Genome-scale analyses of butanol tolerance in Saccharomyces cerevisiae reveal an essential role of protein degradation

Genome-scale analyses of butanol tolerance in Saccharomyces cerevisiae reveal an essential role of protein degradation

Gonzalez-Ramos, D.
Van den Broek, M.
Van Maris, A.J.A.
Pronk, J.T.
Daran, J.M.G.

Applied Sciences

BT/Biotechnology

2013-04-03

Background n-Butanol and isobutanol produced from biomass-derived sugars are promising renewable transport fuels and solvents. Saccharomyces cerevisiae has been engineered for butanol production, but its high butanol sensitivity poses an upper limit to product titers that can be reached by further pathway engineering. A better understanding of the molecular basis of butanol stress and tolerance of S. cerevisiae is important for achieving improved tolerance. Results By combining a screening of the haploid S. cerevisiae knock-out library, gene overexpression, and genome analysis of evolutionary engineered n-butanol-tolerant strains, we established that protein degradation plays an essential role in tolerance. Strains deleted in genes involved in the ubiquitin-proteasome system and in vacuolar degradation of damaged proteins showed hypersensitivity to n-butanol. Overexpression of YLR224W, encoding the subunit responsible for the recognition of damaged proteins of an ubiquitin ligase complex, resulted in a strain with a higher n-butanol tolerance. Two independently evolved n-butanol-tolerant strains carried different mutations in both RPN4 and RTG1, which encode transcription factors involved in the expression of proteasome and peroxisomal genes, respectively. Introduction of these mutated alleles in the reference strain increased butanol tolerance, confirming their relevance in the higher tolerance phenotype. The evolved strains, in addition to n-butanol, were also more tolerant to 2-butanol, isobutanol and 1-propanol, indicating a common molecular basis for sensitivity and tolerance to C3 and C4 alcohols. Conclusions This study shows that maintenance of protein integrity plays an essential role in butanol tolerance and demonstrates new promising targets to engineer S. cerevisiae for improved tolerance.

saccharomyces cerevisiae
butanol tolerance
evolutionary engineering
deletion collection screening
whole genome sequencing
proteasome
multivesicular bodies
OA-Fund TU Delft

http://resolver.tudelft.nl/uuid:ae07be2d-7030-409a-8e9e-0b60d829ce14

https://doi.org/10.1186/1754-6834-6-48

BioMed Central

1754-6834

http://www.biotechnologyforbiofuels.com/content/6/1/48

Biotechnology for Biofuels, 6 (1), 2013

Institutional Repository

journal article

© 2013 The Author(s)
Licensee BioMed Central Ltd.