RESUMO
I first met Professor Omura, Distinguished Emeritus Professor, at The Kitasato Institute (Kitaken) when I was 28 years old. Since then, he has been my respectful supervisor as well as mentor. Looking back on those memories, I am deeply honored to write about the discovery and development of avermectin.
Assuntos
Academias e Institutos/história , Descoberta de Drogas/história , Ivermectina/análogos & derivados , Laboratórios/história , História do Século XX , História do Século XXI , HumanosRESUMO
The absolute stereostructure of luminamicin, an anaerobic antibiotic, has been determined by using conformational analysis via high-temperature molecular dynamics, NMR spectroscopy, and the modified Mosher method. It was found that luminamicin has the S, S, R, R, R, R, S, S, S, R, and S configurations at C2, C4, C7, C9, C10, C11, C12, C13, C16, C28, and C29, respectively. This configuration is the same as that found in nodusmicin, which has a chemical structure quite similar to luminamicin. The structure of luminamicin consists of three different rings, i.e., a decalin ring, a 10-membered macrolactone ring, and a 14-membered macrolactone ring. The resulting three-dimensional structure of luminamicin shows an interesting feature in that the maleic anhydride functionality in conjugation with the enol ether group of the 14-membered macrolactone is nearly perpendicular to the plane of the other two rings.
Assuntos
Antibacterianos/química , Bactérias Anaeróbias/química , Lactonas/química , Espectroscopia de Ressonância Magnética , Conformação MolecularRESUMO
The taxonomic position was determined for a soil actinomycete, isolate KM-4927(T), that produced the antibiotic hitachimycin. The strain was assigned to the genus Streptomyces on the basis of 16S rDNA analysis, where it formed a separate clade. The strain is characterized by grey aerial cell mass, spiral spore chains and a rugose spore surface, menaquinones of the MK-9(H(4), H(2), H(6)) types and cell-wall chemotype I. DNA-DNA reassociation with 21 phylogenetically neighbouring Streptomyces type strains showing similar morphological characteristics to strain KM-4927(T) indicated that this isolate is only moderately related to other Streptomyces species. On the basis of genomic and physiological properties, the novel species Streptomyces scabrisporus sp. nov. is proposed; the type strain is strain KM-4927(T) (=JCM 11712(T)=NRRL B-24202(T)).
Assuntos
Streptomyces/classificação , DNA Bacteriano/genética , DNA Ribossômico/genética , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Fenótipo , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Microbiologia do Solo , Esporos Bacterianos/ultraestrutura , Streptomyces/genética , Streptomyces/isolamento & purificação , Streptomyces/fisiologiaRESUMO
A novel actinomycete strain was isolated from a soil sample collected in Japan by using gellan gum as a solidifying agent. Spore-chains from the short sporophores were straight and each had more than 20 spores per chain. Spores possessed no motility. Cell-wall peptidoglycan contained meso-diaminopimelic acid, glycine, alanine and glutamic acid; whole-cell hydrolysates contained arabinose, galactose and xylose. The acyl type of the peptidoglycan was glycolyl. The predominant menaquinones were MK-10(H(4)) and MK-10(H(6)); MK-10(H(8)) was a minor component. Mycolic acids were not detected. The diagostic phospholipid was phosphatidylethanolamine. Cellular fatty acids included heptadecenoic (C(17 : 1)), 14-methylpentadecanoic (i-C(16 : 0)) and octadecenoic (C(18 : 1)) acids. The G+C content of the DNA was 70 mol%. On the basis of morphogical and chemotaxonomic properties and phylogenetic analysis based on 16S rDNA sequence data, it is proposed that this strain should be classified in a novel genus and species, Longispora albida gen. nov., sp. nov., in the family MICROMONOSPORACEAE: The type strain is K97-0003(T) (=NRRL B-24201(T)=JCM 11711(T)).
Assuntos
Micromonosporaceae/classificação , Composição de Bases , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/genética , Ácidos Graxos/análise , Japão , Micromonosporaceae/genética , Micromonosporaceae/isolamento & purificação , Micromonosporaceae/metabolismo , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Peptidoglicano/química , Fenótipo , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Microbiologia do SoloRESUMO
We propose the establishment of a new species, Streptomyces avermectinius, based on characterization of strain MA-4680(T) and morphological and phylogenetic comparisons with closely related members of the genus Streptomyces. The 16S rDNA sequence was obtained from this strain and used to place it among Streptomyces species using the variable alpha region and the nearly complete 16S rDNA sequence. Four Streptomyces species were selected as related species from phenotypic data, three species from phylogenetic databases on alpha region sequences and two species from phylogenetic data using nearly complete 16S rDNA sequences. Analysis of DNA-DNA hybridization tests distinguished strain MA-4680(T) from these eight Streptomyces species. The type strain is strain MA-4680(T) (= ATCC 31267(T) = NRRL 8165(T)).
