| iron, a novel outer membrane siderophore receptor characteristic of salmonella enterica. | speciation in enterobacteria involved horizontal gene transfer. therefore, analysis of genes acquired by horizontal transfer that are present in one species but not its close relatives is expected to give insights into how new bacterial species were formed. in this study we characterize iron, a gene located downstream of the irobc operon in the iroa locus of salmonella enterica serotype typhi. like irobc, the iron gene is present in all phylogenetic lineages of s. enterica but is absent from clo ... | 1998 | 9515912 |
| tonb-dependent transporters and their occurrence in cyanobacteria. | different iron transport systems evolved in gram-negative bacteria during evolution. most of the transport systems depend on outer membrane localized tonb-dependent transporters (tbdts), a periplasma-facing tonb protein and a plasma membrane localized machinery (exbbd). so far, iron chelators (siderophores), oligosaccharides and polypeptides have been identified as substrates of tbdts. for iron transport, three uptake systems are defined: the lactoferrin/transferrin binding proteins, the porphyr ... | 2009 | 19821963 |
| insights into an unusual nonribosomal peptide synthetase biosynthesis: identification and characterization of the ge81112 biosynthetic gene cluster. | the ge81112 tetrapeptides (1-3) represent a structurally unique class of antibiotics, acting as specific inhibitors of prokaryotic protein synthesis. here we report the cloning and sequencing of the ge81112 biosynthetic gene cluster from streptomyces sp. l-49973 and the development of a genetic manipulation system for streptomyces sp. l-49973. the biosynthetic gene cluster for the tetrapeptide antibiotic ge81112 (geta-n) was identified within a 61.7-kb region comprising 29 open reading frames (o ... | 2010 | 20710026 |
| 2-(3'-indolyl)-n-arylthiazole-4-carboxamides: synthesis and evaluation of antibacterial and anticancer activities. | a new series of 2-(3'-indolyl)-n-arylthiazole-4-carboxamides 17a-p has been designed and synthesized. initial reaction of readily available thioamides 15 with bromopyruvic acid under refluxing conditions produced different thiazole carboxylic acids 16 which upon coupling with arylamines by using edci·hcl and hobt afforded diverse arylthiazole-4-carboxamides 17a-p in 78-87% yields. antibacterial activity evaluation against gram-positive and gram-negative bacterial strains led to compounds 17i-k a ... | 2015 | 26298501 |
| explorations of catalytic domains in non-ribosomal peptide synthetase enzymology. | many pharmaceuticals on the market today belong to a large class of natural products called nonribosomal peptides (nrps). originating from bacteria and fungi, these peptide-based natural products consist not only of the 20 canonical l-amino acids, but also non-proteinogenic amino acids, heterocyclic rings, sugars, and fatty acids, generating tremendous chemical diversity. as a result, these secondary metabolites exhibit a broad array of bioactivity, ranging from antimicrobial to anticancer. the ... | 2012 | 22802156 |
| differences between the rhizosphere microbiome of beta vulgaris ssp. maritima-ancestor of all beet crops-and modern sugar beets. | the structure and function of the plant microbiome is driven by plant species and prevailing environmental conditions. effectuated by breeding efforts, modern crops diverge genetically and phenotypically from their wild relatives but little is known about consequences for the associated microbiota. therefore, we studied bacterial rhizosphere communities associated with the wild beet b. vulgaris ssp. maritima grown in their natural habitat soil from coastal drift lines (cs) and modern sugar beets ... | 2014 | 25206350 |
| total synthesis and biological evaluation of tubulysin u, tubulysin v, and their analogues. | a stereoselective total synthesis of the cytotoxic natural products tubulysin u, tubulysin v, and its unnatural epimer epi-tubulysin v, is reported. simplified analogues containing n,n-dimethyl-d-alanine as a replacement for the n-terminal n-me-pipecolinic acid residue of the tubulysins are also disclosed. biological evaluation of these natural products and analogues provided key information with regard to structural and stereochemical requirements for antiproliferative activity and tubulin poly ... | 2009 | 19102699 |
| functional promiscuity of homologues of the bacterial arsa atpases. | the arsa atpase of e. coli plays an essential role in arsenic detoxification. published evidence implicates arsa in the energization of as(iii) efflux via the formation of an oxyanion-translocating complex with arsb. in addition, eukaryotic arsa homologues have several recognized functions unrelated to arsenic resistance. by aligning arsa homologues, constructing phylogenetic trees, examining arsa encoding operons, and estimating the probable coevolution of these homologues with putative transpo ... | 2010 | 20981284 |
| fatty acid-related phylogeny of myxobacteria as an approach to discover polyunsaturated omega-3/6 fatty acids. | in an analysis of 47 aerobic myxobacterial strains, representing 19 genera in suborders cystobacterineae, nannocystineae, sorangiineae, and a novel isolate, "aetherobacter" sbsr008, an enormously diverse array of fatty acids (fas) was found. the distribution of straight-chain fatty acids (scfas) and branched-chain fatty acids (bcfas) supports the reported clustering of strains in the phylogenetic tree based on 16s rrna genes. this finding additionally allows the prediction and assignment of the ... | 2011 | 21317327 |
