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Expression of Mitochondrial Cytochrome C Oxidase Chaperone Gene (COX20) Improves Tolerance to Weak Acid and Oxidative Stress during Yeast Fermentation.

Kumar V, Hart AJ, Keerthiraju ER, Waldron PR, Tucker GA, Greetham D - PLoS ONE (2015)

Bottom Line: Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol.Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid.This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress.

View Article: PubMed Central - PubMed

Affiliation: University of Nottingham, School of Biosciences, Sutton Bonington Campus, Loughborough, LE12 5RD, United Kingdom.

ABSTRACT

Introduction: Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol. Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid.

Results: A Δcox20 strain was sensitive to the presence of acetic acid compared with the background strain. Overexpressing COX20 using a tetracycline-regulatable expression vector system in a Δcox20 strain, resulted in tolerance to the presence of acetic acid and tolerance could be ablated with addition of tetracycline. Assays also revealed that overexpression improved tolerance to the presence of hydrogen peroxide-induced oxidative stress.

Conclusion: This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress.

No MeSH data available.


Related in: MedlinePlus

(A) Metabolic activity (redox signal intensity) of Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide (B) Growth rates (OD600) for Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide (C) Viability of Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide measured over 120 mins.Results presented are a representative of triplicate values (Mean +/- SD n = 3).
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pone.0139129.g006: (A) Metabolic activity (redox signal intensity) of Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide (B) Growth rates (OD600) for Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide (C) Viability of Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide measured over 120 mins.Results presented are a representative of triplicate values (Mean +/- SD n = 3).

Mentions: Cytochrome C oxidases have been reported to be involved in cellular response to oxidative stress [17], we thus assessed whether overexpressing COX20 had an effect on tolerance to hydrogen peroxide-induced oxidative stress. Assays revealed that overexpression of COX20 increased metabolic output in the presence of 1 mM hydrogen peroxide when compared with assays using the empty vector containing yeast as a control (Fig 6A). We also observed an improvement in growth and viability in the presence of hydrogen peroxide for cells overexpressing COX20 as compared to the empty vector controls (Fig 6B and 6C).


Expression of Mitochondrial Cytochrome C Oxidase Chaperone Gene (COX20) Improves Tolerance to Weak Acid and Oxidative Stress during Yeast Fermentation.

Kumar V, Hart AJ, Keerthiraju ER, Waldron PR, Tucker GA, Greetham D - PLoS ONE (2015)

(A) Metabolic activity (redox signal intensity) of Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide (B) Growth rates (OD600) for Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide (C) Viability of Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide measured over 120 mins.Results presented are a representative of triplicate values (Mean +/- SD n = 3).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591339&req=5

pone.0139129.g006: (A) Metabolic activity (redox signal intensity) of Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide (B) Growth rates (OD600) for Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide (C) Viability of Δcox20 pCM173 or Δcox20 pCM173(COX20) in the presence of 1 mM hydrogen peroxide measured over 120 mins.Results presented are a representative of triplicate values (Mean +/- SD n = 3).
Mentions: Cytochrome C oxidases have been reported to be involved in cellular response to oxidative stress [17], we thus assessed whether overexpressing COX20 had an effect on tolerance to hydrogen peroxide-induced oxidative stress. Assays revealed that overexpression of COX20 increased metabolic output in the presence of 1 mM hydrogen peroxide when compared with assays using the empty vector containing yeast as a control (Fig 6A). We also observed an improvement in growth and viability in the presence of hydrogen peroxide for cells overexpressing COX20 as compared to the empty vector controls (Fig 6B and 6C).

Bottom Line: Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol.Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid.This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress.

View Article: PubMed Central - PubMed

Affiliation: University of Nottingham, School of Biosciences, Sutton Bonington Campus, Loughborough, LE12 5RD, United Kingdom.

ABSTRACT

Introduction: Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol. Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid.

Results: A Δcox20 strain was sensitive to the presence of acetic acid compared with the background strain. Overexpressing COX20 using a tetracycline-regulatable expression vector system in a Δcox20 strain, resulted in tolerance to the presence of acetic acid and tolerance could be ablated with addition of tetracycline. Assays also revealed that overexpression improved tolerance to the presence of hydrogen peroxide-induced oxidative stress.

Conclusion: This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress.

No MeSH data available.


Related in: MedlinePlus