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Pikromycin
Pikromycin was studied by Brokmann and Hekel in 1951 and was the first antibiotic macrolide to be isolated. Pikromycin is synthesized through a type I polyketide synthase system in ''Streptomyces venezuelae'', a species of Gram-positive bacterium in the genus ''Streptomyces''. Pikromycin is derived from narbonolide, a 14-membered ring macrolide. Along with the narbonolide backbone, pikromycin includes a desosamine sugar and a hydroxyl group. Although Pikromycin is not a clinically useful antibiotic, it can be used as a raw material to synthesize antibiotic ketolide compounds such as Erythromycin, erythromycins and new epothilones. __TOC__ Biosynthesis The pikromycin polyketide synthase of ''Streptomyces venezuelae'' contains four polypeptides: PikAI, PikAII, PikAIII, and PikAIV. These polypeptides contain a loading module, six extension molecules, and a thioesterase domain that terminated the biosynthetic procedure. Recently electron cryo-microscopy have been used to determine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pikromycin2
Pikromycin was studied by Brokmann and Hekel in 1951 and was the first antibiotic macrolide to be isolated. Pikromycin is synthesized through a type I polyketide synthase system in '' Streptomyces venezuelae'', a species of Gram-positive bacterium in the genus ''Streptomyces''. Pikromycin is derived from narbonolide, a 14-membered ring macrolide. Along with the narbonolide backbone, pikromycin includes a desosamine sugar and a hydroxyl group. Although Pikromycin is not a clinically useful antibiotic, it can be used as a raw material to synthesize antibiotic ketolide compounds such as erythromycins and new epothilones. __TOC__ Biosynthesis The pikromycin polyketide synthase of ''Streptomyces venezuelae'' contains four polypeptides: PikAI, PikAII, PikAIII, and PikAIV. These polypeptides contain a loading module, six extension molecules, and a thioesterase domain that terminated the biosynthetic procedure. Recently electron cryo-microscopy have been used to determine sub-nanom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrolide
Macrolides are a class of mostly natural products with a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. Macrolides belong to the polyketide class of natural products. Some macrolides have antibiotic or antifungal activity and are used as pharmaceutical drugs. Rapamycin is also a macrolide and was originally developed as an antifungal, but has since been used as an immunosuppressant drug and is being investigated as a potential longevity therapeutic. Macrolides are a diverse group with many members of very different properties: * Macrolides with 14-, 15-, or 16-membered rings and two attached sugar molecules are antibiotics that bind to bacterial ribosomes, the key representative being erythromycin. The term "macrolide antibiotics" tend to refer to just this class. * Some macrolides with very large (20+ membered) rings are immunosuppresants, the prototypical one being rapamycin. * Some 23-membered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyketide Synthase
Polyketide synthases (PKSs) are a family of multi- domain enzymes or enzyme complexes that produce polyketides, a large class of secondary metabolites, in bacteria, fungi, plants, and a few animal lineages. The biosyntheses of polyketides share striking similarities with fatty acid biosynthesis. The PKS genes for a certain polyketide are usually organized in one operon or in gene clusters. Type I and type II PKSs form either large modular protein complexes or dissociable molecular assemblies; type III PKSs exist as smaller homodimeric proteins. Classification PKSs can be classified into three types: * Type I PKSs are large, complex protein structures with multiple modules which in turn consist of several domains that are usually covalently connected to each other and fulfill different catalytic steps. The minimal composition of a type I PKS module consists of an acyltransferase (AT) domain, which is responsible for choosing the building block to be used, a keto synthase (KS) do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptomyces Venezuelae
''Streptomyces venezuelae'' is a species of soil-dwelling Gram-positive bacterium of the genus ''Streptomyces''. ''S. venezuelae'' is filamentous. In its spore-bearing stage, hyphae perfuse both above ground as aerial hyphae and in the soil substrate. Chloramphenicol, the first antibiotic to be manufactured synthetically on a large scale, was originally derived from ''S. venezuelae''. Other secondary metabolites produced by ''S. venezuelae'' include jadomycin and pikromycin Pikromycin was studied by Brokmann and Hekel in 1951 and was the first antibiotic macrolide to be isolated. Pikromycin is synthesized through a type I polyketide synthase system in ''Streptomyces venezuelae'', a species of Gram-positive bacterium .... See also * Chloramphenicol phosphotransferase-like protein family References Further reading * External linksType strain of ''Streptomyces venezuelae'' at Bac''Dive'' – the Bacterial Diversity Metadatabase venezuelae Bacteria desc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gram-positive
