Macrolide biosynthesis.  3.  Stereochemistry of the chain-elongation steps of erythromycin biosynthesis

Cane, David E.; Liang, Tzyy Chyau; Taylor, Paul B.; Chang, Ching‐Fong; Yang, Chi Ching

doi:10.1021/ja00276a042

Cited by 60 publications

(33 citation statements)

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“…10. By analogy with the stereochemistry of erythromycin polyketide synthase (5,6), it appears plausible that the C 8 precursor could be carboxylated yielding a S-hexylmalonyl intermediate (compound 6). A decarboxylative condensation could then proceed by inversion of this chiral center yielding intermediate 7 with a 2R configuration.…”

Section: Resultsmentioning

confidence: 99%

Biosynthetic Origin of Hydrogen Atoms in the Lipase Inhibitor Lipstatin

Goese

Eisenreich

Kupfer

et al. 2000

Journal of Biological Chemistry

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Section: Resultsmentioning

confidence: 99%

Biosynthetic Origin of Hydrogen Atoms in the Lipase Inhibitor Lipstatin

Goese

Eisenreich

Kupfer

et al. 2000

Journal of Biological Chemistry

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“…Based on the polyketide paradigm, 6-dEB was suggested to be synthesized via repetitive decarboxylative condensations between a propionyl-CoA primer and six methylmalonyl CoA extenders. Using a variety of 13C-, t80-, 2H-, and multiple-labeled substrates and advanced intermediate analogs, Cane and coworkers concluded that the biosynthesis of 6-dEB involves a processive mechanism in which the final reduction state and the stereochemistry of each of the carbons is set directly after the condensation reaction between the growing intermediate and a methylmalonyl extender [143][144][145][146][147]. Notwithstanding these advances, direct insights into the structure and properties of the enzymes responsible for 6-dEB biosynthesis did not emerge until the cloning and DNA sequencing of the erythromycin gene cluster [24].…”

Section: -Deoxyerythronolide B Synthasementioning

confidence: 99%

The chemistry and biology of fatty acid, polyketide, and nonribosomal peptide biosynthesis

Carreras

Pieper

Khosla

1997

Topics in Current Chemistry

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Polyketide synthases, fatty acid synthases, and non-ribosomal peptide synthetases are a structurally and mechanistically related class of enzymes that catalyze the synthesis of biopolymers in the absence of a nucleic acid or other template. These enzymes utilize the common mechanistic feature of activating monomers for condensation via covalently-bound thioesters of phosphopantetheine prosthetic groups. The information for the sequence and length of the resulting polymer appears to be encoded entirely within the responsible proteins.Polyketide and fatty acid biosyntheses begin with condensation of the coenzyme A thioester of a short-chain carboxylic acid "starter unit" such as acetate or propionate with the coenzyme A thioester of a dicarboxylic acid "extender unit" such as malonate or methyl malonate. The driving force for the condensation is provided by the decarboxylation of the extender unit. In the case of fatty acid synthesis, the resulting fl-carbonyl is completely reduced to a methylene; however, during the synthesis of complex polyketides, the fl-carbonyl may be left untouched or variably reduced to alcohol, olefinic, or methylene functionalities depending on the position that the extender unit will occupy in the final product. This cycle is repeated, and the number of elongation cycles is a characteristic of the enzyme catalyst. In polyketide biosynthesis, the full-length polyketide chain cyclizes in a specific manner, and is tailored by the action of additional enzymes in the pathway.Several architectural paradigms are known for polyketide and fatty acid synthases. While the bacterial enzymes are composed of several monofunctional polypeptides which are used during each cycle of chain elongation, fatty acid and polyketide synthases in higher organisms are multifunctional proteins with an individual set of active sites dedicated to each cycle of condensation and ketoreduction. Peptide synthetases also exhibit a one-to-one correspondence between the enzyme sequence and the structure of the product. Together, these systems represent a unique mechanism for the synthesis of biopolymers in which the template and the catalyst are the same molecule.

