurea. I. Conversion of aminocyclitols to new aminoglycoside antibiotics.

Cited by 36 publications

References 27 publications

Reactions catalyzed by purified L-glutamine: keto-scyllo-inositol aminotransferase, an enzyme required for biosynthesis of aminocyclitol antibiotics

Reactions catalyzed by purified L-glutamine: keto-scyllo-inositol aminotransferase, an enzyme required for biosynthesis of aminocyclitol antibiotics

Biosynthesis

Antibacterial activities, nephrotoxicity, and ototoxicity of a new aminoglycoside, Win 42122-2

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