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Hatano K,
Nishii T,
Kasai H,
( 2003 ) Taxonomic re-evaluation of whorl-forming Streptomyces (formerly Streptoverticillium) species by using phenotypes, DNA-DNA hybridization and sequences of gyrB, and proposal of Streptomyces luteireticuli (ex Katoh and Arai 1957) corrig., sp. nov., nom. rev. PMID : 13130042 : DOI : 10.1099/ijs.0.02238-0 Abstract >>
The taxonomic status of 64 strains of whorl-forming Streptomyces (formerly Streptoverticillium) species was re-evaluated and strains were reclassified on the basis of their phenotypes, DNA-DNA hybridization data and partial sequences of gyrB, the structural gene of the B subunit of DNA gyrase. These strains, which consisted of 46 species and eight subspecies with validly published names and 13 species whose names have not been validly published [including 10 strains examined by the International Streptomyces Project (ISP)], were divided into two groups, namely typical and atypical whorl-forming Streptomyces species, based on their phenotypes and gyrB gene sequences. The typical whorl-forming species (59 strains) were divided into six major clusters of three or more species, seven minor clusters of two species and five single-member clusters, based on the threshold value of 97 % gyrB sequence similarity. Major clusters were typified by Streptomyces abikoensis, Streptomyces cinnamoneus, Streptomyces distallicus, Streptomyces griseocarneus, Streptomyces hiroshimensis and Streptomyces netropsis. Phenotypically, members of each cluster resembled each other closely except for the S. distallicus cluster, which was divided phenotypically into the S. distallicus and Streptomyces stramineus subclusters, and the S. netropsis cluster, which was divided into the S. netropsis and Streptomyces eurocidicus subclusters. Strains in each minor cluster closely resembled each other phenotypically. DNA-DNA relatedness between the representative species and others in each major cluster and/or subcluster, and between strains in the minor clusters, was >70 %, indicating that the major clusters and/or subclusters and the minor clusters each comprise a single species. It was concluded that 59 strains of typical whorl-forming Streptomyces species consisted of the following 18 species, including subjective synonym(s): S. abikoensis, Streptomyces ardus, Streptomyces blastmyceticus, S. cinnamoneus, S. eurocidicus, S. griseocarneus, S. hiroshimensis, Streptomyces lilacinus, 'Streptomyces luteoreticuli', Streptomyces luteosporeus, Streptomyces mashuensis, Streptomyces mobaraensis, Streptomyces morookaense, S. netropsis, Streptomyces orinoci, S. stramineus, Streptomyces thioluteus and Streptomyces viridiflavus.
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2. |
Yu F,
Li M,
Xu C,
Sun B,
Zhou H,
Wang Z,
Xu Q,
Xie M,
Zuo G,
Huang P,
Guo H,
Wang Q,
He J,
( 2016 ) Crystal structure and enantioselectivity of terpene cyclization in SAM-dependent methyltransferase TleD. PMID : 27613858 : DOI : 10.1042/BCJ20160695 Abstract >>
TleD is a SAM (S-adenosyl-l-methionine)-dependent methyltransferase and acts as one of the key enzymes in the teleocidin B biosynthesis pathway. Besides methyl transferring, TleD also rearranges the geranyl and indole moieties of the precursor to form a six-membered ring. Moreover, it does not show homologies with any known terpenoid cyclases. In order to elucidate how such a remarkable reaction could be achieved, we determined the complex crystal structures of TleD and the cofactor analogue S-adenosyl-l-homocysteine with or without the substrate teleocidin A1. A domain-swapped pattern via an additional N-terminal �\-helix is observed in TleD hexamers. Structural comparison and alignment shows that this additional N-terminal �\-helix is the common feature of SAM methyltransferase-like cyclases TleD and SpnF. The residue Tyr21 anchors the additional N-terminal �\-helix to a 'core SAM-MT fold' and is a key residue for catalytic activity. Molecular dynamics simulation results suggest that the dihedral angle C23-C24-C25-C26 of teleocidin A1 is preferred to 60-90�X in the TleD and substrate complex structure, which tend to adopt a Re-face stereocenter at C25 position after reaction and is according to in vitro enzyme reaction experiments. Our results also demonstrate that methyl transfer can be a new chemical strategy for carbocation formation in the terpene cyclization, which is the key initial step.
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3. |
Mori T,
Zhang L,
Awakawa T,
Hoshino S,
Okada M,
Morita H,
Abe I,
( 2016 ) Manipulation of prenylation reactions by structure-based engineering of bacterial indolactam prenyltransferases. PMID : 26952246 : DOI : 10.1038/ncomms10849 PMC : PMC4786772 Abstract >>
Prenylation reactions play crucial roles in controlling the activities of biomolecules. Bacterial prenyltransferases, TleC from Streptomyces blastmyceticus and MpnD from Marinactinospora thermotolerans, catalyse the 'reverse' prenylation of (-)-indolactam V at the C-7 position of the indole ring with geranyl pyrophosphate or dimethylallyl pyrophosphate, to produce lyngbyatoxin or pendolmycin, respectively. Using in vitro analyses, here we show that both TleC and MpnD exhibit relaxed substrate specificities and accept various chain lengths (C5-C25) of the prenyl donors. Comparisons of the crystal structures and their ternary complexes with (-)-indolactam V and dimethylallyl S-thiophosphate revealed the intimate structural details of the enzyme-catalysed 'reverse' prenylation reactions and identified the active-site residues governing the selection of the substrates. Furthermore, structure-based enzyme engineering successfully altered the preference for the prenyl chain length of the substrates, as well as the regio- and stereo-selectivities of the prenylation reactions, to produce a series of unnatural novel indolactams.
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4. |
Awakawa T,
Zhang L,
Wakimoto T,
Hoshino S,
Mori T,
Ito T,
Ishikawa J,
Tanner ME,
Abe I,
( 2014 ) A methyltransferase initiates terpene cyclization in teleocidin B biosynthesis. PMID : 24992358 : DOI : 10.1021/ja505224r Abstract >>
Teleocidin B is an indole terpenoid isolated from Streptomyces. Due to its unique chemical structure and ability to activate protein kinase C, it has attracted interest in the areas of organic chemistry and cell biology. Here, we report the identification of genes encoding enzymes for teleocidin B biosynthesis, including nonribosomal peptide synthetase (tleA), P-450 monooxygenase (tleB), prenyltransferase (tleC), and methyltransferase (tleD). The tleD gene, which is located outside of the tleABC cluster on the chromosome, was identified by transcriptional analysis and heterologous expression. Remarkably, TleD not only installs a methyl group on the geranyl moiety of the precursor but also facilitates the nucleophilic attack from the electron-rich indole to the resultant cation, to form the indole-fused six-membered ring. This is the first demonstration of a cation, generated from methylation, triggering successive terpenoid ring closure.
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5. |
Abe I,
Awakawa T,
Asakawa Y,
Zhang L,
Ito T,
Qu X,
( 2012 ) Biosynthetic pathway for high structural diversity of a common dilactone core in antimycin production. PMID : 22861048 : DOI : 10.1021/ol301785x Abstract >>
We herein report comparative analysis of two versions of the biosynthetic gene clusters of antimycins, a natural product family possessing up to 44 distinct entities. The biosynthetic pathway of antimycins is amenable to the high structural variation of the substrates, supported by successes in heterologous expression of the ant cluster and in fluorine incorporation. The latter facilitated the investigation of the structure-activity relationship into the usually invariable 3-formamidosalicylic acid moiety of the molecules.
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