Multiplexed CRISPR Activation of Cryptic Sugar Metabolism Enables Yarrowia Lipolytica Growth on Cellobiose.

The yeast Yarrowia lipolytica has been widely studied for its ability to synthesize and accumulate intracellular lipids to high levels. Recent studies have identified native genes that enable growth on biomass-derived sugars, but these genes are not sufficiently expressed to facilitate robust metabolism. In this work, a CRISPR-dCas9 activation (CRISPRa) system in Y. lipolytica is developed and is used it to activate native β-glucosidase expression to support growth on cellobiose. A series of different transcriptional activators are compared for their effectiveness in Y. lipolytica, with the synthetic tripartite activator VPR yielding the highest activation. A VPR-dCas9 fusion is then targeted to various locations in a synthetic promoter driving hrGFP expression, and activation is achieved. Subsequently, the CRISPRa system is used to activate transcription of two different native β-glucosidase genes, facilitating enhanced growth on cellobiose as the sole carbon source. This work expands the synthetic biology toolbox for metabolic engineering in Y. lipolytica and demonstrates how the programmability of the CRISPR-Cas9 system can enable facile investigation of transcriptionally silent regions of the genome.