Abstract
Saccharomyces cerevisiae, a generally recognized as safe (GRAS)
microorganism, is regarded as an industrial workhorse for chemical and
recombinant protein synthesis. In the biotechnological industry,
multi-copy gene integration represents an effective strategy to maintain
a high-level production of recombinant proteins-of interest, and to
assemble multi-gene biochemical pathways. In the present study, we first
created a copper-sensitive yeast strain by abolishing the CUP1
gene (encoding metallothionein that binds copper ions). Subsequently, we
harnessed the CUP1 as a selection marker and combined the δ sites
for multi-copy gene integration in S. cerevisiae. With the newly
developed CUP1-tagging platform, multi-copy chromosomal integration of
enhanced green fluorescent protein (eGFP) expression cassette was
achieved, and the engineered strains remained quite stable after
successive rounds of passaging. Taken together, we envision that the
CUP1-tagging system would be a robust and useful method for protein
overproduction and metabolic engineering applications in budding yeast.