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Improvement of xylose uptake and ethanol production in recombinant Saccharomyces cerevisiae through an inverse metabolic engineering approach.

Abstract：

:We used an inverse metabolic engineering approach to identify gene targets for improved xylose assimilation in recombinant Saccharomyces cerevisiae. Specifically, we created a genomic fragment library from Pichia stipitis and introduced it into recombinant S. cerevisiae expressing XYL1 and XYL2. Through serial subculturing enrichment of the transformant library, 16 transformants were identified and confirmed to have a higher growth rate on xylose. Sequencing of the 16 plasmids isolated from these transformants revealed that the majority of the inserts (10 of 16) contained the XYL3 gene, thus confirming the previous finding that XYL3 is the consensus target for increasing xylose assimilation. Following a sequential search for gene targets, we repeated the complementation enrichment process in a XYL1 XYL2 XYL3 background and identified 15 fast-growing transformants, all of which harbored the same plasmid. This plasmid contained an open reading frame (ORF) designated PsTAL1 based on a high level of homology with S. cerevisiae TAL1. To further investigate whether the newly identified PsTAL1 ORF is responsible for the enhanced-growth phenotype, we constructed an expression cassette containing the PsTAL1 ORF under the control of a constitutive promoter and transformed it into an S. cerevisiae recombinant expressing XYL1, XYL2, and XYL3. The resulting recombinant strain exhibited a 100% increase in the growth rate and a 70% increase in ethanol production (0.033 versus 0.019 g ethanol/g cells . h) on xylose compared to the parental strain. Interestingly, overexpression of PsTAL1 did not cause growth inhibition when cells were grown on glucose, unlike overexpression of the ScTAL1 gene. These results suggest that PsTAL1 is a better gene target for engineering of the pentose phosphate pathway in recombinant S. cerevisiae.

journal_name

Appl Environ Microbiol

journal_title

Applied and environmental microbiology

authors

Jin YS,Alper H,Yang YT,Stephanopoulos G

doi

10.1128/AEM.71.12.8249-8256.2005

keywords:

subject

Has Abstract

pub_date

2005-12-01 00:00:00

pages

8249-56

issue

eissn

0099-2240

issn

1098-5336

pii

71/12/8249

journal_volume

pub_type

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Improvement of xylose uptake and ethanol production in recombinant Saccharomyces cerevisiae through an inverse metabolic engineering approach.