Microbial cell factory optimisation using genome-wide host-pathway interaction screens

Abstract

The ubiquity of genetic interactions in living cells challenges the concept of parts orthogonality, which is a cornerstone of synthetic biology. Parts, such as heterologously expressed genes, draw from shared pools of limited cellular resources and interactions between parts themselves and their host are inevitable. Instead of trying to eliminate or disregard these interactions, we propose to leverage them to promote desirable phenotypes. We recently described CRI-SPA, a method for high-throughput genome-wide gene delivery and screening of host:pathway interactions in Saccharomyces cerevisiae. In this study, we combine this method with biosensor-based high-throughput screening and high-density colony image analysis to identify lead engineering targets for optimising cis-cis-muconic acid (CCM) production in yeast cell factories. Using the biosensor screen, we phenotype >9,700 genotypes for their interaction with the heterologously expressed CCM biosynthesis pathway, including both gene knock-out and overexpression, and identify novel metabolic targets belonging to sulphur assimilation and methionine synthesis, as well as cellular redox homeostasis, positively impacting CCM biosynthesis by up to 280%. Our genome-wide exploration of host pathway interaction opens novel strategies for the metabolic engineering of yeast cell factories.