scholarly journals Mechanism and Stereochemistry of Polyketide Chain Elongation and Methyl Group Epimerization in Polyether Biosynthesis

2017 ◽  
Vol 139 (8) ◽  
pp. 3283-3292 ◽  
Author(s):  
Xinqiang Xie ◽  
Ashish Garg ◽  
Chaitan Khosla ◽  
David E. Cane
Keyword(s):  
Chain Elongation ◽  
Methyl Group ◽  
Polyketide Chain

Macrolide biosynthesis. 6 Mechanism of polyketide chain elongation

1991 ◽  
Vol 32 (40) ◽  
pp. 5457-5460 ◽  
Author(s):  
David E. Cane ◽  
P.C. Prabhakaran ◽  
Weitian Tan ◽  
Walter R. Ott
Keyword(s):  
Chain Elongation ◽  
Polyketide Chain

Macrolide biosynthesis. 7. Incorporation of polyketide chain elongation intermediates into methymycin

1993 ◽  
Vol 115 (2) ◽  
pp. 522-526 ◽  
Author(s):  
David E. Cane ◽  
Ralph H. Lambalot ◽  
P. C. Prabhakaran ◽  
Walter R. Ott
Keyword(s):  
Chain Elongation ◽  
Polyketide Chain

ChemInform Abstract: Macrolide Biosynthesis. Part 7. Incorporation of Polyketide Chain Elongation Intermediates into Methymycin.

ChemInform ◽  
2010 ◽  
Vol 24 (21) ◽  
pp. no-no
Author(s):  
D. E. CANE ◽  
R. H. LAMBALOT ◽  
P. C. PRABHAKARAN ◽  
W. R. OTT
Keyword(s):  
Chain Elongation ◽  
Polyketide Chain

scholarly journals Thioesterases and the Premature Termination of Polyketide Chain Elongation in Rifamycin B Biosynthesis by Amycolatopsis mediterranei S699.

2000 ◽  
Vol 53 (5) ◽  
pp. 484-495 ◽  
Author(s):  
YUKIKO DOI-KATAYAMA ◽  
YEO JOON YOON ◽  
CHA-YONG CHOI ◽  
TIN-WEIN YU ◽  
HEINZ G. FLOSS ◽  
...  
Keyword(s):  
Premature Termination ◽  
Chain Elongation ◽  
Amycolatopsis Mediterranei ◽  
Polyketide Chain ◽  
Rifamycin B

scholarly journals Evidence for an iterative module in chain elongation on the azalomycin polyketide synthase

2016 ◽  
Vol 12 ◽  
pp. 2164-2172 ◽  
Author(s):  
Hui Hong ◽  
Yuhui Sun ◽  
Yongjun Zhou ◽  
Emily Stephens ◽  
Markiyan Samborskyy ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Polyketide Synthase ◽  
Strong Support ◽  
Artificial Chromosome ◽  
Chain Extension ◽  
Chain Elongation ◽  
Starter Unit ◽  
Polyketide Chain ◽  
Streptomyces Olivaceus ◽  
Streptomyces Malaysiensis

The assembly-line synthases that produce bacterial polyketide natural products follow a modular paradigm in which each round of chain extension is catalysed by a different set or module of enzymes. Examples of deviation from this paradigm, in which a module catalyses either multiple extensions or none are of interest from both a mechanistic and an evolutionary viewpoint. We present evidence that in the biosynthesis of the 36-membered macrocyclic aminopolyol lactones (marginolactones) azalomycin and kanchanamycin, isolated respectively from Streptomyces malaysiensis DSM4137 and Streptomyces olivaceus Tü4018, the first extension module catalyses both the first and second cycles of polyketide chain extension. To confirm the integrity of the azl gene cluster, it was cloned intact on a bacterial artificial chromosome and transplanted into the heterologous host strain Streptomyces lividans, which does not possess the genes for marginolactone production. When furnished with 4-guanidinobutyramide, a specific precursor of the azalomycin starter unit, the recombinant S. lividans produced azalomycin, showing that the polyketide synthase genes in the sequenced cluster are sufficient to accomplish formation of the full-length polyketide chain. This provides strong support for module iteration in the azalomycin and kanchanamycin biosynthetic pathways. In contrast, re-sequencing of the gene cluster for biosynthesis of the polyketide β-lactone ebelactone in Streptomyces aburaviensis has shown that, contrary to a recently-published proposal, the ebelactone polyketide synthase faithfully follows the colinear modular paradigm.

