oligomycins and ossamycin

Topics: Aminoglycosides; Animals; Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Aurovertins; Energy Transfer; Macrolides; Mitochondria; Oligomycins; Peptides; Peptides, Cyclic; Venturicidins

[figure: see text] We describe a semi-synthetic deglycosylated derivative of apoptolidin that retains considerable activity against the mitochondrial ATPase but has greatly reduced cellular cytotoxicity. We also demonstrate that a related antifungal natural product, cytovaricin, inhibits the same molecular target. Structural comparison of these macrolides provides insights into their conserved features that are presumably important for biological activity and identifies promising avenues at the interface of organic synthesis and biosynthesis for the generation of new selective cytotoxic agents.

Topics: Anti-Bacterial Agents; Antibiotics, Antineoplastic; Antifungal Agents; Bacteria; Biological Products; Enzyme Inhibitors; Macrolides; Molecular Structure; Oligomycins; Proton-Translocating ATPases; Structure-Activity Relationship; Yeasts

Recently, a family of polyketide inhibitors of F(0)F(1)-ATPase, including apoptolidin, ossamycin, and oligomycin, were shown to be among the top 0.1% most cell line selective cytotoxic agents of 37, 000 molecules tested against the 60 human cancer cell lines of the National Cancer Institute. Many cancer cells maintain a high level of anaerobic carbon metabolism even in the presence of oxygen, a phenomenon that is historically known as the Warburg effect. A mechanism-based strategy to sensitize such cells to this class of potent small molecule cytotoxic agents is presented. These natural products inhibit oxidative phosphorylation by targeting the mitochondrial F(0)F(1) ATP synthase. Evaluation of gene expression profiles in a panel of leukemias revealed a strong correlation between the expression level of the gene encoding subunit 6 of the mitochondrial F(0)F(1) ATP synthase (known to be the binding site of members of this class of macrolides) and their sensitivity to these natural products. Within the same set of leukemia cell lines, comparably strong drug-gene correlations were also observed for the genes encoding two key enzymes involved in central carbon metabolism, pyruvate kinase, and aspartate aminotransferase. We propose a simple model in which the mitochondrial apoptotic pathway is activated in response to a shift in balance between aerobic and anaerobic ATP biosynthesis. Inhibitors of both lactate formation and carbon flux through the Embden-Meyerhof pathway significantly sensitized apoptolidin-resistant tumors to this drug. Nine different cell lines derived from human leukemias and melanomas, and colon, renal, central nervous system, and ovarian tumors are also sensitized to killing by apoptolidin.

Topics: Anti-Bacterial Agents; Antibiotics, Antineoplastic; DNA-Binding Proteins; HT29 Cells; Humans; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Macrolides; Molecular Structure; Nuclear Proteins; Oligomycins; Proton-Translocating ATPases; Transcription Factors; Tumor Cells, Cultured

Petite deletion mapping helped to generate a fine-structure genetic map of the Oli-2 region of the mitochondrial genome of Saccharomyces cerevisiae. Here we report the DNA sequence analysis of the Oli-2 region from two drug-resistant alleles (Olir2-76 and Ossr1-92) which are located in the gene for subunit-6 of mitochondrial ATPase, in agreement with their genetic locations on the mitochondrial genome. An analysis of the corresponding amino-acid substitutions is also presented in the context of protein-antibiotic interactions.

Topics: Adenosine Triphosphatases; Amino Acid Sequence; Aminoglycosides; Anti-Bacterial Agents; Base Sequence; Binding Sites; Cloning, Molecular; DNA, Fungal; DNA, Mitochondrial; Drug Resistance; Macrolides; Membrane Proteins; Molecular Sequence Data; Mutation; Oligomycins; Oxidative Phosphorylation; Protein Conformation; Saccharomyces cerevisiae

The antibiotics venturicidin, oligomycin and ossamycin were investigated as potential inhibitors of the Escherichia coli H+-ATPase. It was found that venturicidin strongly inhibited ATP-driven proton transport and ATP hydrolysis, while oligomycin weakly inhibited these functions. Inhibition of the H+-ATPase by venturicidin and oligomycin was correlated with inhibition of F0-mediate proton transport. Both inhibitors were found to interfere with the covalent reaction between dicyclohexyl[14C]carbodiimide and the F0 subunit c (uncE protein). Ossamycin had no direct inhibitory effect on E. coli F0 or F1; rather, it was found to uncouple ATP hydrolysis from proton transport.

