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Scaglione, Jamie B.,Akey, David L.,Sullivan, Rachel,Kittendorf, Jeffrey D.,Rath, Christopher M.,Kim, Eung-Soo,Smith, Janet L.,Sherman, David H. WILEY-VCH Verlag 2010 Angewandte Chemie Vol.49 No.33
<B>Graphic Abstract</B> <P>A narrow tunnel: Biochemical and structural analysis of the tautomycetin thioesterase (TE) has provided the first high-resolution structure of a linear-chain-terminating TE in polyketide biosynthesis, showing the enzyme to be stereoselective with a constrained substrate chamber relative to macrolactone-forming thioesterases. <img src='wiley_img_2010/14337851-2010-49-33-ANIE201000032-content.gif' alt='wiley_img_2010/14337851-2010-49-33-ANIE201000032-content'> </P>
In vitro antimicrobial and in vivo antioomycete activities of the novel antibiotic thiobutacin
Lee, Jung Yeop,Sherman, David H,Hwang, Byung Kook John Wiley Sons, Ltd. 2008 PEST MANAGEMENT SCIENCE Vol.64 No.2
<P>BACKGROUND: A number of synthetic fungicides are not effective when confronted by oomycete pathogens because many fungicide targets are absent from oomycetes. Moreover, resistance to fungicides has already arisen in oomycete species, and thus development of new, effective and safe compounds for use in oomycete disease control is necessary.</P><P>RESULTS: Zoospore lysis began at 10 µg mL<SUP>−1</SUP> of thiobutacin, and most of the zoospores were collapsed at 50 µg mL<SUP>−1</SUP>. Thiobutacin also revealed inhibitory activity against the cyst germination and hyphal growth of Phytophthora capsici at 50 µg mL<SUP>−1</SUP>. Treatment with thiobutacin exhibited protective activity against development of Phytophthora disease on pepper plants.</P><P>CONCLUSION: The authors verified in vitro antioomycete activity of thiobutacin against P. capsici and its control efficacy against Phytophthora blight in vivo. This is the first report to demonstrate in vivo antioomycete activity of the novel antibiotic thiobutacin against P. capsici infection. Copyright © 2007 Society of Chemical Industry</P>
Lee, Mi-Jin,Kong, Dekun,Han, Kyuboem,Sherman, David H,Bai, Linquan,Deng, Zixin,Lin, Shuangjun,Kim, Eung-Soo Springer International 2012 Applied microbiology and biotechnology Vol.95 No.1
<P>Polyene antibiotics such as nystatin are a large family of very valuable antifungal polyketide compounds typically produced by soil actinomycetes. Previously, using a polyene cytochrome P450 hydroxylase-specific genome screening strategy, Pseudonocardia autotrophica KCTC9441 was determined to contain an approximately 125.7-kb region of contiguous DNA with a total of 23 open reading frames, which are involved in the biosynthesis and regulation of a structurally unique polyene natural product named NPP. Here, we report the complete structure of NPP, which contains an aglycone identical to nystatin and harbors a unique di-sugar moiety, mycosaminyl-(α1-4)-N-acetyl-glucosamine. A mutant generated by inactivation of a sole glycosyltransferase gene (nppDI) within the npp gene cluster can be complemented in trans either by nppDI-encoded protein or by its nystatin counterpart, NysDI, suggesting that the two sugars might be attached by two different glycosyltransferases. Compared with nystatin (which bears a single sugar moiety), the di-sugar containing NPP exhibits approximately 300-fold higher water solubility and 10-fold reduced hemolytic activity, while retaining about 50% antifungal activity against Candida albicans. These characteristics reveal NPP as a promising candidate for further development into a pharmacokinetically improved, less-cytotoxic polyene antifungal antibiotic.</P>
Choi, Si-Sun,Hur, Yoon-Ah,Sherman, David H,Kim, Eung-Soo Microbiology Society 2007 Microbiology Vol.153 No.4
<P>The bacterial genus Streptomyces has long been appreciated for its ability to produce various kinds of medically important secondary metabolites, such as antibiotics, anti-tumour agents, immunosuppressants and enzyme inhibitors. Tautomycetin (TMC), which is produced by Streptomyces sp. CK4412, is a novel activated T cell-specific immunosuppressive compound with an ester bond linkage between a terminal cyclic anhydride moiety and a linear polyketide chain bearing an unusual terminal alkene. Using a Streptomyces polyketide methylmalonyl-CoA acyltransferase gene as a probe, three overlapping cosmids were isolated from the genomic library of TMC-producing Streptomyces sp. CK4412. Sequence information of an approximately 70 kb contiguous DNA region revealed two multi-modular type I polyketide synthases (PKSs), and 12 additional gene products presumably involved in TMC biosynthesis. The deduced roles for most of the TMC PKS catalytic domains were consistent with the expected functions necessary for TMC chain elongation and processing. In addition, disruption of a putative TMC acyl-CoA transferase gene, located upstream of the PKS gene locus, completely abolished TMC biosynthesis. Taken together, these data provide strong supporting evidence that the cloned gene cluster identified in this study is responsible for TMC biosynthesis in Streptomyces sp. CK4412, and set the stage for detailed genetic and biochemical studies of the biosynthesis of this important metabolite.</P>
JUNG, WON-SEOK,KIM, EUNG-SOO,KANG, HAN-YOUNG,CHOI, CHA-YONG,SHERMAN, DAVID H.,YOON, YEO JOON 한국미생물 · 생명공학회 2003 Journal of microbiology and biotechnology Vol.13 No.5
Streptomyces venezuelae ATCC 15439 is notable in its ability to produce two distinct groups of macrolactones. It has been reported that the generation of two macrolactone structures results from alternative expression of pikromycin (Pik) polyketide synthase (PKS). It was previously reported that the hybrid pikromycin-tylosin PKS can also produce two different macrolactones but its mechanistic basis remains unclear. In order to address this question, a series of site-directed mutagenesis of tentative alternative ribosome binding site and translation start codons in rylGV were performed. The results suggest that macrolactone ring size is not determined by the alternative expression of Ty/GV but through other mechanism(s) involving direct interaction between the PikAⅢ and TE domain or skipping of the final chain elongation step. This provides new insight into the mechanism of macrolactone ring size determination in hybrid PKS as well as an opportunity to develop novel termination activities for combinatorial biosynthesis.