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Microb Cell Fact. 2018 Jan 12;17(1):5. doi: 10.1186/s12934-017-0848-9.

Chemical genomic guided engineering of gamma-valerolactone tolerant yeast.

Author information

1
Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, 1552 University Ave, Madison, WI, USA.
2
Lehrstuhl für Chemie Biogener Rohstoffe, Technische Universität München, Schulgasse 16, 94315, Straubing, Germany.
3
School of Biology, Georgia Institute of Technology, Atlanta, GA, USA.
4
University of Wisconsin Biotechnology Center, Madison, WI, USA.
5
Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA.
6
Morgridge Institute for Research, Madison, WI, USA.
7
Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA.
8
Genome Center of Wisconsin, Madison, WI, USA.
9
Department of Computer Science and Engineering, University of Minnesota-Twin Cities, Minneapolis, MN, USA.
10
Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, 1552 University Ave, Madison, WI, USA. jpiotrowski@yumanity.com.
11
Yumanity Therapeutics, 790 Memorial Drive, Suite 2C, Cambridge, MA, 02139, USA. jpiotrowski@yumanity.com.

Abstract

BACKGROUND:

Gamma valerolactone (GVL) treatment of lignocellulosic bomass is a promising technology for degradation of biomass for biofuel production; however, GVL is toxic to fermentative microbes. Using a combination of chemical genomics with the yeast (Saccharomyces cerevisiae) deletion collection to identify sensitive and resistant mutants, and chemical proteomics to monitor protein abundance in the presence of GVL, we sought to understand the mechanism toxicity and resistance to GVL with the goal of engineering a GVL-tolerant, xylose-fermenting yeast.

RESULTS:

Chemical genomic profiling of GVL predicted that this chemical affects membranes and membrane-bound processes. We show that GVL causes rapid, dose-dependent cell permeability, and is synergistic with ethanol. Chemical genomic profiling of GVL revealed that deletion of the functionally related enzymes Pad1p and Fdc1p, which act together to decarboxylate cinnamic acid and its derivatives to vinyl forms, increases yeast tolerance to GVL. Further, overexpression of Pad1p sensitizes cells to GVL toxicity. To improve GVL tolerance, we deleted PAD1 and FDC1 in a xylose-fermenting yeast strain. The modified strain exhibited increased anaerobic growth, sugar utilization, and ethanol production in synthetic hydrolysate with 1.5% GVL, and under other conditions. Chemical proteomic profiling of the engineered strain revealed that enzymes involved in ergosterol biosynthesis were more abundant in the presence of GVL compared to the background strain. The engineered GVL strain contained greater amounts of ergosterol than the background strain.

CONCLUSIONS:

We found that GVL exerts toxicity to yeast by compromising cellular membranes, and that this toxicity is synergistic with ethanol. Deletion of PAD1 and FDC1 conferred GVL resistance to a xylose-fermenting yeast strain by increasing ergosterol accumulation in aerobically grown cells. The GVL-tolerant strain fermented sugars in the presence of GVL levels that were inhibitory to the unmodified strain. This strain represents a xylose fermenting yeast specifically tailored to GVL produced hydrolysates.

KEYWORDS:

Biocatalysts; Biofuel; Chemical genomics; Gamma-valerolactone; Lignocellulosic; Saccharomyces cerevisiae

PMID:
29329531
PMCID:
PMC5767017
DOI:
10.1186/s12934-017-0848-9
[Indexed for MEDLINE]
Free PMC Article

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