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PubMed1984

Biosynthesis of astromicin and related antibiotics. I. Biosynthetic studies by bioconversion experiments.

Biosynthesis of astromicin, a unique pseudodisaccharide aminoglycoside antibiotic containing 1,4-diaminocyclitol component, was investigated by isolating a variety of possible precursor compounds from mutants of Micromonospora olivasterospora in which biosynthetic pathways for astromicin were blocked. Washed mycelia of M. olivasterospora mutants converted these compounds to astromicin, which was detected by thin-layer chromatography. Since astromicin possesses one glycyl and three methyl groups, [14C]glycine and [14C]methionine should be incorporated into precursors to form astromicin. To confirm the biosynthetic pathway, formation of labeled astromicin from the precursors was examined using [1-14C]-glycine or [methyl-14C]methionine. From above results, we propose the biosynthetic pathway for astromicin as shown in Fig. 2.

Aminoglycosides↗
PubMed1989

Calicheamicins, a novel family of antitumor antibiotics. 3. Isolation, purification and characterization of calicheamicins beta 1Br, gamma 1Br, alpha 2I, alpha 3I, beta 1I, gamma 1I and delta 1I.

Novel antitumor antibiotics, calicheamicins beta 1Br, gamma 1Br, alpha 2I, alpha 3I, beta 1I, gamma 1I and delta 1I were recovered from the fermentation broth of Micromonospora echinospora ssp. calichensis by solvent extraction, selective precipitation, normal phase, reversed phase and partition chromatography. The individual components were characterized by their UV, IR, 1H and 13C NMR spectral data.

Aminoglycosides↗
PubMed1989

Common biosynthetic feature of fortimicin-group antibiotics.

The fortimicin (FTM) group antibiotics are produced by actinomycetes belonging to various genera. FTM's and sannamycins are the products of Micromonospora olivasterospora and Streptomyces sannanensis, respectively. The possible presence of common features of the biosynthesis of these structurally related antibiotics in the two producers was examined. Enzymatic studies were done by the bioconversion experiments using FTM precursors and the washed cells of S. sannanensis. Ion pair/reverse-phase HPLC was employed as the analytical tool. S. sannanensis could convert almost all FTM precursors to the expected structures in the down stream of the pathway except one step. Thus the sets of the biosynthetic enzymes of the two bacteria share the common substrate specificity and react alternatively.

Aminoglycosides↗
PubMed1991

Dynemicins O, P and Q: novel antibiotics related to dynemicin A isolation, characterization and biological activity.

New antibiotics, dynemicins O (3), P (4) and Q (5), were isolated from the culture broth of Micromonospora chersina M956-1, the dynemicin A (1)-producing strain. An ethyl acetate extract of a tank culture was roughly separated by a column of Diaion SP-800 and was further purified by combining a variety of column chromatographies to afford a few mg of compounds 3, 4 and 5. Their structures, analyzed from the spectral data, had a bridging phenylene group, a vic-diol and an oxo group in place of the respective 1,5-diyn-3-ene bridge, the epoxide ring and the carboxyl group in dynemicin A. Their biological activities were evaluated against bacteria and tumor cells.

Alkenes↗
PubMed1991

Dynemicins, new antibiotics with the 1,5-diyn-3-ene and anthraquinone subunit. I. Production, isolation and physico-chemical properties.

Dynemicin A, a novel antibiotic containing the bicyclo[7.3.1]-1,5-diyn-3-ene and 1,4,6-trihydroxyanthraquinone functionalities, was isolated from the culture broth of Micromonospora chersina sp. nov. M956-1. The antibiotic exhibited potent in vitro antibacterial and cytotoxic activity, and in in vivo, it cured mice from lethal Staphylococcus aureus infection and prolonged survival time of mice inoculated with murine tumors. Three satellite components, dynemicins L, M and N, were also isolated from the culture broth and chemically characterized.

Animals↗
PubMed1992

Carbon catabolite regulation of gentamicin formation.

The effect of utilizable carbon sources on the production of gentamicin by Micromonospora purpurea has been studied. High D-glucose and D-xylose concentrations (40 mg/ml), exerted a strong and permanent negative action on antibiotic formation. On the other hand, similar concentrations of D-fructose, D-mannose, maltose and starch caused no effect. The glucose action is seen only if added during the logarithmic growth phase; moreover, the sugar needs to be metabolized to show its negative effect.

