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Redirecting metabolic fluxes through cofactor engineering: Role of CoA-esters pool during l(−)-carnitine production by Escherichia coli

Paper ID Volume ID Publish Year Pages File Format Full-Text
24938 43547 2007 8 PDF Available
Title
Redirecting metabolic fluxes through cofactor engineering: Role of CoA-esters pool during l(−)-carnitine production by Escherichia coli
Abstract

Cofactor engineering, defined as the purposeful modification of the pool of intracellular cofactors, has been demonstrated to be a very suitable strategy for the improvement of l(−)-carnitine production in Escherichia coli strains. The overexpression of CaiB (CoA-transferase) and CaiC (CoA-ligase), both enzymes involved in coenzyme A transfer and substrate activation during the bioprocess, led to an increase in l(−)-carnitine production. Under optimal concentrations of inducer and fumarate (used as electron acceptors) yields reached 10- and 50-fold, respectively, that obtained for the wild type strain. However, low levels of coenzyme A limited the activity of these two enzymes since the addition of pantothenate increased production. Growth on substrates whose assimilation yields acetyl-CoA (such as acetate or pyruvate) further inhibited l(−)-carnitine production. Interestingly, control steps in the metabolism of acetyl-CoA of E. coli were detected. The glyoxylate shunt and anaplerotic pathways limit the bioprocess since strains carrying deletions of isocitrate lyase and isocitrate dehydrogenase phosphatase/kinase yielded 20–25% more l(−)-carnitine than the control. On the other hand, the deletion of phosphotransacetylase strongly inhibited the bioprocess, suggesting that an adequate flux of acetyl-CoA and the connection of the phosphoenolpyruvate–glyoxylate cycle together with the acetate metabolism are crucial for the biotransformation.

Keywords
Escherichia coli; Cofactor engineering; l(−)-Carnitine; Acetyl-CoA; Glyoxylate shunt; Acetate metabolism
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Redirecting metabolic fluxes through cofactor engineering: Role of CoA-esters pool during l(−)-carnitine production by Escherichia coli
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 132, Issue 2, 31 October 2007, Pages 110–117
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us