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“…The individual modules are, in turn, made up of a set of catalytic domains of 100 ± 400 amino acids, each of which is similar in both function and amino acid sequence to the analogous enzymes of fatty acid biosynthesis. The polyketide chain-building step is a decarboxylative condensation reaction catalyzed by a b-ketoacyl-ACP synthase (b-ketosynthase, KS) domain [4]. Almost all PKS modules possess a core set of three domains: a bketosynthase (KS), an acyl transferase (AT), and an acyl carrier protein (ACP) domain.…”

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confidence: 99%

“…Enzymatic Conversion of Branched-Chain Diketides to Triketide Lactones. To probe further the biochemical basis for the apparent stereoselectivity for the (4R)-methyl branched-chain diketide 4 compared to its diastereoisomer, (4S)-3, we carried out individual incubations of both 3 and 4 with isolated DEBS module 2 TE [18] in the presence of [2][3][4][5][6][7][8][9][10][11][12][13][14] C]methylmalonyl-CoA and NADPH to give the expected triketide lactones 13 and 14, as determined by radio-TLC/phosphoimaging (Scheme 5). We then carried out a series of incubations with varying concentrations of each substrate (Fig.…”

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confidence: 99%

“…Competition experiments were also carried out with DEBS module 2 TE in which variable concentrations of natural diketide 2 were incubated with [2][3][4][5][6][7][8][9][10][11][12][13][14] C]methylmal-onyl-CoA and NADPH in the presence of 0, 0.2, and 0.5 mm 4, with the formation of triketide lactone 12 assayed by TLC/phosphoimaging. As is evident from the double reciprocal LineweaverÀBurk plot for these reactions (Fig.…”

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Precursor‐Directed Biosynthesis: Stereospecificity for Branched‐Chain Diketides of the β‐Ketoacyl‐ACP Synthase Domain 2 of 6‐Deoxyerythronolide B Synthase

Kinoshita¹,

Khosla²,

Cane³

2003

Helvetica Chimica Acta

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Modular polyketide synthases such as 6‐deoxyerythronolide B synthase (DEBS) catalyze the biosynthesis of structurally complex natural products. Streptomyces coelicolor CH999/pJRJ2 harbors a plasmid encoding DEBS(KS10), a mutant form of 6‐deoxyerythronolide B synthase that is blocked in the formation of 6‐deoxyerythronolide B (1, 6‐dEB) due to a mutation in the active site of the ketosynthase (KS1) domain that normally catalyzes the first polyketide chain‐elongation step of 6‐dEB biosynthesis. Administration of (2S,3R,4S)‐ and (2S,3R,4R)‐3‐hydroxy‐2,4‐dimethylhexanoic acid N‐acetylcysteamine (SNAC) thioesters (= S‐[2‐(acetylamino)ethyl] (2S,3R,4S)‐ and (2S,3R,4R)‐3‐hydroxy‐2,4‐dimethylhexanethioates) 3 and 4 in separate experiments to cultures of Streptomyces coelicolor CH999/pJRJ2 led to production of the corresponding (14S)‐ and (14R)‐14‐methyl analogues of 6‐dEB, 10 and 11, respectively. Unexpectedly, when a 3 : 2 mixture of 4 and 3 was fed under the same conditions, exclusively branched‐chain macrolactone 11 was isolated. In similar experiments, feeding of 3 and 4 to S. coelicolor CH999/pCK16, an engineered strain harboring DEBS1+TE(KS10), resulted in formation of the branched‐chain triketide lactones 13 and 14, while feeding of the 3 : 2 mixture of 4 and 3 gave exclusively 14. The biochemical basis for this stereochemical discrimination was established by using purified DEBS module 2+TE to determine the steady‐state kinetic parameters for 3 and 4, with the kcat/KM for 4 shown to be sevenfold greater than that of 3.

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Macrolide biosynthesis. 3. Stereochemistry of the chain-elongation steps of erythromycin biosynthesis

Cited by 60 publications

References 0 publications

Biosynthetic Origin of Hydrogen Atoms in the Lipase Inhibitor Lipstatin

Biosynthetic Origin of Hydrogen Atoms in the Lipase Inhibitor Lipstatin

The chemistry and biology of fatty acid, polyketide, and nonribosomal peptide biosynthesis

Precursor‐Directed Biosynthesis: Stereospecificity for Branched‐Chain Diketides of the β‐Ketoacyl‐ACP Synthase Domain 2 of 6‐Deoxyerythronolide B Synthase

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