K-259-2, a new inhibitor of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase from Micromonospora olivasterospora

K-259-2, a new inhibitor of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase, was isolated from the cultured broth of Micromonospora olivasterospora K-259. K-259-2 has an anthraquinone moiety in its structure. IC50 values for the effect of K-259-2 against Ca2+ and calmodulin-stimulated activity of the enzyme preparations from bovine brain and heart were 6.6 and 2.9 microM, respectively. On the other hand, basal activity (the activity in the presence of ethylene bis(oxyethylenenitrilo)tetraacetic acid (EGTA) instead of Ca2+/calmodulin) of the bovine brain enzyme, calmodulin-independent cyclic nucleotide phosphodiesterase from bovine heart, and protein kinase C from rat brain were inhibited by K-259-2 to a lesser extent with IC50 values of 27.4, 40.7 and 45.8 microM, respectively.

K252a, a new inhibitor of protein kinase C, concomitantly inhibits 40K protein phosphorylation and serotonin secretion in a phorbol ester-stimulated platelets

K252a isolated from microbial origin was found to potently inhibit protein kinase C in vitro (1). This agent inhibits phosphorylation of 40,000 dalton protein (40K protein) induced by 12-0-tetradecanoylphorbol-13-acetate(TPA) in intact rabbit platelets. This indicates that K252a exhibits the inhibition of protein kinase C in intact cells. The serotonin secretion induced by TPA was inhibited by K252a at nearly equal concentrations required to inhibit the phosphorylation of 40K protein. This provides the evidence to support the cause-effect relationship between the protein phosphorylation and the secretion in TPA-stimulated platelets.

K-13, a novel inhibitor of angiotensin I converting enzyme produced by Micromonospora halophytica subsp. exilisia. I. Fermentation, isolation and biological properties

A novel inhibitor of angiotensin I converting enzyme (ACE), designated K-13, was isolated from the culture broth of Micromonospora halophytica subsp. exilisia K-13. K-13 inhibited ACE non-competitively when hippuryl-L-histidyl-L-leucine was used as a substrate. The inhibition constant (Ki) was 0.349 microM. K-13 hardly inhibited carboxypeptidase A, trypsin, alpha-chymotrypsin, leucine aminopeptidase, and aminopeptidase B even at a level of 61 microM. When K-13 was administered intravenously to rats, it inhibited the pressor response to angiotensin I.

K-252 compounds, novel and potent inhibitors of protein kinase C and cyclic nucleotide-dependent protein kinases

K-252 compounds (K-252a and b isolated from Nocardiopsis sp. (1) and their synthetic derivatives) were found to inhibit cyclic nucleotide-dependent protein kinases and protein kinase C to various extents. The inhibitions were of the competitive type with respect to ATP. K-252a was a non-selective inhibitor for these three protein kinases with Ki values 18-25 nM. K-252b showed a comparable potency for protein kinase C (Ki, 20nM), whereas inhibitory potencies for cyclic nucleotide-dependent protein kinases were reduced. KT5720 and KT5822 selectively inhibited cAMP-dependent (Ki, 60nM) and cGMP-dependent (Ki, 2.4nM) protein kinases, respectively.

K-252b, c and d, potent inhibitors of protein kinase C from microbial origin

Nocardiopsis sp. K-290 was found to produce novel metabolites, designated K-252b, c and d, which were structurally related to K-252a. These compounds were isolated from the culture broth and the physico-chemical and biochemical properties were examined. The compounds strongly inhibited protein kinase C. IC50 values (the concentrations causing 50% inhibition) for the effects of K-252b, c and d on the rat brain enzyme were 38.3, 214, and 337 nM, respectively.

Studies on lipoxygenase inhibitors. II. KF8940 (2-n-heptyl-4-hydroxyquinoline-N-oxide), a potent and selective inhibitor of 5-lipoxygenase, produced by Pseudomonas methanica

Pseudomonas methanica KY4634 was found to produce 5-lipoxygenase inhibitor designated KF8940, MY12-62a and MY12-62c. The inhibitors were purified by solvent extraction, silica gel column chromatography, reversed-phase low pressure liquid chromatography and crystallization. The chemical structures of KF8940, MY12-62a and MY12-62c were determined to be 2-n-heptyl-4-hydroxyquinoline-N-oxide, 2-n-heptyl-4-hydroxyquinoline and 3-n-heptyl-3-hydroxy-1,2,3,4-tetrahydroquinoline-2,4-dione, respectively, on the basis of their physico-chemical properties. Among them, KF8940 was the most potent inhibitor. The compound inhibited 5-lipoxygenase of rat basophilic leukemia cells in a dose-dependent manner and the half maximal inhibitory concentration (IC50) was 1.5 X 10(-7) M. At this concentration, KF8940 did not inhibit bovine platelet 12-lipoxygenase and cyclooxygenase, and the IC50 values for these enzyme were 3.5 X 10(-5) M and 1.7 X 10(-4) M, respectively. The results indicated that KF8940 is a potent and selective inhibitor of 5-lipoxygenase. The IC50 value of MY12-62c for 5-lipoxygenase was 1.9 X 10(-5) M and that of MY12-62a was 1.9 X 10(-5) M.