Carbohydrate Metabolism↗
PubMed1993

Isolation of trehalamine, the aglycon of trehazolin, from microbial broths and characterization of trehazolin related compounds.

Trehalamine, (3aR,4R,5S,6S,6aS)-2-amino-4-(hydroxymethyl)-3a,5,6,6a- tetrahydro-4H-cyclo-pent[d]oxazole-4,5,6-triol (1) and D-glucose were obtained by acid hydrolysis of trehazolin (3), a trehalase inhibitor produced by actinomycetes. More vigorous hydrolytic treatment of trehazolin afforded an aminocyclitol, (1R,2S,3R,4S,5R)-5-amino-1- (hydroxymethyl)cyclopentane-1,2,3,4-tetraol (2). Trehalamine, the aglycon of trehazolin, was also found in the culture broths of two trehazolin producing strains, Micromonospora sp. SANK 62390 and Amycolatopsis sp. SANK 60791. These trehazolin related compounds trehalamine (1) and 2 were poor inhibitors of trehalase (1; IC50 1.8 x 10(-4) M, 2; > 5.0 x 10(-4) M). On the other hand they inhibited more potently rat intestinal sucrase (1; IC50 6.8 x 10(-5) M) and sweet almond beta-glucosidase (2; IC50 5.6 x 10(-6) M) than trehazolin.

Actinobacteria↗
PubMed1993

Quinolidomicins A1, A2 and B1, novel 60-membered macrolide antibiotics. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activity.

Three novel macrolide antibiotics, quinolidomicins A1, A2 and B1, were isolated from the fermentation broth of Micromonospora sp. JY16. Quinolidomicin A1 inhibited the growth of various tumor cells including multidrug-resistant cells. Quinolidomicin B1 was similarly cytotoxic, while quinolidomicin A2 was inactive against these tumor cells.

Animals↗
PubMed1994

Cororubicin, a new anthracycline antibiotic generating active oxygen in tumor cells.

In the course of our screening for antitumor antibiotics which show biological activities by generating active oxygen in tumor cells. Micromonospora sp. JY16 was found to produce a new anthracycline antibiotic designated cororubicin. The structure of cororubicin was elucidated as shown in Fig. 5 on the basis of NMR spectral analysis. Cororubicin generated superoxide radicals in tumor cells and showed cytotoxicity, which was reduced by addition of an antioxidative agent, dithiothreitol (DTT).

Anthracyclines↗
PubMed1994

Physiological studies on gentamicin: phosphate repression of antibiotic formation.

The effect of inorganic phosphate on the fermentative production of gentamicin by Micromonospora purpurea has been studied using a chemically defined medium. Phosphate concentrations higher than 5.75 mM (1 g/liter-1) did not inhibit growth but specifically prevented antibiotic formation. Changes in the pH medium and carbon or nitrogen depletion were excluded as the cause of antibiotic underproduction. The use of a phosphate analogue, a protein synthesis inhibitor and the profiles of differential rate of antibiotic production suggested that phosphate itself transiently repressed gentamicin formation. Phosphate affected the formation of 2-deoxystreptamine from 2-deoxyinosose, a none phosphorylated substrate.

Arsenates↗
PubMed1997

Cymbimicin A and B, two novel cyclophilin-binding structures isolated from actinomycetes.

Two novel metabolites, cymbimicins A and B, were isolated from the culture broth of a strain of Micromonospora sp. by screening for cyclophilin binding metabolites from actinomycete strains. Cymbimicin A binds to cyclophilin A with a high affinity six fold lower than to that of cyclosporin A. The binding affinity of cymbimicin B is about 100 times lower. The taxonomy of the producing strain, fermentation, isolation, physical and biological properties and structure elucidation are described.

Binding, Competitive↗
PubMed2002

Biosynthesis of the trehalase inhibitor trehazolin.

Trehazolin (1) is a trehalase inhibitor produced by Micromonospora coriacea. Biosynthesis of 1 was studied by feeding experiments with a variety of labeled precursors. Feeding experiments with [1-13C]- and [6-13C]-D-glucose revealed that the carbon skeletons of both a glucose residue and a cyclopentane ring moiety in 1 were each derived from glucose, and that C-C bond formation between C-1 and C-5 of glucose occurred during the cyclopentane ring formation. Furthermore, an experiment with [guanidino-13C, 15N2]-L-arginine revealed that two nitrogen atoms and a quaternary carbon atom involved in the aminooxazoline moiety of 1 originated from an amidino group of arginine. Further feeding experiments with [1-2H]-, [2-2H]-, [4-2H]-, [6,6-2H2]- and [1,2,3,4,5,6,6-2H7]-D-glucose as well as [1-13C]-D-fructose showed that deuteriums on C-1, C-3, C-4 and C-6 of glucose were retained during the formation of the cyclopentane ring moiety of 1.