Topics: Adenosine Triphosphate; Aminoglycosides; Anti-Bacterial Agents; Biological Transport, Active; Escherichia coli; Hydrogen-Ion Concentration; Lactones; Macrolides; Oligomycins; Proton-Translocating ATPases; Uncoupling Agents; Venturicidins

Rat testis mitochondrial ATPase was not inhibited by oligomycin at pH 7.5. It was inhibited only at higher alkaline pH's, and showed a lower sensitivity both to oligomycin and N,N'-dicyclohexylcarbodiimide and a higher one to efrapeptin. In submitochondrial particles, testis ATPase was only slightly inhibited by oligomycin, ossamycin, and efrapeptin. The possibility of a loose binding of F1 to the membrane was supported by its recovery from the supernatant of the submitochondrial particles. Furthermore, by electron microscopy, after hypoosmotic shock and negative staining of the mitochondrial preparations, most of the inner mitochondrial membranes showed only a few "knobs" or none at all. The capacity of the testis mitochondrial preparation to produce ATP was tested and compared to that from liver. ATP synthetase/ATPase activity ratio was 30/1 in liver mitochondria, whereas in the testis it was 3/1. In spite of this large difference, at least part of the testis ATPase must be firmly bound to the membrane, since it is able to form ATP. The rest seems to be loosely bound and its functional significance is still unknown.

Topics: Adenosine Triphosphatases; Aminoglycosides; Animals; Anti-Bacterial Agents; Dicyclohexylcarbodiimide; In Vitro Techniques; Intracellular Membranes; Macrolides; Magnesium; Male; Microscopy, Electron; Mitochondria; Mitochondria, Liver; Oligomycins; Peptides; Protein Binding; Rats; Rats, Inbred Strains; Submitochondrial Particles; Testis

The mitochondrial ATPase from oligomycin-resistant mutants which map on different regions of an extrachromosomal DNA (01 and 011 class mutants) showed an increased resistance to oligomycin and venturicidin when assayed in vitro as compared to the sensitive strains. The resistance to oligomycin of the isolated mitochondrial ATPase from 01 class mutants was higher than that of the 011 class mutants. Cross resistance of the oligomycin-resistant mutants to the antibiotics peliomycin and ossamycin, which also inhibit phosphoryl transfer reactions in mitochondria (Walter et al., 1967), was observed, 01 mutants being more resistant to ossamycin than 011 class mutants. At the concentrations of peliomycin studied, no difference in sensitivity among both groups of oligomycin-resistant mutants could be detected. Mitochondrial respiration and isolated mitochondrial ATPase activity are sensitive to venturicidin, suggesting that the previously observed (Brunner et al., 1977) in vivo venturicidin resistance of K. lactis is probably due to an impairment of the influx of the drug at the level of the plasma membrane.

Topics: Adenosine Triphosphatases; Aminoglycosides; Anti-Bacterial Agents; DNA, Fungal; DNA, Mitochondrial; Drug Resistance, Microbial; Macrolides; Mitochondria; Oligomycins; Streptomyces; Venturicidins; Yeasts

With a view towards identifying new ATPase loci on the mitochondrial genome a large number of oligomycin-, ossamycin- and venturicidin-resistant mutants were isolated after MnCl2 mutagenesis. The mutants were subjected to mass-screens which divided them into different cross-resistance phenotype-classes and also distinguished the common OLI1 mutations from the mutations at all other loci. Allelism tests between examples of the different classes of phenotype indicated that the majority of mutations in the population mapped at the previously known loci OLI1, OLI2, OLI3, and OLI4. Mutations conferring specific ossamycin resistance defined two new loci, namely OSS1 and OSS2 which are linked to the OLI2 and OLI1 loci respectively. A few rare mutations comprise a new locus OLI5 which is linked to the OLI1 locus (12.6% total recombination). In conclusion we can now say that that there are two unlinked segments of the mitochondrial genome, each of which is composed of several distinct, genetically-linked loci. One segment contains the OLI1, OLI3, OLI5 and OSS2 loci and the other the OLI2, OLI4 and OSS1 loci. The phenotypically-distinguishable mutations described herein should facilitate fine-structure mapping of these two segments.

Topics: Adenosine Triphosphatases; Anti-Bacterial Agents; DNA, Mitochondrial; Drug Resistance, Microbial; Macrolides; Mitochondria; Oligomycins; Oxidative Phosphorylation; Saccharomyces cerevisiae; Uncoupling Agents; Venturicidins