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Exploring the xylose paradox in Saccharomyces cerevisiae through in vivo sugar signalomics of targeted deletants

Osiro, Karen O. LU ; Borgström, Celina LU ; Brink, Daniel P. LU ; Fjölnisdóttir, Birta Líf and Gorwa-Grauslund, Marie F. LU (2019) In Microbial Cell Factories 18(1).
Abstract

Background: There have been many successful strategies to implement xylose metabolism in Saccharomyces cerevisiae, but no effort has so far enabled xylose utilization at rates comparable to that of glucose (the preferred sugar of this yeast). Many studies have pointed towards the engineered yeast not sensing that xylose is a fermentable carbon source despite growing and fermenting on it, which is paradoxical. We have previously used fluorescent biosensor strains to in vivo monitor the sugar signalome in yeast engineered with xylose reductase and xylitol dehydrogenase (XR/XDH) and have established that S. cerevisiae senses high concentrations of xylose with the same signal as low concentration of glucose, which may explain the poor... (More)

Background: There have been many successful strategies to implement xylose metabolism in Saccharomyces cerevisiae, but no effort has so far enabled xylose utilization at rates comparable to that of glucose (the preferred sugar of this yeast). Many studies have pointed towards the engineered yeast not sensing that xylose is a fermentable carbon source despite growing and fermenting on it, which is paradoxical. We have previously used fluorescent biosensor strains to in vivo monitor the sugar signalome in yeast engineered with xylose reductase and xylitol dehydrogenase (XR/XDH) and have established that S. cerevisiae senses high concentrations of xylose with the same signal as low concentration of glucose, which may explain the poor utilization. Results: In the present study, we evaluated the effects of three deletions (ira2δ, isu1δ and hog1δ) that have recently been shown to display epistatic effects on a xylose isomerase (XI) strain. Through aerobic and anaerobic characterization, we showed that the proposed effects in XI strains were for the most part also applicable in the XR/XDH background. The ira2δisu1δ double deletion led to strains with the highest specific xylose consumption- and ethanol production rates but also the lowest biomass titre. The signalling response revealed that ira2δisu1δ changed the low glucose-signal in the background strain to a simultaneous signalling of high and low glucose, suggesting that engineering of the signalome can improve xylose utilization. Conclusions: The study was able to correlate the previously proposed beneficial effects of ira2δ, isu1δ and hog1δ on S. cerevisiae xylose uptake, with a change in the sugar signalome. This is in line with our previous hypothesis that the key to resolve the xylose paradox lies in the sugar sensing and signalling networks. These results indicate that the future engineering targets for improved xylose utilization should probably be sought not in the metabolic networks, but in the signalling ones.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
cAMP/PKA, GFP biosensor, Saccharomyces cerevisiae, SNF1/Mig1p, Snf3p/Rgt2p, Sugar sensing/signalling, Xylose, δhog1, δira2, δisu1
in
Microbial Cell Factories
volume
18
issue
1
article number
88
publisher
BioMed Central (BMC)
external identifiers
  • scopus:85066403980
  • pmid:31122246
ISSN
1475-2859
DOI
10.1186/s12934-019-1141-x
project
Understanding and improving microbial cell factories through Large Scale Data-approaches
language
English
LU publication?
yes
id
5585f05c-7213-4bc4-9bf0-dc9e99baac6d
date added to LUP
2019-07-04 09:23:07
date last changed
2021-01-06 03:24:35
@article{5585f05c-7213-4bc4-9bf0-dc9e99baac6d,
  abstract     = {<p>Background: There have been many successful strategies to implement xylose metabolism in Saccharomyces cerevisiae, but no effort has so far enabled xylose utilization at rates comparable to that of glucose (the preferred sugar of this yeast). Many studies have pointed towards the engineered yeast not sensing that xylose is a fermentable carbon source despite growing and fermenting on it, which is paradoxical. We have previously used fluorescent biosensor strains to in vivo monitor the sugar signalome in yeast engineered with xylose reductase and xylitol dehydrogenase (XR/XDH) and have established that S. cerevisiae senses high concentrations of xylose with the same signal as low concentration of glucose, which may explain the poor utilization. Results: In the present study, we evaluated the effects of three deletions (ira2δ, isu1δ and hog1δ) that have recently been shown to display epistatic effects on a xylose isomerase (XI) strain. Through aerobic and anaerobic characterization, we showed that the proposed effects in XI strains were for the most part also applicable in the XR/XDH background. The ira2δisu1δ double deletion led to strains with the highest specific xylose consumption- and ethanol production rates but also the lowest biomass titre. The signalling response revealed that ira2δisu1δ changed the low glucose-signal in the background strain to a simultaneous signalling of high and low glucose, suggesting that engineering of the signalome can improve xylose utilization. Conclusions: The study was able to correlate the previously proposed beneficial effects of ira2δ, isu1δ and hog1δ on S. cerevisiae xylose uptake, with a change in the sugar signalome. This is in line with our previous hypothesis that the key to resolve the xylose paradox lies in the sugar sensing and signalling networks. These results indicate that the future engineering targets for improved xylose utilization should probably be sought not in the metabolic networks, but in the signalling ones.</p>},
  author       = {Osiro, Karen O. and Borgström, Celina and Brink, Daniel P. and Fjölnisdóttir, Birta Líf and Gorwa-Grauslund, Marie F.},
  issn         = {1475-2859},
  language     = {eng},
  number       = {1},
  publisher    = {BioMed Central (BMC)},
  series       = {Microbial Cell Factories},
  title        = {Exploring the xylose paradox in Saccharomyces cerevisiae through in vivo sugar signalomics of targeted deletants},
  url          = {http://dx.doi.org/10.1186/s12934-019-1141-x},
  doi          = {10.1186/s12934-019-1141-x},
  volume       = {18},
  year         = {2019},
}