K-252a, a potent inhibitor of protein kinase C from microbial origin

K-252a, a metabolite isolated from the culture broth of Nocardiopsis sp. K-252a, was found to exhibit an extremely potent inhibitory activity on protein kinase C. The IC50 value was 32.9 nM.

Studies on lipoxygenase inhibitors. I. MY3-469 (3-methoxytropolone), a potent and selective inhibitor of 12-lipoxygenase, produced by Streptoverticillium hadanonense KY11449

Streptoverticillium hadanonense KY11449 was found to produce a 12-lipoxygenase inhibitor MY3-469. The compound was purified by chromatography on Diaion HP-10, charcoal, Sephadex LH-20 and crystallization. The chemical structure of MY3-469 was determined to be 3-methoxytropolone on the basis of its physico-chemical properties. The half maximal inhibitory concentration (IC50) of MY3-469 against bovine platelet 12-lipoxygenase was 1.8 X 10(-6)M. The compound did not inhibit bovine platelet cyclooxygenase at 10(-3)M and showed weak inhibition (IC50 2.8 X 10(-4)) against 5-lipoxygenase of rat basophilic leukemia cells. The results indicate that MY3-469 is a potent and selective inhibitor of 12-lipoxygenase.

K-4, a novel inhibitor of angiotensin I converting enzyme produced by Actinomadura spiculosospora

A novel inhibitor of angiotensin I converting enzyme (ACE), named K-4, was isolated from the culture broth of Actinomadura spiculosospora nov. sp. K-4. The K-4 was an oligopeptide containing L-phenylalanine with (R)-1-amino-2-(4-hydroxyphenyl)ethylphosphonic acid as the C-terminal residue. The compound proved to be a specific and reversible inhibitor of ACE with the inhibition constant (Ki) of 0.18 microM, and inhibited ACE non-competitively by use of hippuryl-L-histidyl-L-leucine (HHL) as a substrate. When administrated intravenously to rats, K-4 inhibited the pressor response to angiotensin I.

MY336-a, a novel beta-adrenergic receptor antagonist produced by Streptomyces gabonae

Streptomyces gabonae KY2234 was found to produce a new compound, MY336-a, which bound to beta-adrenergic receptor. The compound was isolated from the fermentation broth of KY2234. MY336-a showed a high affinity for the beta-receptor, labeled with [3H]dihydroalprenolol in the membrane fractions of rat heart (beta 1-adrenergic receptor) or lung (beta 2-adrenergic receptor), whereas the compound bound very weakly to alpha-adrenergic receptor, labeled with [3H]dihydroergokryptine in rat brain. the inhibition constants (Ki) of the compound were 0.73 and 0.14 microM for the beta-receptors of heart and lung, respectively. 5'-Guanylylimidodiphosphate (Gpp(NH)p) did not alter the affinity of the beta-receptors for MY336-a. In isolated guinea-pig atria, MY336-a produced an inhibition of the positive chronotropic and inotropic effects of isoproterenol. MY336-a also antagonized the relaxation of tone induced by isoproterenol in isolated guinea-pig trachea. No partial agonistic activity was detected in MY336-a in the isolated atria and trachea. In anaesthetized dogs, MY336-a (1 mg/kg, iv) exerted negative inotropic action (left ventricular dp/dt max, -32.6%).

K-26, a novel inhibitor of angiotensin I converting enzyme produced by an actinomycete K-26

A novel inhibitor of angiotensin I converting enzyme (ACE), designated K-26, was isolated from the broth filtrate of an actiomycete K-26. K-26 is a water soluble, acidic peptide composed of an equal mol of L-isoleucine, L-tyrosine and 1(R)-1-amino-2-(4-hydroxyphenyl)-ethylphosphonic acid. The IC50 of K-26 for ACE inhibition was 6.7 ng/ml when hippuryl-L-histidyl-L-leucine was used as a substrate of ACE. K-26 possesses hypotensive activity in vivo.

Biosynthesis of astromicin and related antibiotics. II. Biosynthetic studies with blocked mutants of Micromonospora olivasterospora

An inosamine-idiotrophic mutant, KY11559, which produced no astromicin unless scyllo-inosamine was added to the fermentation medium, was isolated from Micromonospora olivasterospora. Biotransformation studies were performed with resting cells of this mutant and compounds assumed to be precursors of 1,4-diaminocyclitol (fortamine). Scyllo-inosose, scyllo-inosamine and FU-10 were converted to astromicin. A number of mutants blocked in the biosynthesis of astromicin were developed from M. olivasterospora, and the intermediates accumulated by these mutants were isolated and identified. Twenty-five blocked mutants were classified into 10 groups, based on their complementation patterns by cosynthesis experiments. Further, utilizing these blocked mutants and the isolated compounds, biotransformation analyses were performed. The results showed that the amination at position 4 in fortamine occurred after formation of the pseudodisaccharide. Subsequently, the aminosugar and aminocyclitol moieties were aminated, methylated, dehydroxylated, epimerized and acylated to produce astromicin. Thus it was demonstrated that the astromicin biosynthetic pathway has a unique feature which is not found in the biosynthesis of other aminoglycoside antibiotics.

