Consequences of a telomerase-related fitness defect and chromosome substitution technology in yeast synIX strains.

We describe the complete synthesis, assembly, debugging, and characterization of a synthetic 404,963 bp chromosome, synIX (synthetic chromosome IX ). Combined chromosome construction methods were used to synthesize and integrate its left arm ( synIXL ) into a strain containing previously described synIXR . We identified and resolved a bug affecting expression of EST3 , a crucial gene for telomerase function, producing a synIX strain with near wild-type fitness. To facilitate future synthetic chromosome consolidation and increase flexibility of chromosome transfer between distinct strains, we combined chromoduction, a method to transfer a whole chromosome between two strains, with conditional centromere destabilization to substitute a chromosome of interest for its native counterpart. Both steps of this chromosome substitution method were efficient. We observed that wild-type II tended to co-transfer with synIX and was co-destabilized with wild-type IX , suggesting a potential gene dosage compensation relationship between these chromosomes.
Competing Interests: J.D.B. is a founder and director of CDI Labs, Inc., a founder of and consultant to Neochromosome, Inc, a founder, SAB member of, and consultant to ReOpen Diagnostics, LLC, and serves or served on the scientific advisory board of the following: Logomix, Inc., Sangamo, Inc., Modern Meadow, Inc., Rome Therapeutics, Inc., Sample6, Inc., Tessera Therapeutics, Inc., and the Wyss Institute. J.S.B. is a founder of Neochromosome, Inc., consultant to Opentrons Labworks, Inc., and advisor to Reflexion Pharmaceuticals, Inc.
(© 2023 The Authors.)