Biology subjects

Troyer, C.

Publications and source records attributed to Troyer, C..

2 recordsLinked to original sources

bioRxiv2023

A native phosphoglycolate salvage pathway of the synthetic autotrophic yeast Komagataella phaffii

Synthetic autotrophs can serve as chassis strains for bioproduction from CO2 as a feedstock to take measures against the climate crisis. Integration of the Calvin-Benson-Bassham (CBB) cycle into the methylotrophic yeast Komagataella phaffii (Pichia pastoris) enabled it to use CO2 as the sole carbon source. The key enzyme in this cycle is ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) catalyzing the carboxylation step. However, this enzyme is error prone to perform an oxygenation reaction leading to the production of toxic 2-phosphoglycolate. Native autotrophs have evolved different recycling pathways for 2-phosphoglycolate. However, for synthetic autotrophs, no information is available for the existence of such pathways. Deletion of CYB2 in the autotrophic K. phaffii strain led to the accumulation of glycolate, an intermediate in phosphoglycolate salvage pathways, suggesting that such a pathway is enabled by native K. phaffii enzymes. 13C tracer analysis with labeled glycolate indicated that the yeast pathway recycling phosphoglycolate is similar to the plant salvage pathway. This orthogonal yeast pathway may serve as a sensor for RuBisCO oxygenation, and as an engineering target to boost autotrophic growth rates in K. phaffii.

microbiology↗

bioRxiv2022

The oxygen tolerant reductive glycine pathway in eukaryotes: a native methanol, formate and CO2 assimilation pathway in the yeast Komagataella phaffii

The current climate change is mainly driven by excessive anthropogenic CO2 emissions. As industrial bioprocesses depend mostly on food competing organic feedstocks or fossil raw materials, we regard CO2 co-assimilation or the use of CO2-derived methanol or formate as carbon source as pathbreaking contribution to the solution of this global problem. The number of industrially relevant microorganisms that can use these two carbon sources is limited, and even less can concurrently co-assimilate CO2. Hence, we searched for alternative native methanol and native formate assimilation pathways which co-assimilate CO2 in the industrially relevant methylotrophic yeast Komagataella phaffii (Pichia pastoris). Using 13C-tracer-based metabolomics techniques and metabolic engineering approaches we discovered and confirmed a natively active pathway that can perform all three assimilations: the oxygen tolerant reductive glycine pathway. This finding paves the way towards metabolic engineering of formate and CO2 utilisation for the production of proteins, biomass or chemicals in yeast.

microbiology↗