Culture Media↗
PubMedDate not supplied

[The biodiversity of actinomycetes in Lake Baikal].

The taxonomic analysis of 107 actinomycete strains isolated from the bottom sediments and water of Lake Baikal showed that most of the water isolates belong to the genus Streptomyces and most of the sediment isolates belong to the genus Micromonospora. In the sediments, the number of actinomycetes increased with depth (down to 200 m). Eight Streptomyces isolates were identified to a species level.

Actinomycetales↗
PubMedDate not supplied

[Antagonistic activity of actinomycetes of Lake Baikal].

It was demonstrated that actinomycetes of Lake Baikal are strong antagonists of other microorganisms. Representatives of the genera Streptomyces and Micromonospora inhibit the growth of bacteria isolated from the lake, as well as of antibiotic-resistant microorganisms causing various human diseases. Baikal actinomycetes display a wide range of antagonistic activity and are potential producers of new biologically active substances.

Actinobacteria↗
PubMed1989

[Effect of the oxidation-reduction potential of the medium on the production of gentamycin].

The medium redox potential had an effect on gentamicin production by Micromonospora purpurea v. violacea, strain VNIIA 7R. The Eh influence was shown to be statistically reliable when the results were expressed in relative units against the control. In the laboratory experiments with low volumes of the medium the Eh increase by more than 170 per cent induced inhibition of gentamicin biosynthesis while the Eh increase by 108 to 168 per cent induced stimulation of the activity.

Culture Media↗
PubMed1995

Inhibitors of pig kidney trehalase.

Trehazolin, a new trehalase inhibitor isolated from the culture broth of Micromonospora, was reported to be a highly specific inhibitor for porcine and silk worm trehalases with IC50 values of 5.5 x 10(-9) and 3.7 x 10(-9) M, respectively (O. Ando, H. Satake, K. Itoi, A. Sato, M. Nakajima, S. Takashi, H. Haruyama, Y. Ohkuma, T. Kinoshita, and R. Enokita (1991) J. Antibiot. 44, 1165-1168). We also found that trehazolin is a very powerful and quite specific inhibitor against purified pig kidney trehalase, giving an IC50 value of 1.9 x 10(-8) M. Lineweaver-Burk plots showed that this compound was a competitive inhibitor of the trehalase. However, even at concentrations of 200 micrograms/ml, trehazolin did not inhibit the rat intestinal maltase or sucrase, yeast alpha-glucosidase or almond beta-glucosidase. Validoxylamine A and validamycin A, two other trehalase inhibitors, showed potent competitive inhibition against purified pig kidney trehalase, with IC50 values of 2.4 x 10(-9) and 2.5 x 10(-4) M, respectively. On the other hand, validoxylamine A was almost inactive against rat intestinal sucrase and maltase, with some inhibition being observed at millimolar concentration. A number of other glucosidase inhibitors, such as MDL 25637, castanospermine, and deoxynojirimycin were also tested against the purified trehalase and showed reasonable inhibitory activity.

1-Deoxynojirimycin↗
PubMed1995

Red cells bound to influenza virus N9 neuraminidase are not released by the N9 neuraminidase activity.

Influenza virus neuraminidase (NA) of the N9 subtype also possesses hemagglutinin activity and the hemagglutinating, or hemabsorbing (HB), site is distinct from the catalytic site. Previous results suggested that the NA was binding to sialic acid on the red cell surface, but we now report that the HB receptor is not sensitive to N9 influenza neuraminidase activity. Cell lines that constitutively express N9 or N2 neuraminidase have been used to further investigate the specificity of red blood cell binding to the HB site. The results suggest that the ligand is N-acetylneuraminic acid in a linkage or environment that is not sensitive to influenza virus neuraminidase, but which is released by the broadly specific bacterial sialidases from Micromonospora viridifaciens or Arthrobacter ureafaciens.

Animals↗