scholarly journals The Methyl Group of theN6-Methyl-N6-Threonylcarbamoyladenosine in tRNA of Escherichia coli Modestly Improves the Efficiency of the tRNA

1998 ◽  
Vol 180 (7) ◽  
pp. 1808-1813 ◽  
Author(s):  
Qiang Qian ◽  
James F. Curran ◽  
Glenn R. Björk
Keyword(s):  
Escherichia Coli ◽  
Wild Type Strain ◽  
Chain Elongation ◽  
Methyl Group ◽  
E Coli ◽  
Trna Species ◽  
A Site ◽  
Chromosomal Map ◽  
Threonine Operon ◽  
Selection Of

ABSTRACT tRNA species that read codons starting with adenosine (A) containN 6-threonylcarbamoyladenosine (t6A) derivatives adjacent to and 3′ of the anticodons from all organisms. InEscherichia coli there are 12 such tRNA species of which two (tRNAGGU Thr1 and tRNAGGU Thr3) have the t6A derivativeN 6-methyl-N 6-threonylcarbamoyladenosine (m6t6A37). We have isolated a mutant ofE. coli that lacks the m6t6A37 in these two tRNAGGU Thr species. These tRNA species in the mutant are likely to have t6A37 instead of m6t6A37. We show that the methyl group of m6t6A37 originates fromS-adenosyl-l-methionine and that the gene (tsaA) which most likely encodes tRNA(m6t6A37)methyltransferase is located at min 4.6 on the E. coli chromosomal map. The growth rate of the cell, the polypeptide chain elongation rate, and the selection of Thr-tRNAGGU Thr to the ribosomal A site programmed with either of the cognate codons ACC and ACU were the same for thetsaA1 mutant as for the congenic wild-type strain. The expression of the threonine operon is regulated by an attenuator which contains in its leader mRNA seven ACC codons that are read by these two m6t6A37-containing tRNAGGU Thrspecies. We show that the tsaA1 mutation resulted in a twofold derepression of this operon, suggesting that the lack of the methyl group of m6t6A37 in tRNAGGU Thr slightly reduces the efficiency of this tRNA to read cognate codon ACC.

scholarly journals Reconstitution of the FK228 Biosynthetic Pathway Reveals Cross Talk between Modular Polyketide Synthases and Fatty Acid Synthase

2010 ◽  
Vol 77 (4) ◽  
pp. 1501-1507 ◽  
Author(s):  
Shane R. Wesener ◽  
Vishwakanth Y. Potharla ◽  
Yi-Qiang Cheng
Keyword(s):  
Fatty Acid ◽  
Cross Talk ◽  
Biosynthetic Pathway ◽  
Fatty Acid Synthase ◽  
Polyketide Synthase ◽  
Fatty Acid Biosynthesis ◽  
Chain Elongation ◽  
E Coli ◽  
Genetic Components ◽  
Polyketide Chain

ABSTRACTFunctional cross talk between fatty acid biosynthesis and secondary metabolism has been discovered in several cases in microorganisms; none of them, however, involves a modular biosynthetic enzyme. Previously, we reported a hybrid modular nonribosomal peptide synthetase (NRPS)-polyketide synthase (PKS) pathway for the biosynthesis of FK228 anticancer depsipeptide inChromobacterium violaceumstrain 968. This pathway contains two PKS modules on the DepBC enzymes that lack a functional acyltransferase (AT) domain, and no apparent AT-encoding gene exists within the gene cluster or its vicinity. We report here that, through reconstitution of the FK228 biosynthetic pathway inEscherichia colicells, two essential genes,fabD1andfabD2, both encoding a putative malonyl coenzyme A (CoA) acyltransferase component of the fatty acid synthase complex, are positively identified to be involved in FK228 biosynthesis. Either gene product appears sufficient to complement the AT-less PKS modules on DepBC for polyketide chain elongation. Concurrently, a gene (sfp) encoding a putative Sfp-type phosphopantetheinyltransferase was identified to be necessary for FK228 biosynthesis as well. Most interestingly, engineeredE. colistrains carrying variable genetic components produced significant levels of FK228 under both aerobic and anaerobic cultivation conditions. Discovery of thetranscomplementation of modular PKSs by housekeeping ATs reveals natural product biosynthesis diversity. Moreover, demonstration of anaerobic production of FK228 by an engineered facultative bacterial strain validates our effort toward the engineering of novel tumor-targeting bioagents.

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