| a framework for classification of prokaryotic protein kinases. | overwhelming majority of the serine/threonine protein kinases identified by gleaning archaeal and eubacterial genomes could not be classified into any of the well known hanks and hunter subfamilies of protein kinases. this is owing to the development of hanks and hunter classification scheme based on eukaryotic protein kinases which are highly divergent from their prokaryotic homologues. a large dataset of prokaryotic serine/threonine protein kinases recognized from genomes of prokaryotes have b ... | 2010 | 20520783 |
| biological evaluation of tubulysin a: a potential anticancer and antiangiogenic natural product. | tubulysin a (tuba) is a natural product isolated from a strain of myxobacteria that has been shown to depolymerize microtubules and induce mitotic arrest. the potential of tuba as an anticancer and antiangiogenic agent is explored in the present study. tuba shows potent antiproliferative activity in a panel of human cancer cell lines irrespective of their multidrug resistance properties. it induces apoptosis in cancer cells but not in normal cells and shows significant potential antiangiogenic p ... | 2006 | 16489930 |
| characterization and description of anaeromyxobacter dehalogenans gen. nov., sp. nov., an aryl-halorespiring facultative anaerobic myxobacterium. | five strains were isolated which form a physiologically and phylogenetically coherent group of chlororespiring microorganisms and represent the first taxon in the myxobacteria capable of anaerobic growth. the strains were enriched and isolated from various soils and sediments based on their ability to grow using acetate as an electron donor and 2-chlorophenol (2-cph) as an electron acceptor. they are slender gram-negative rods with a bright red pigmentation that exhibit gliding motility and form ... | 2002 | 11823233 |
| role of molybdate and other transition metals in the accumulation of protochelin by azotobacter vinelandii. | both molybdate and iron are metals that are required by the obligately aerobic organism azotobacter vinelandii to survive in the nutrient-limited conditions of its natural soil environment. previous studies have shown that a high concentration of molybdate (1 mm) affects the formation of a. vinelandii siderophores such that the tricatecholate protochelin is formed to the exclusion of the other catecholate siderophores, azotochelin and aminochelin. it has been shown previously that molybdate comb ... | 2000 | 10742245 |
| salmonella typhimurium iron and fepa proteins mediate uptake of enterobactin but differ in their specificity for other siderophores. | salmonella typhimurium possesses two outer membrane receptor proteins, iron and fepa, which have been implicated in the uptake of enterobactin. to determine whether both receptors have identical substrate specificities, fepa and iron mutants and a double mutant were characterized. while both receptors transported enterobactin, the uptake of corynebactin and myxochelin c was selectively mediated by iron and fepa, respectively. | 1999 | 10348879 |
| stereoselective access to tubuphenylalanine and tubuvaline: improved mn-mediated radical additions and assembly of a tubulysin tetrapeptide analog. | synthesis of tubuphenylalanine and tubuvaline (tuv), α-substituted γ-amino acid building blocks for tubulysin family of antimitotic compounds, has been improved using a radical addition reaction in the presence of unprotected hydroxyl functionality. the key carbon-carbon bond construction entails stereoselective mn-mediated photolytic additions of alkyl iodides to the c=n bond of chiral n-acylhydrazones, and generates the chiral amines in high yield with complete stereocontrol. reductive n-n bon ... | 2016 | 26883395 |
| biosynthetic modularity rules in the bisintercalator family of antitumor compounds. | diverse actinomycetes produce a family of structurally and biosynthetically related non-ribosomal peptide compounds which belong to the chromodepsipeptide family. these compounds act as bisintercalators into the dna helix. they give rise to antitumor, antiparasitic, antibacterial and antiviral bioactivities. these compounds show a high degree of conserved modularity (chromophores, number and type of amino acids). this modularity and their high sequence similarities at the genetic level imply a c ... | 2014 | 24821625 |
| pretubulysin: from hypothetical biosynthetic intermediate to potential lead in tumor therapy. | pretubulysin is a natural product that is found in strains of myxobacteria in only minute amounts. it represents the first enzyme-free intermediate in the biosynthesis of tubulysins and undergoes post-assembly acylation and oxidation reactions. pretubulysin inhibits the growth of cultured mammalian cells, as do tubulysins, which are already in advanced preclinical development as anticancer and antiangiogenic agents. the mechanism of action of this highly potent compound class involves the depoly ... | 2012 | 22616003 |
| isolation and identification of myxobacteria from saline-alkaline soils in xinjiang, china. | fifty-eight terrestrial and salt-tolerant myxobacteria were isolated from the saline-alkaline soils collected from xinjiang, china. based on the morphologies and the 16s rrna gene sequences, these isolates were assigned into 6 genera, myxococcus, cystobacter, corallococcus, sorangium, nannocystis and polyangium. all the strains grew better with 1% nacl than without nacl. some myxococcus strains were able to grow at 2% nacl concentration, suggesting that these strains may be particular type of te ... | 2013 | 23936436 |