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is used by microbiologists to place bacteria into two main categories, gram-positive (+) and gram-negative bacteria, gram-negative (−). Gram-positive bacteria have a thick layer of peptidoglycan within the cell wall, and gram-negative bacteria have a thin layer of peptidoglycan. Gram-positive bacteria retain the crystal violet stain used in the test, resulting in a purple color when observed through an optical microscope. The thick layer of peptidoglycan in the bacterial cell wall retains the Stain (biology), stain after it has been fixed in place by iodine. During the decolorization step, the decolorizer removes crystal violet from all other cells. Conversely, gram-negative bacteria cannot retain the violet stain after the decolorization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptomyces
''Streptomyces'', from στρεπτός (''streptós''), meaning "twisted", and μύκης (''múkés''), meaning "fungus", is the largest genus of Actinomycetota, and the type genus of the family Streptomycetaceae. Over 700 species of ''Streptomyces'' bacteria have been described. As with the other Actinomycetota, streptomycetes are gram-positive, and have very large genomes with high GC content. Found predominantly in soil and decaying vegetation, most streptomycetes produce spores, and are noted for their distinct "earthy" odor that results from production of a volatile metabolite, geosmin. Different strains of the same species may colonize very diverse environments. Streptomycetes are characterised by a complex secondary metabolism. Between 5-23% (average: 12%) of the protein-coding genes of each ''Streptomyces'' species are implicated in secondary metabolism. Streptomycetes produce over two-thirds of the clinically useful antibiotics of natural origin (e.g., neomy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erythromycin
Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used during pregnancy to prevent Group B streptococcal infection in the newborn, and to improve delayed stomach emptying. It can be given intravenously and by mouth. An eye ointment is routinely recommended after delivery to prevent eye infections in the newborn. Common side effects include abdominal cramps, vomiting, and diarrhea. More serious side effects may include ''Clostridioides difficile'' colitis, liver problems, prolonged QT, and allergic reactions. It is generally safe in those who are allergic to penicillin. Erythromycin also appears to be safe to use during pregnancy. While generally regarded as safe during breastfeeding, its use by the mother during the first two weeks of life may increase the risk of pyloric stenosis in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epothilone
Epothilones are a class of potential cancer drugs. Like taxanes, they prevent cancer cells from dividing by interfering with tubulin, but in early trials, epothilones have better efficacy and milder adverse effects than taxanes. Epothilones were originally identified as metabolites produced by the soil-dwelling myxobacterium ''Sorangium cellulosum''. , epothilones A to F have been identified and characterized. Early studies in cancer cell lines and human cancer patients indicate superior efficacy to the taxanes. Their mechanism of action is similar, but their chemical structure is simpler. Due to their better water solubility, cremophors (solubilizing agents used for paclitaxel which can affect cardiac function and cause severe hypersensitivity) are not needed. Endotoxin-like properties known from paclitaxel, like activation of macrophages synthesizing inflammatory cytokines and nitric oxide, are not observed for epothilone B. History The structure of epothilone A was determin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thioesterase
In biochemistry, thioesterases are enzymes which belong to the esterase family. Esterases, in turn, are one type of the several hydrolases known. Thioesterases exhibit esterase activity (splitting of an ester into an acid and an alcohol, in the presence of water) specifically at a thiol group (). Thioesterases or thiolester hydrolases are identified as members of EC 3.1.2. Family The thioesterase activity is performed by members of the acyl-CoA thioesterase (ACOT) family. The regulatory role of ACOT in fatty acid metabolism depends on their substrate specificity, tissue expression and subcellular localization. For example, deactivation of fatty acids at the ER may traffic fatty acids away from pathways associated with the ER membrane, such as glycerolipid biosynthesis. Two structurally different ACOT types lead to a similar enzymatic activity in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acyl Carrier Protein
The acyl carrier protein (ACP) is a cofactor of both fatty acid and polyketide biosynthesis machinery. It is one of the most abundant proteins in cells of ''E. coli.'' In both cases, the growing chain is bound to the ACP via a thioester derived from the distal thiol of a 4'-phosphopantetheine moiety. Structure The ACPs are small negatively charged α-helical bundle proteins with a high degree of structural and amino acid similarity. The structures of a number of acyl carrier proteins have been solved using various NMR and crystallography techniques. The ACPs are related in structure and mechanism to the peptidyl carrier proteins (PCP) from nonribosomal peptide synthases. Biosynthesis Subsequent to the expression of the inactive ''apo'' ACP, the 4'-phosphopantetheine moiety is attached to a serine residue. This coupling is mediated by acyl carrier protein synthase (ACPS), a 4'-phosphopantetheinyl transferase. 4'-Phosphopantetheine is a prosthetic group of several acyl carrier pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