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.

Inhibition of calmodulin-dependent cyclic nucleotide phosphodiesterase by flunarizine, a calcium-entry blocker

It has been reported that flunarizine, classified as calcium entry-blockers, is a potent brain protective drug without any heart depressant effect, contrasting with other drugs in this group. This paper presents evidence that through a competitive antagonism against calmodulin, a major intracellular calcium receptor, flunarizine inhibits the calcium X calmodulin-activated phosphodiesterase activity of bovine brain, but not of heart, whereas other calcium-entry blockers and calmodulin antagonists inhibit to the same extent, the activation of the enzyme from the two sources. It could be suggested that some of pharmacological effects by flunarizine and its differences from other calcium-entry blockers may be explained by its interaction with calmodulin.

Sagamicin and the related aminoglycosides: fermentation and biosynthesis. III. Isolation and characterization of Micromonospora sagamiensis mutants blocked in gentamicin C1 pathway

Production of sagamicin and gentamicin C1 in Micromonospora sagamiensis was regulated by cobalt ion. In a parental strain, KY11510, cobalt ion stimulated gentamicin C1 production and suppressed sagamicin production. By ultraviolet light or N-methyl-N'-nitro-N-nitrosoguanidine treatment, six mutants blocked in gentamicin C1 biosynthesis were obtained from KY11510. These mutants were classified into two types. The first type, four mutants, produced no gentamicin C1 even when cobalt ion was added to the fermentation. The second type, two mutants, produced a small amount of gentamicin C1 when a high concentration of cobalt ion was added. Based on biotransformation experiments, these mutants appeared to be blocked at the 6'-C-methylation step in the biosynthesis of gentamicin C1. The mutants showed an increased production of sagamicin. In addition, cobalt ion stimulated sagamicin production in the mutants. The mechanism of cobalt regulation in the parent and the mutants is discussed.

Production of antibiotic SU-2 complex by a 2-deoxystreptamine idiotroph of Micromonospora sagamiensis

A 2-deoxystreptamine idiotrophic mutant of Micromonospora sagamiensis, KY 11509, was found to produce unknown antibacterial substances, which were named SU-2 complex. Each component, SU-1, SU-2 and SU-3 were isolated from a culture broth of KY 11509. Chromatographic data suggested that these components were new antibiotics. The antibiotics exhibited potent and broad spectrum of antibacterial activity. The amount of SU-1, SU-2 and SU-3 production reached their maximum level (197, 82 and 58 micrograms/liter, respectively) in 3 to 4 days. Addition of cobalt chloride markedly stimulated SU-1 production but suppressed SU-2 and SU-3 production. Isolation of a mutant possessing a higher productivity of SU-2 complex is also described.

Sagamicin and the related aminoglycosides: fermentation and biosynthesis. I. Biosynthetic studies with the blocked mutants of Micromonospora sagamiensis

The mutants blocked in the gentamicin C1 production were derived from a sagamicin producing strain of Micromonospora sagamiensis. The intermediates produced by these mutants were isolated and properly identified. Comparing the biotransformation activities in the resting cells of the mutants with those of a DOS idiotroph, KY 11525, the blocked steps in sagamicin and gentamicin biosynthesis were proposed in each mutant. Mutant KY 11564 was found to produce gentamicin C2a (C-6'-epimer of gentamicin C2) together with gentamicin C1a and sagamicin. KY 11525 transformed gentamicin C2a into C2 and C1, whereas KY 11564 lacked the activity. KY 11565 produced gentamicin X2 and antibiotic G-418, and lacked 6'-amino substitution activities. KY 11566 appeared to be partially blocked in 6'-N-methylation activities, and the major products were gentamicin C2a and C1a. From these results, sagamicin biosynthesis in M. sagamiensis is discussed.

Microbial production of essential amino acid with Corynebacterium glutamicum mutants

Amino acids produced by microbial process are generally L-forms. The stereospecificity of the amino acids produced by fermentation makes the process advantageous compared with synthetic process. Microorganisms employed in microbial process for amino acid production are divided into 4 classes; wild-type strain, auxotrophic mutant, regulatory mutant and auxotrophic regulatory mutant. Using such mutants of Corynebacterium glutamicum, all the essential amino acids but L-methionine are now being produced by "direct fermentation" from cheap carbon sources such as carbohydrate materials or acetic acid.