A homologous recombination-proficient Yarrowia lipolytica chassis for multiplex genome manipulation.

Abstract

Homologous recombination (HR) greatly facilitates precise genome editing. However, most organisms prefer error-prone non-homologous end joining (NHEJ) for DNA double-strand break (DSB) repair. Here, the NHEJ-proficient Yarrowia lipolytica was transformed into a HR-proficient strain by systematic engineering of recombination machinery, regulating the multiinvasion-induced rearrangement (MIR) process, and expressing cognate single-stranded DNA-annealing protein (SSAP)-single-stranded DNA-binding protein (SSB) pairs. These strategies improved HR efficiency by 38.9, 1.6, and 1.2-fold compared with the NHEJ-deficient strain for multifragment multisite integration, and multi- and single-fragment single-site integration, respectively. Moreover, HR efficiency remained high at 58% even with 50-base pair (bp) homology arms (HAs) and reached 11% for simultaneously integrating two mega-DNA fragments (18.0 kb and 13.5 kb) at two genome sites. This strain also enabled simultaneous editing, repression, and activation of multiple genes, while cellular robustness parameters showed marked increases over the NHEJ-deficient strain. Our work provides a HR-proficient Y. lipolytica chassis allowing efficient and precise genome editing of this increasingly important microbe.