Establishing a synthetic pathway for high-level production of 3-hydroxypropionic acid in Saccharomyces cerevisiae via β-alanine

Irina Borodina,Kanchana R Kildegaard,Niels B Jensen,Thomas H Blicher,Jérôme Maury,Svetlana Sherstyk,Konstantin Schneider,Pedro Lamosa,Markus J Herrgård,Inger Rosenstand,Fredrik Öberg,Jochen Forster,Jens Nielsen

doi:10.1016/j.ymben.2014.10.003

Abstract

Microbial fermentation of renewable feedstocks into plastic monomers can decrease our fossil dependence and reduce global CO2 emissions. 3-Hydroxypropionic acid (3HP) is a potential chemical building block for sustainable production of superabsorbent polymers and acrylic plastics. With the objective of developing Saccharomyces cerevisiae as an efficient cell factory for high-level production of 3HP, we identified the β-alanine biosynthetic route as the most economically attractive according to the metabolic modeling. We engineered and optimized a synthetic pathway for de novo biosynthesis of β-alanine and its subsequent conversion into 3HP using a novel β-alanine-pyruvate aminotransferase discovered in Bacillus cereus. The final strain produced 3HP at a titer of 13.7±0.3gL−1 with a 0.14±0.0C-molC-mol−1 yield on glucose in 80h in controlled fed-batch fermentation in mineral medium at pH 5, and this work therefore lays the basis for developing a process for biological 3HP production.

Highlights

3-hydroxypropionic acid (3HP) is a platform chemical, which can be converted into acrylic acid, 1,3-propandiol, malonic acid, biodegradable polyesters, and other valuable chemicals
Establishment of 3HP production from glucose or other renewable carbon sources would provide a biosustainable alternative to acrylic acid production from fossil resources
The route where β-alanine is converted into malonic semialdehyde either by the action of β-alanine-pyruvate aminotransferase (BAPAT) or γ-aminobutyrate transaminase (GABT) has been reported in E. coli (Liao et al, 2007) and yeast (Jessen et al, 2012) respectively (Fig. 1a)

Summary

Introduction

3-hydroxypropionic acid (3HP) is a platform chemical, which can be converted into acrylic acid, 1,3-propandiol, malonic acid, biodegradable polyesters, and other valuable chemicals. Borodina et al / Metabolic Engineering 27 (2015) 57–64 unfavorable (Henry et al, 2010) and likely to result in a mixture of lactate and 3HP Another route utilizes malonyl-CoA as precursor, which can be reduced to 3HP via combined action of malonyl-CoA reductase (malonate semialdehyde-forming) and 3-hydroxypropi onate dehydrogenase or 3-hydroxyisobutyrate dehydrogenase. As it was our intention to engineer a high-3HP-producer, it was apparent that the biosynthesis of β-alanine precursor via spermine will most likely not be able to provide high flux and it was preferred to engineer an alternative route for β-alanine biosynthesis from aspartate in yeast. To engineer a de novo route for 3HP production in yeast via the β-alanine pathway it was essential to identify enzymes capable of converting β-alanine into 3HP and to establish a synthetic pathway for efficient synthesis of β-alanine itself.

Objectives

Methods

Results

Conclusion