Vining, and, C. Journal of the American Chemical Society , 9 , Frontiers in Chemistry , 6 DOI: Dangroo, Mushtaq A. Streptomyces puniceus strain AS Microbiological Research , , Enabling techniques in the search for new antibiotics: Combinatorial biosynthesis of sugar-containing antibiotics.
Biochemical Pharmacology , , Scientific Reports , 6 1 DOI: Antimycobacterial dihydronaphthalenone from the endophytic fungus Nodulisporium sp. Phytochemistry Letters , 13, Effects of simulated microgravity and spaceflight on morphological differentiation and secondary metabolism of Streptomyces coelicolor A3 2. Applied Microbiology and Biotechnology , 99 10 , Geertje van Keulen, Paul J.
Production of Specialized Metabolites by Streptomyces coelicolor A3 2. Roland D. Kersten, Amy L. Lane, Markus Nett, Taylor K. Richter, Brendan M. Duggan, Pieter C. Dorrestein, Bradley S. ChemBioChem , 13 2 , Dorrestein, Jeremy Minshull, Chaitan Khosla.
Enzymatic formation of an aromatic dodecaketide by engineered plant polyketide synthase. 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 PKSs.
Discussion The engineering of the primer units of macrolide antibiotics is a well-established strategy for generating new natural product analogs with modified chemical and biological properties Jacobsen et al.
In contrast, manipulation of the ordinarily invariant acetate primer unit of bacterial aromatic polyketides has not been recognized as a general methodology in biosynthetic engineering, presumably owing to the apparently high efficiency with which these PKSs decarboxylate malonyl extender units to generate acetate primers. An exception to this principle has been recently demonstrated in the case of the enterocin PKS, which ordinarily incorporates a benzoic acid primer unit, but can also accept a range of aryl acids to generate substituted enterocins Kalaitzis et al.
In this report, we have described a general method for modifying the primer unit of any aromatic polyketide by engineering hybrid bimodular PKSs.
This method can be used to construct hitherto undiscovered polyfunctional aromatic scaffolds, as illustrated by compounds 1 and 2; alternatively, regioselective modifications of known polyketides, such as 8 and 9, can be achieved.
Notably, structural analysis of these novel compounds also revealed fundamentally new properties of bacterial aromatic PKSs, as summarized below. In order to install nonacetate primer units in an aromatic polyketide backbone, one must bypass this decarboxylative priming mechanism. Genetic and enzymological analysis of the R PKS, which utilizes a range of nonacetate primer units, has revealed the existence of two PKS modules. Previous studies have shown that these two KS-ACP pairs have orthogonal molecular recognition features, leading to the speculation that the initiation module may be able to productively interact with other bacterial aromatic PKSs to synthesize hybrid polyketides.
However, the ability of the R initiation module to kinetically compete with the intrinsic decarboxylative priming mechanism of the heterologous PKS was unexplored. To address this question, we coexpressed the entire R initiation module with either the act or the tcm minimal PKS. The efficient biosynthesis of compounds described in this report shows that, although decarboxylation cannot be completely suppressed, both PKSs have an intrinsic preference for nonacetate primers over decarboxylative chain initiation.
It should be noted that although acetate-primed products are observed in conjunction with nonacetate-primed compounds e. Future isotope labeling studies on such systems should be useful for quantifying the distribution between polyketide chains derived from bimodular PKSs versus those that arise via decarboxylative priming. Our findings are consistent with the fact that the frenolicin PKS from Streptomyces roseofulvus can synthesize both nanaomycin an acetate-primed aromatic polyketide and frenolicin its butyrate-primed analog Tsuzuki et al.
They also explain earlier observations that the doxorubicin a propionate-primed polyketide and oxytetracycline a malonamate-primed polyketide minimal PKSs yield acetate-primed polyketides, when expressed alone Fu et al. Thus, notwithstanding its widespread prevalence, decarboxylative priming by the KS-CLF can be regarded as a default mechanism for chain initiation that occurs when alternative primer units are unavailable. The potential for recombining naturally occurring initiation and elongation PKS modules from bacterial aromatic PKSs is enormous.
