32885-75-9Relevant articles and documents
Accumulation of narbonolide by the addition of sodium arsenite
Maezawa,Hori,Suzuki
, p. 539 - 542 (1974)
Addition of sodium arsenite to the fermentation medium of Streptomyces venezuelae MCRL 0376 caused an inhibition of antibiotic production and a simultaneous accumulation of narbonolide, the aglycone of narbomycin. The accumulation of narbonolide was not observed in the absence of sodium arsenite. The inhibition of antibiotic production by sodium arsenite was not reversed by sodium acetate in contrast to erythromycin fermentation.
Engineering the Substrate Specificity of a Modular Polyketide Synthase for Installation of Consecutive Non-Natural Extender Units
Kalkreuter, Edward,Crowetipton, Jared M.,Lowell, Andrew N.,Sherman, David H.,Williams, Gavin J.
, p. 1961 - 1969 (2019)
There is significant interest in diversifying the structures of polyketides to create new analogues of these bioactive molecules. This has traditionally been done by focusing on engineering the acyltransferase (AT) domains of polyketide synthases (PKSs) responsible for the incorporation of malonyl-CoA extender units. Non-natural extender units have been utilized by engineered PKSs previously; however, most of the work to date has been accomplished with ATs that are either naturally promiscuous and/or located in terminal modules lacking downstream bottlenecks. These limitations have prevented the engineering of ATs with low native promiscuity and the study of any potential gatekeeping effects by domains downstream of an engineered AT. In an effort to address this gap in PKS engineering knowledge, the substrate preferences of the final two modules of the pikromycin PKS were compared for several non-natural extender units and through active site mutagenesis. This led to engineering of the methylmalonyl-CoA specificity of both modules and inversion of their selectivity to prefer consecutive non-natural derivatives. Analysis of the product distributions of these bimodular reactions revealed unexpected metabolites resulting from gatekeeping by the downstream ketoreductase and ketosynthase domains. Despite these new bottlenecks, AT engineering provided the first full-length polyketide products incorporating two non-natural extender units. Together, this combination of tandem AT engineering and the identification of previously poorly characterized bottlenecks provides a platform for future advancements in the field.
Substrate controlled divergence in polyketide synthase catalysis
Hansen, Douglas A.,Koch, Aaron A.,Sherman, David H.
, p. 3735 - 3738 (2015)
Biochemical characterization of polyketide synthases (PKSs) has relied on synthetic substrates functionalized as electrophilic esters to acylate the enzyme and initiate the catalytic cycle. In these efforts, N-acetylcysteamine thioesters have typically been employed for in vitro studies of full PKS modules as well as excised domains. However, substrate engineering approaches to control the catalytic cycle of a full PKS module harboring multiple domains remain underexplored. This study examines a series of alternatively activated native hexaketide substrates on the catalytic outcome of PikAIV, the sixth and final module of the pikromycin (Pik) pathway. We demonstrate the ability to control product formation with greater than 10:1 selectivity for either full module catalysis, leading to a 14-membered macrolactone, or direct cyclization to a 12-membered ring. This outcome was achieved through modifying the type of hexaketide ester employed, demonstrating the utility of substrate engineering in PKS functional studies and biocatalysis.
Frontiers and opportunities in chemoenzymatic synthesis
Mortison, Jonathan D.,Sherman, David H.
scheme or table, p. 7041 - 7051 (2010/12/20)
Natural product biosynthetic pathways have evolved enzymes with myriad activities that represent an expansive array of chemical transformations for constructing secondary metabolites. Recently, harnessing the biosynthetic potential of these enzymes through chemoenzymatic synthesis has provided a powerful tool that often rivals the most sophisticated methodologies in modern synthetic chemistry and provides new opportunities for accessing chemical diversity. Herein, we describe our research efforts with enzymes from a broad collection of biosynthetic systems, highlighting recent progress in this exciting field.
