Robert McDaniel

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Polyketide synthases (PKSs) are multifunctional enzymes that catalyze the biosynthesis of a huge variety of carbon chains differing in their length and patterns of functionality and cyclization. Many polyketides are valuable therapeutic agents. A Streptomyces host-vector system has been developed for efficient construction and expression of recombinant(More)
BACKGROUND Recently developed tools for the genetic manipulation of modular polyketide synthases (PKSs) have advanced the development of combinatorial biosynthesis technologies for drug discovery. Although many of the current techniques involve engineering individual domains or modules of the PKS, few experiments have addressed the ability to combine entire(More)
The electrostatic properties of charged bilayers and the bilayer component of biological membranes are often described theoretically by assuming the charge is smeared uniformly over the surface. This is one of the fundamental assumptions in the Gouy-Chapman-Stern (GCS) theory. However, the average distance between the charged phospholipids in a typical(More)
A putative catalytic triad consisting of tyrosine, serine, and lysine residues was identified in the ketoreductase (KR) domains of modular polyketide synthases (PKSs) based on homology modeling to the short chain dehydrogenase/reductase (SDR) superfamily of enzymes. This was tested by constructing point mutations for each of these three amino acid residues(More)
Megalomicin is a therapeutically diverse compound which possesses antiparasitic, antiviral and antibacterial properties. It is produced by Micromonospora megalomicea and differs from the well-known macrolide antibiotic erythromycin by the addition of a unique deoxyamino sugar, megosamine, to the C-6 hydroxyl. We have cloned and sequenced a 48 kb segment of(More)
Recent advances in understanding of bacterial aromatic polyketide biosynthesis allow the development of a set of design rules for the rational manipulation of chain synthesis, reduction of keto groups and early cyclization steps by genetic engineering. The concept of rational design is illustrated by the preparation of Streptomyces strains that produce two(More)
Cassette replacement of acyltransferase (AT) domains in 6-deoxyerythronolide B synthase (DEBS) with heterologous AT domains with different substrate specificities usually yields the predicted polyketide analogues. As reported here, however, several AT replacements in module 4 of DEBS failed to produce detectable polyketide under standard conditions,(More)
The structures of complex polyketide natural products, such as erythromycin, are programmed by multifunctional polyketide synthases (PKSs) that contain modular arrangements of functional domains. The colinearity between the activities of modular PKS domains and structure of the polyketide product portends the generation of novel organic(More)
Development of natural products for therapeutic use is often hindered by limited availability of material from producing organisms. The speed at which current technologies enable the cloning, sequencing, and manipulation of secondary metabolite genes for production of novel compounds has made it impractical to optimize each new organism by conventional(More)
We measured the electrophoretic mobility of multilamellar phospholipid vesicles, the 31P NMR spectra of both sonicated and multilamellar vesicles, and the conductance of planar bilayer membranes to study the binding of spermine and gentamicin to membranes. Spermine and gentamicin do not bind significantly to the zwitterionic lipid phosphatidylcholine. We(More)