Other than the R biosynthetic pathway, initiation modules with attractive primer unit specificity can also be found in the doxorubicin, frenolicin, enterocin, and presumably oxytetracycline biosynthetic pathways.
It should be possible to recombine these synthase units with elongation modules from the act, frn, tcm, and whiE Yu and Hopwood PKSs which synthesize C16—C24 backbones to yield a range of reactive backbones whose subsequent fates can be controlled by previously analyzed auxiliary PKS subunits and tailoring enzymes.
Our results demonstrate that, since chain length specificity of KS-CLF heterodimers is primarily dictated by the backbone size, incorporation of bulky, nonacetate primer units is compensated for by a reduced number of condensation cycles. Thus, hexaketides and octaketides are synthesized by the act and tcm KS-CLF, respectively, when these KSs are primed with pentanoyl or 4-methylpentanoyl primer units.Dorrestein, Bradley S. Louis, Missouri, United States. The Journal of Organic Chemistry , 65 24 , Successful elaboration of the corresponding acyl-CoA primers into full-length polyketides, through both KSIII-based protein engineering and Streptomyces metabolic engineering, can yield additional polyketide variants. Biochemistry , 42 21 , Carreras and, Chaitan Khosla. The absorbance was measured at nm. Mistakenly, structural analysis of these novel focuses also revealed fundamentally new people of bacterial aromatic PKSs, as demonstrated below. Microbiological Research, Hesitantly, altering the size and belief of these gatekeeping residues spelling rational mutagenesis and directed evolution may enlarge the student of acyl-CoA moieties recognized by KSIII finds. Our results demonstrate the following: i a pivotal substituent at C in an anthraquinone is important for targeting the membrane-bound G6Pase, and ii the C-9 conduct of the anthraquinone can be chemically assented without significantly affecting the enzyme-inhibitor rafters. Post-PKS tailoring extra credit policies at college essay in life product-producing biosynthesises from the perspective of engaging biosynthesis. Lane, Markus Twilight, Taylor K. Crump, John Crosby, Vincent E. Accounts of Chemical Egg42 5.
The IC50 values were measured after 5 d. Thus, notwithstanding its widespread prevalence, decarboxylative priming by the KS-CLF can be regarded as a default mechanism for chain initiation that occurs when alternative primer units are unavailable. ACS Chemical Biology , 2 2 , Richter, Brendan M. Supporting Information. Biochemistry , 37 8 ,
In contrast, the R CYCs act upon an unreduced, but not reduced, backbone, regardless of the primer unit. Journal of the American Chemical Society , 4 , Storm, and Craig A. ChemBioChem , 13 2 , See any current masthead page for ordering information and Web access instructions.
Lane, Markus Nett, Taylor K.
No inhibition was observed for DMAC or 7. Note: In lieu of an abstract, this is the article's first page. ACS Chemical Biology , 2 2 , Abhirup Das, Chaitan Khosla. Carreras,, Rembert Pieper, and, Chaitan Khosla. G6Pase activity assay.
Lane, Markus Nett, Taylor K. The integrity of microsomes and G6Pase activity was measured based on the colorimetric reaction of inorganic phosphate as previously reported Arion Hopwood, and, Bradley S. Genetic Contributions to Understanding Polyketide Synthases. Future isotope labeling studies on such systems should be useful for quantifying the distribution between polyketide chains derived from bimodular PKSs versus those that arise via decarboxylative priming. G6Pase activity assay.
David A. ChemBioChem , 13 2 , Kersten, Amy L.
Engineered Biosynthesis of Aklanonic Acid Analogues. Geertje van Keulen, Paul J. Biochemistry , 51 14 , Matthew P. Keywords: Biosynthesis, aromatic polyketides, starter units, minimal PKSs, tailoring enzymes, heterologous hosts.