Photochemistry of 4-hydroxy-6-methyl-(2H)-pyran-2-one (triacetic acid lactone)

1969 ◽  
pp. 685 ◽  
Author(s):  
C. T. Bedford ◽  
T. Money
Keyword(s):  
Acid Lactone ◽  
Triacetic Acid Lactone

scholarly journals Engineering sensitivity and specificity of AraC-based biosensors responsive to triacetic acid lactone and orsellinic acid

2020 ◽  
Vol 33 ◽  
Author(s):  
Zhiqing Wang ◽  
Aarti Doshi ◽  
Ratul Chowdhury ◽  
Yixi Wang ◽  
Costas D Maranas ◽  
...  
Keyword(s):  
Directed Evolution ◽  
Negative Selection ◽  
Regulatory Protein ◽  
Polyketide Synthases ◽  
Computational Framework ◽  
Orsellinic Acid ◽  
Acid Lactone ◽  
Triacetic Acid Lactone ◽  
Protein Redesign ◽  
Background Expression

Abstract We previously described the design of triacetic acid lactone (TAL) biosensor ‘AraC-TAL1’, based on the AraC regulatory protein. Although useful as a tool to screen for enhanced TAL biosynthesis, this variant shows elevated background (leaky) expression, poor sensitivity and relaxed inducer specificity, including responsiveness to orsellinic acid (OA). More sensitive biosensors specific to either TAL or OA can aid in the study and engineering of polyketide synthases that produce these and similar compounds. In this work, we employed a TetA-based dual-selection to isolate new TAL-responsive AraC variants showing reduced background expression and improved TAL sensitivity. To improve TAL specificity, OA was included as a ‘decoy’ ligand during negative selection, resulting in the isolation of a TAL biosensor that is inhibited by OA. Finally, to engineer OA-specific AraC variants, the iterative protein redesign and optimization computational framework was employed, followed by 2 rounds of directed evolution, resulting in a biosensor with 24-fold improved OA/TAL specificity, relative to AraC-TAL1.

scholarly journals Rewiring Yarrowia lipolytica toward triacetic acid lactone for materials generation

2018 ◽  
Vol 115 (9) ◽  
pp. 2096-2101 ◽  
Author(s):  
Kelly A. Markham ◽  
Claire M. Palmer ◽  
Malgorzata Chwatko ◽  
James M. Wagner ◽  
Clare Murray ◽  
...  
Keyword(s):  
Yarrowia Lipolytica ◽  
Building Blocks ◽  
Specific Productivity ◽  
Chemical Production ◽  
Conversion Yield ◽  
Acetyl Coa ◽  
Type Iii Polyketide Synthase ◽  
Chemical Catalysis ◽  
Acid Lactone ◽  
Triacetic Acid Lactone

Polyketides represent an extremely diverse class of secondary metabolites often explored for their bioactive traits. These molecules are also attractive building blocks for chemical catalysis and polymerization. However, the use of polyketides in larger scale chemistry applications is stymied by limited titers and yields from both microbial and chemical production. Here, we demonstrate that an oleaginous organism (specifically, Yarrowia lipolytica) can overcome such production limitations owing to a natural propensity for high flux through acetyl–CoA. By exploring three distinct metabolic engineering strategies for acetyl–CoA precursor formation, we demonstrate that a previously uncharacterized pyruvate bypass pathway supports increased production of the polyketide triacetic acid lactone (TAL). Ultimately, we establish a strain capable of producing over 35% of the theoretical conversion yield to TAL in an unoptimized tube culture. This strain also obtained an averaged maximum titer of 35.9 ± 3.9 g/L with an achieved maximum specific productivity of 0.21 ± 0.03 g/L/h in bioreactor fermentation. Additionally, we illustrate that a β-oxidation-related overexpression (PEX10) can support high TAL production and is capable of achieving over 43% of the theoretical conversion yield under nitrogen starvation in a test tube. Next, through use of this bioproduct, we demonstrate the utility of polyketides like TAL to modify commodity materials such as poly(epichlorohydrin), resulting in an increased molecular weight and shift in glass transition temperature. Collectively, these findings establish an engineering strategy enabling unprecedented production from a type III polyketide synthase as well as establish a route through O-functionalization for converting polyketides into new materials.

scholarly journals Analysis of amino acid substitutions in AraC variants that respond to triacetic acid lactone

2016 ◽  
Vol 25 (4) ◽  
pp. 804-814 ◽  
Author(s):  
Christopher S. Frei ◽  
Zhiqing Wang ◽  
Shuai Qian ◽  
Samuel Deutsch ◽  
Markus Sutter ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitutions ◽  
Acid Lactone ◽  
Triacetic Acid Lactone

scholarly journals Purification and properties of 6-methylsalicylic acid synthase from Penicillium patulum

1992 ◽  
Vol 288 (3) ◽  
pp. 839-846 ◽  
Author(s):  
J B Spencer ◽  
P M Jordan
Keyword(s):  
Fatty Acid ◽  
Proteinase Inhibitors ◽  
Type I ◽  
Acetyl Coa ◽  
Purification Method ◽  
Methylsalicylic Acid Synthase ◽  
Acid Lactone ◽  
Penicillium Patulum ◽  
Triacetic Acid Lactone

6-Methylsalicylic acid synthase has been isolated in homogeneous form from Penicillium patulum grown in liquid culture from a spore inoculum. The enzyme is highly susceptible to proteolytic degradation in vivo and in vitro, but may be stabilized during purification by incorporating proteinase inhibitors in the buffers. The enzyme exists as a homotetramer of M(r) 750,000, with a subunit M(r) of 180,000. 6-Methylsalicyclic acid synthase also accepts acetoacetyl-CoA as an alternative starter molecule to acetyl-CoA. The enzyme also catalyses the formation of small amounts of triacetic acid lactone as an oligatory by-product of the reaction. In the absence of NADPH, triacetic acid lactone is the exclusive enzymic product, being formed at 10% of the rate of 6-methylsalicylic acid. The enzyme is inactivated by 1,3-dibromopropan-2-one, leading to the formation of cross-linked dimers similar to that observed with type I fatty acid synthases. Acetyl-CoA protects the enzyme against the inactivation and inhibits dimer formation. An adaptation of the purification method for 6-methylsalicylic acid synthase may be used for the isolation of fatty acid sythase from Penicillium patulum.

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